J V Vas

F J Cadete

Santos Aires

E Ehret

E Landrivon

M Duchamp

T Epicier

Water Condensation / Evaporation Experiments in ETEM using a Thermoelectric Microcooler

Water Condensation / Evaporation Experiments in ETEM using a Thermoelectric Microcooler J.V. Vas 1,2 , F.J. Cadete Santos Aires 3 , E. Ehret 3 , E. Landrivon 3 , M. Duchamp 1,2 , and T. Epicier 3* 1. MajuLab, International Joint Research Unit UMI 3654, CNRS, Université Côte d'Azur, Sorbonne Université, National University of Singapore, Nanyang Technological University, Singapore, Singapore 2. Laboratory for in-situ and operando Nanoscopy, School of Material Science and Engineering, Nanyang Technological University, Singapore. 3. Université de Lyon, UCBL, IRCELYON, UMR 5256, CNRS, Villeurbanne, France * Corresponding author: thierry.epicier@ircelyon.univ-lyon1.fr Efficient closed-cell specimen holders for Liquid Cell Transmission Electron Microscopy (TEM) has led to many advances over the last two decades but still suffer limitations due to their sealing membranes which hamper comfortable tomography approach, optimized chemical analysis and signal-to-noise ratio. 'Windowless' approaches in a dedicated Environmental TEM can not only overcome these limitations but provide opportunities to study water (liquid) condensation-evaporation experiments as required for example to study the water uptake of aerosols in the context of climate and atmospheric chemistry [START_REF] Wise | Phase Transitions of Single Salt Particles Studied Using a Transmission Electron Microscope with an Environmental Cell[END_REF]. We present here a development and operationalization of such a windowless Wet ETEM method using a Peltier based MEMS chip compatible with a DENSsolutions Wildfire holder. The environmental conditions for the evaporation and condensation cycles require a pressure of 6-15 mbar and a temperature within a 0-11oC typical range. As for Environmental Scanning EM (ESEM) [START_REF] Bogner | Wet STEM: A new development in environmental SEM for imaging nano-objects included in a liquid phase[END_REF], these conditions can be achieved using a FEI-Titan ETEM instrument installed at CLYM Lyon, where a gas pressure of up to about 20 mbar can be maintained around a cooled specimen in the pole pieces gap. Adequate temperatures were obtained by placing at the tip of the Wildfire holder a thermoelectric cooler which can produce a temperature difference of ~40 K between the hot and the cold junctions. A 'micro' Peltier stage with adequate dimensions for being safely introduced in the ETEM was then connected to a custom printed circuit board (PCB) compatible with the DENSsolutions holder. The sample is deposited on a classical TEM carbon grid mounted in direct contact with the cold side of the Peltier device insuring its efficient cooling. Figure 1 shows the tip of the Wildfire holder when equipped with the Peltier system. Initial experiments have been conducted on NaCl crystals used as model aerosols [START_REF] Wise | Phase Transitions of Single Salt Particles Studied Using a Transmission Electron Microscope with an Environmental Cell[END_REF]. Owing to the fast cooling when a current is applied to the Peltier, a very efficient and easily controlled condensation was observed with a vapor pressure typically around 7 mbar in the column as illustrated by figure 2. These preliminary results will be discussed in comparison to similar experiments conducted with a classical cryo-holder (Elsa model from Gatan) cooled down by a liquid nitrogen reservoir as previously performed [START_REF] Wise | Phase Transitions of Single Salt Particles Studied Using a Transmission Electron Microscope with an Environmental Cell[END_REF][START_REF] Levin | An Open-Cell Environmental Transmission Electron Microscopy Technique for In Situ Characterization of Samples in Aqueous Liquid Solutions[END_REF]. As a first statement it appears that a much better and faster stability, resulting in a much better knowledge of the exact relative humidity (RH), is obtained with the proposed solution. Improvements of the setup are still possible. These results offer new perspectives for the study of the deliquescence or efflorescence of aerosols through condensation and evaporation cycles which can then be easily performed and reproduced [START_REF]This work is support by the French National Research Agency under the WATEM program[END_REF].

Figure 1 .

 1 Figure 1. Montage of the micro Peltier system, including a Cu support, a PCB (a) and a fixing cap maintaining the TEM grid (b) on the tip of a Wildfire heating holder from DENSsolutions.

Figure 2 .

 2 Figure 2. sequence of low mag bright field images (Gatan OneView camera) showing the fast condensation of water on a TEM carbon grid with NaCl and some other crystals (Titan ETEM, 300 kV, 7 mbar of water vapor; the temperature is estimated to about 6°C). The Peltier stage is powered at 0.5 s (image slightly out of focus); the droplet appears within less than one second from the grid corner (dark area on the left); the final image shows the extension of the water drop just before shutting the current down.


Daniel Chicouène
email: daniel.chicouene@orange.fr

Inventory and mechanisms of cultural control practices for weed management, a review

Keywords:

An inventory of cultural control practices is undertaken by considering each practice for its biological selectivity with respect to weeds. Descriptions of cultural practices in the literature are often brief. Some recent syntheses neglect knowledge from older publications. Disagreement concerning the delimitation of these practices is common. Clarification of the knowledge base concerning the cultural management of field flora is required for "sustainable agriculture". The selectivity most often mentioned for each practice is limited to a few examples of taxa in a geographically limited area and is rarely considered in the light of general mechanisms of action on biological cycles. The controversial distinction made by many authors between preventive and curative methods is unnecessary. Each practice listed is presented with its biological target. On the scale of a single cultural cycle, thirty practices are compared. Each target tends to have a specific biological descriptor. Most of the practice target pairs have the disadvantage of having an extreme state opposed to that of the target. Crop rotations are described as successions between non-competitive crops or practices that encourage certain weeds on the one hand and cleaning crops or practices on the other. The latter mainly target diaspores that have a lifespan inferior to the planned cleaning duration. The allelopathic after-effects show three mechanisms. In temperate climates, rotations may be complex with respect to the diversity of crop and weed phenologies. Combinations of cultural interventions must take into account the mechanisms involved, particularly because some results could cancel each other out.

Introduction

"Cultural control" means the adjustment or the simple organization of cultural practices in order to reduce the effects of enemies. For several reasons, effective cultural methods are usually required for sustainable agriculture (Singh et al. 2009;[START_REF] Jabran | Non chemical weed control[END_REF]. In the context of integrated or sustainable crop weed management and, more globally, field flora management; it is important to identify the possible effects of many cultural practices (Upadhyaya and Blackshaw, Pawar (2009), Walia (2010) or [START_REF] Subramanian | All about weed control[END_REF]. Comparisons with the other authors would be more difficult. Amongst others, the F.A. O. synthesis (1986) provides three categories "cultural control, cultural practices, cropping patterns", which are not distinguished from one another, due to the lack of sufficient definition. The case of crop rotations taken from the textbooks in Supplementary file is set out in Table 1, which shows that they are listed under either strategies or control methods. Most of the references classify these practices under the heading of strategies, but according to two opposing trends: these range from eradication, extermination, destruction or control (for the first nine lines) to prevention (case for the last two lines and the article by [START_REF] Anderson | Managing weeds with a dualistic approach of prevention and control[END_REF]. Where cultural control is defined (i.e. in thirteen of the 25 works in table 1, in lines 7 to 16), their classification coincides five times with strategy headings and is related to "control". Muenscher (1936) 5 "control" - [START_REF] Klingman | .) 297; competition (fast-growing grains, fertility... 298. Small-seeded legumes (alfalfa[END_REF], [START_REF] Ross | Applied weed science[END_REF] 6 "holding, "control" - [START_REF] Bolley | Weeds and methods of eradication: weed control by means of chemical sprays[END_REF] 7 "control" and eradication" "cultural" Ahlgren & al. (1951) The application of the notion of strategy to cultural practices, particularly to rotations, therefore varies according to the authors, the interpretation of contradictions should be considered by clearly explaining the possible concepts of the control strategies. Depending on the textbooks or articles, cultural methods are perceived using broader or narrower time and space scales: they range through the choice of seed batches, the management of a crop (for example advancing or delaying planting date), to rotations. However, the latter is not integrated into cultural methods by Gwynne and Murray (1982), Pawar (2009) or p.p. [START_REF] Naylor | Weed management handbook[END_REF]. These different delimitations of cultural practices are not necessarily justified, or the corresponding practices are not all classified as such. The practices that they encompass are variously considered to be preventive or curative strategies, or are set out without reference to strategy. For a proper understanding of the notion of prevention, the level of reasoning should always be indicated (Chicouène, 2000b). The main strategies applied at the field spatial scale are compared in table 2: the authors in supplementary file could be located in different cells of the two columns compared. For example, the expression

Chicouène.

493 " [...] preventive and curative measures" in the title of the article by [START_REF] Colbach | Reduced herbicide use does not increase crop yield loss if it is compensated by alternative preventive and curative measures[END_REF] does not give any information as to its content. Additionally, these notions and their levels of reasoning are not necessarily specific to cultural methods. These nuances are at best meaningful in a spatiotemporal context explicit to each use. Therefore, in order to fully understand cultural methods, other complementary criteria of these notions should be considered. Due to this confusion of possible reasoning, it is best to try and consider the list of cultural practices without taking any notice of this classification into ill-defined strategies.

The reality of cultural control approaches

Approaches to cultural methods, therefore, prove to be quite rare in the literature. The possibilities that they offer would merit a simple inventory and an overall assessment of the knowledge base. With this in mind, and with the requirement of classifying cultural practices and their literature (books and articles), several descriptors are available and relevant, particularly the types of spectra of the activity or the types of selectivity [START_REF] Chicouène | Typologie des sélectivités des principales méthodes de lutte contre les mauvaises herbes[END_REF], which provide important guidelines for developing control methods. This essential theme of biological cycles is logically considered with respect to scales of timely effectiveness required as a priority for a field.

To achieve this, it is useful to distinguish two main groups of cultural practices: on the one hand, those that relate to cultural successions in general (discussed in [START_REF] Chicouène | Le raisonnement des successions culturales : I. Caractérisation préalable des populations d'ennemis[END_REF] concerning the issues of stocks of diaspores in the soil and Chicouène 2007a concerning phenology), which encompass the first three lines (especially cell A.3) in table 2, on the other hand, the remainder, i.e. reasoning based on a single cultural cycle (discussed in [START_REF] Chicouène | Cibles biologiques de 26 méthodes culturales de lutte contre les mauvaises herbes dans le cycle d'une culture[END_REF], corresponding to the entire contents of the last line in table 2, perhaps also to cell B.3. The aim here is to regroup the cultural practices and their approaches encountered in the literature. The comparative approach is based precisely upon their biological targets of weeds and equally on their limits. Only crops subject to rotations are considered, whatever the climatic zone. The main inputs are, therefore by order of complexity of approach: a single cultural cycle, followed by cultural successions. A general discussion is then proposed.

Reasoning on a single cultural cycle

This approach is focused on the organization or the operating cycle of a single crop, or on one year for a meadow in a seasonal climate. It consists of exploiting the characteristics of a cultural cycle, while considering only the future harvest, with a given weediness of the field before applying cultural methods. Generally, the main aim is to reduce the potentially strong harmful effect of weeds present at the moment the decision is taken, whether these weeds are in a resting state or actively growing.

Two scales of understanding are distinguished:

-The field with its stock of weeds in or on the soil, -Seed batch production management, particularly as concerns the mimicking weeds of a crop cycle.

The cultural practices listed

How the inventory is carried out

The practices in the supplementary file and in some articles are grouped in table 3 (with six practices), 4 (with thirteen practices) and 5 (with ten practices corresponding to five descriptors which each have two extreme statuses): they originate from [START_REF] Chicouène | Cibles biologiques de 26 méthodes culturales de lutte contre les mauvaises herbes dans le cycle d'une culture[END_REF] except that the examples of taxa, observed in temperate oceanic climates, have been removed and that certain practices have been added (denoted by numbers "bis"). A few cultural practices that use high temperatures are not included in the table: composting (Shaw, 1892: 5, etc. in supplementary file), controlled burning (Muenscher, 1936: 60, etc. in supplementary file), soil solarisation [START_REF] Radosevich | Weed ecology, implications for vegetation management[END_REF][START_REF] Naylor | Weed management handbook[END_REF]Gupta, 2007;Pawar, 2009;Walia, 2010;[START_REF] Chaudary | Weed management, principles and practices[END_REF]) and fertilizer types.

Concerning crop management, the literature contains 2 different logics:

-The logic least frequently encountered consists of aiming for the chosen crop's phytotechnical optimum, for example, "planting at optimum date" (Smith et al., 1995: 411;[START_REF] Lee | Weed control under conservation agriculture in dryland smallholder farming systems of southern Africa. A review[END_REF][START_REF] Jabran | Non chemical weed control[END_REF]. The presupposition probable in this case is that the crop benefits from the best compromise conditions to resist a maximum of possible weeds.

Table 3. Cultural practices with simple actions, without disadvantages from the point of view of weed science (Chicouène 2016 modified).

Practices, cultural descriptor

advantages, targets possible disadvantages, hypotheses for possible limits 1) thorough sorting of seed batches: (Muenscher 1936: 18, 54;Ahlgren & al. 1951: 16, 126, 159;Zimdahl 1993: 99, etc. in supplementary file; Chicoue ne 2016) ,

mimicking weeds, -new species (or new genes, particularly those for herbicide resistance) in the field* spread by seed batches -1bis) choice of a cultivar that facilitates sorting cultivars of Fagopyrum esculentum with large seeds in order to exclude the seeds of Datura stramonium more easily (Chicoue ne 2010)

(may select another mimicking weed)

2) cleaning of tillage or harvest tools, [START_REF] Brenchley | Weeds of farm land[END_REF]: 44, Muenscher 1936: 55, Robbins & al. 1942: 63, Fryer & Matsunaka 1977: 23, Zimdahl 1993: 74-6, Smith & al. 1995: 40, etc. in supplementary file, Chicoue ne 2016, Evers & Bastiaans 2016) , reduce the introduction of new taxa or genes in a field (or reintroduction when they have been eradicated)*

3) spatial arrangement of planting (Ahlgren & al. 1951: 7, Fryer & Matsunaka 1977: 11, Altieri & al. 1988: 206, 221-2, Smith & al. 1995: 416, Walia (2010: 91, Drew & al. 2009, Boyer & al., 2016, against Lolium rigidum in cereals, Chicoue ne 2016) regular dispersal of the crop in order to optimize smothering of seedlings or late emergence of heliophilous species 4) crop shorter than the weeds (at least some stages) (Chicoue ne 2016)

opportunity for visual identification of tall weeds at low density for localized destruction -application of a height selective method (contact with an electric boom or a boom imbibed with herbicide, lopping machine) if high density-frequency (fallen or dwarf individuals (due to vegetation density, deficiencies, biological regulation) are not necessarily taller than the crop) 5) elimination of chaff (Boyer & al., 2016, against Lolium rigidum in cereals, Tideman & al. 2016 for Avena fatua, Chicoue ne 2016, [START_REF] Lee | Weed control under conservation agriculture in dryland smallholder farming systems of southern Africa. A review[END_REF] reduces input to the soil of some mimicking weeds or crop residues (reduces food for seed-consuming regulators and reduces ground cover by crop residues) 5bis) mixted cropping (King 1966: 418-9, Altieri & al. 1988: 205, 309;[START_REF] Zimdahl | Inventory and mechanisms of cultural control practices for weed management, a review[END_REF]: 182-3, Smith & al. 1995 -The logic developed here (for example in tables 3 to 5), which is the most frequent, is to move away from the chosen crop's phytotechnical optimum, or even to choose a crop or a method of management in order to best avoid some particularly noxious weeds that are present, taking into account the known biology of crop and weed. Therefore, "cultural controls [...] usually only require modifications to normal production practices " (Pawar, 2009). For example, sowing is earlier as opposed to later [START_REF] Naylor | Weed management handbook[END_REF]. The aim here is to strongly reduce a harmful effect by choice or adjustment of cultural practices: the risk is that yield may sometimes be slightly degraded or the operating costs changed by technical issues (for example, crop fall due to dense sowing, dirt and humidity in the harvested crop in the event of an early harvest), additional operations (e.g. sorting)

or reduced working speed (for example due to a very low cut). Certain cultural choices sometimes use other methods, not directly cultural (for example, selective mechanical intervention becomes possible due to wide spacing of the crop rows studied by [START_REF] Drew | Weed suppression ability of three winter wheat varieties at different row spacing under organic farming conditions[END_REF] for wheat otherwise considered as dirty crops, or a crop where a roller pass is possible just after its emergence in order to break fragile stems such as those of Datura stramonium or Xanthium strumarium).

Technical classification of the list of practices.

The descriptors used to characterize the relationships with weed cycle's concern different aspects or steps of the cultural cycle; these are shown in tables 3 to 5:

-choice of the crops in the field: the "traditional" type of crop with respect to selective [START_REF] Brenchley | Weeds of farm land[END_REF][START_REF] Robbins | ) 124; water (irrigated, drainage) 127; soil fertility (nitrogenous fertilizers) 127; liming 128; date and rate of seeding[END_REF], pH in Altieri et al. 1988), [START_REF] Kone | Basal Fertilizer Effects on Weed Occurrence and Rice Yield in Acid Upland Soil of West Africa at Bénin[END_REF], fertilization (Fryer et al. 1977[START_REF] Klingman | .) 297; competition (fast-growing grains, fertility... 298. Small-seeded legumes (alfalfa[END_REF][START_REF] Altieri | Weed management in agroecosystems: ecological approaches[END_REF][START_REF] Lee | Weed control under conservation agriculture in dryland smallholder farming systems of southern Africa. A review[END_REF], drainage and irrigation-flooding (Robbins et al. 1942, etc. in supplementary file)

acidophilous and low fertility weeds by soil conditioners and fertilization , -nitrogenous fertilization against leguminous weeds (Robbins: 127), -hygrophilous species by draining (Muenscher 1936;[START_REF] Altieri | Weed management in agroecosystems: ecological approaches[END_REF]) Singh & al.: 865, nitrogenous fertilization (Long: 42, Altieri & al. 1988: 219, Jabran & Chauhan 2018) and potassium fertilization (Altieri & al. 1988: 219) [START_REF] Robbins | ) 124; water (irrigated, drainage) 127; soil fertility (nitrogenous fertilizers) 127; liming 128; date and rate of seeding[END_REF], Ahlgren & al. 1951[START_REF] Muzik | Weed biology and control[END_REF][START_REF] Altieri | Weed management in agroecosystems: ecological approaches[END_REF][START_REF] Zimdahl | Inventory and mechanisms of cultural control practices for weed management, a review[END_REF], Smith & al. 1995: 447, Upadhyaya & al. 2007

The biological targets.

The types of targets for each practice are assessed with reference to a cultural optimum without weeds: they are shown in the second column of tables 3 to 5.

General characteristics of the targets.

Several criteria are used to characterize the targets. In the literature, the most easily encountered criterion is their taxonomic spectrum. The latter corresponds to a few taxa with very specific biological characteristics such as a restricted period of emergence, at least for production of vigorous individuals, to the entire heliophilous flora, i.e. except for sciophilous weeds or even climbing weeds. The biological selectivity proposed in tables 3 to 5 has a general overall value. Its descriptors are quantitative when a time difference to the phytotechnical optimum can be expressed as a number of days or as dimensional units (especially absolute or relative heights). The level of effectiveness expressed as a proportion of repression could possibly be proportional to the intensity of the practice carried out or to the divergence from the phytotechnical optimum. The experimental data on these aspects and their relationships remain limited (for example between sowing density and crop yield in a field more or less densely infested with heliophilous and nonclimbing weeds). Most of the practices retained, i.e. 25 out of 30, have a specific biological target. In most cases, the latter is already mentioned in the bibliography. These targets are independent of one another except when mimicking weeds are particularly concerned: they may then be Chicouène.

499

redundant and/or complementary (subject described later). The targets are described by phenology, ecology (especially of emergence and seedlings) and morphology. Most are considered primarily within a single cultural cycle. Some that concern the soil will act during several successive years.

Table 5. Cultural practices with extreme state-effect pairs (reversed from the point of view of weed science).

Cultural descriptor, practices

Advantages, targets Disadvantages, limits 1) date of sowing in seasonal climates: (Ahlgren & al. 1951, etc. in crop distribution increasing its smothering power [START_REF] Chaudary | Weed management, principles and practices[END_REF]: 96, Walia, 2010[START_REF] Borger | Eleven years of integrated weed management: long term impacts of row spacing and harvest weed seed destruction on Lolium rigidum control[END_REF] prevents any hoeing 5b) increased for durtying crops allows hoeing or localized treatment -reduces the smothering power of young crops, -increase emergence of heliophilous weeds between the rows 500

Relationships between targets and harmfulness.

All types of harmfulness as listed by Chicouène (2010, in major temperate crops) may be anticipated. They are not restricted to yield, sometimes the only type considered in publications.

They concern the other aspects, which are, on the one hand, technical problems (e.g. in order to avoid late vegetative invasion interfering with the harvesting operation, an early harvest is considered), on the other hand, toxicity, particularly sorting of food harvests. In the latter situation, due to the low thresholds of harmfulness, high levels of effectiveness are sought. For example, a buckwheat cultivar with large seeds renders the elimination of Datura stramonium seeds easier in harvests from infested fields. Careful sorting of batches earmarked for consumption or sowing for some Lolium such as Lolium temulentum, a mimicking weed in wheat, is a subject described later.

The reverse effects of biological targets.

Types of biological spectra concerned

Weeds are compared with one another here by considering their biological diversity. The nontarget part of a practice has two levels. From a general point of view, "cultural controls may be effective for one pest but may be ineffective against a closely related species" (Pawar, 2009: 161).

We must also distinguish the case where the practices encourage enemies: the phenomenon is encountered for most of the practices considered by [START_REF] Chicouène | Cibles biologiques de 26 méthodes culturales de lutte contre les mauvaises herbes dans le cycle d'une culture[END_REF]. In the bibliography, this subject is considered far less often than the targets because it requires the characterization of several taxa with respect to each other. Specifically, in the last column of tables 3 to 5, the limits (table 3) and the disadvantages or reverse effects (tables 4 and 5, i.e. respectively thirteen and ten cases) corresponding to each practice-target pair are explained. Thus, case 5.1 of the planting date chosen to be unfavorable for a specific type of emergence calendar is at the same time the most optimal for taxa responding in a contrary manner to this date. The dilemma becomes crucial in a field when at least one weed requires one measure and at the same time, another weed justifies the opposing measure or risks selecting this latter taxon. The characteristics of a non-target flora opposed to the target of the practice considered should be rationalized at the scale of an area geographically greater than that dominating the single field at a given moment: species known to be major weeds in nearby fields may be selected so long as they are present.

Interpretation of reverse effects.

The most quantitative targets see their reverse effects described by the same descriptor but in the opposite direction: proportionality can be considered between the two directions of description. In table 5 itself, the targets and their reverse effects tend to be inversed in pairs by

Chicouène.

501

descriptors with two opposite extreme states. This aspect already noted by [START_REF] Chicouène | Cibles biologiques de 26 méthodes culturales de lutte contre les mauvaises herbes dans le cycle d'une culture[END_REF] gathers together more cases here.

Table 2 (ligne 1) describes the soil physico-chemical properties. Modifications of these may have an effect on several successive cycles or on several cultural successions in the field. Liming in acid soils encourages some taxa at the expense of others (e.g. Koné et al,. ., 2014, on rice in Benin). The ecological interpretation would be that the most neutrophilic weeds replace the most acidophilous weeds by several hypotheses of mechanisms (competition or interference, or the neutrophils weeds colonize after the acidophilous weeds are eliminated due to the toxicity of calcium for the latter, or to higher levels of parasitism, or sometimes by a choice of crops that are more competitive in these conditions). Over a cultural cycle, numerous mechanisms, therefore, seem to come into play and the interpretation hypotheses are proposed with varying precision in the last column of the three comparison tables. In the same way, as for targets, the avenues of plant architecture and of physiology are equally important but via their opposite status. The choices between the different cultural practices depend on the dirtying of the field or the crop, by considering the various types of parameters present and their integration into the production cycles. Consideration should also be taken of the possible consequences of these decisions over the following years.

Case of mimicking weed taxa in seed batches.

Linked to the subject of cultural successions, there are numerous cultural practices concerned in tables 3 to 5 that justify placing mimicking weeds in the part concerning a single cultural cycle.

Issue of the harmfulness of mimicking weeds.

Concern for the purity or sorting of agricultural seeds appears regularly in the books in the supplementary file, especially the oldest ones (in the 11 published before 1970, then in 21 out of the 31 published later). The principle consists mainly of taking account of taxa new to a field or taxa reintroduced after their eradication (Chicouène, 2000b). This subject particularly concerns mimicking weeds of crop sowing and harvesting cycles. They are taxa "closely associated with a particular crop" (Barett, 1983). Some taxa are close relations of the crops, of which they may be ancestors: Altieri & Liebman (1988: 61 & 221) mention several species in this case. The subject is also important when the diaspores concerned are toxic as are some species of Lolium in several small-grain cereals and in linseed. The case of control of Lychnis githago is discussed by [START_REF] Brenchley | Weeds of farm land[END_REF], who recommends sorting just before the harvest. However, the stages of the cycle where cultural control is feasible are numerous. These sorts of the plant are specifically targeted six times in tables 3 to 5 (lines 3.1, 3.1bis, 3.2, 3.5, 4.12, 5.4b). Comparison of these interventions between 502 each other shows effects that are either complementary (e.g. harvest and sorting in 3.1 and 5.4b), or redundant (e.g. cleaning tools in 3.2 and prevention of maturation in 4.12).

The cycle of crop mimicking weeds and control practices.

In the typical state, stocks of diaspores of mimicking weeds are logically limited to contaminated agricultural seed batches ("seed mimicry" in McElroy, 2014), passing every year from one field to another according to crop rotations that include the incriminated crop: in other words, their effective stock of diaspores in the field (on or in the soil) is, therefore, zero or close to zero. The contamination of an initially exempt cultivar batch can theoretically occur via several possibilities that determine the effective interventions (Figure 1).

503

-or via a very low but non-zero stock in the soil: when the harvester cutting height is not low enough, a few ephemeral diaspores that do not enter the harvester may remain on the soil (see table 5, line 4b).

Assuming abiotic potential greater than that of the mimicked crop, depending on the level of investment in these practices of cultural control, the infestation rate of the batch that has just been contaminated will either show slower progress compared to complete absence of control, or will be stabilized, reduced or eliminated. The subject of mimicking weeds is linked to cultural successions:

the reasoning is an anticipation of the seed batch for the following year rather than the spatial scale of the same field in which a crop rotation takes place. The classification as a strict mimicking weed is valid in the context of a cropping system. Depending on the proportion of the stock, on the one hand in the seed batches, on the other hand in the soil (low or ephemeral), a quantitative classification of mixed taxa (i.e. partly mimicking weeds) can be considered.

For mimicking weeds, the biological targets do not have the issue of opposite targets.

Cultural successions

The principle is to exploit crop successions or even different ways of managing a crop, including intercrops, with the aim of limiting the infestations of the following crops. In the wider sense, this notion may encompass any practice that impacts weed cycles, whatever the control methods: in this context, these practices and their organization are intended to limit the effective stock of certain diaspores likely to emerge in a future crop.

General remarks concerning the historical descriptors of practices

The word crop "rotations" is quoted in 37 out of 42 books in the supplementary file. The more general expression of successions is rare (i.e. [START_REF] Hakansson | Weeds and weed management on arable land : an ecological approach[END_REF]. In that of [START_REF] Saraswat | Weed management[END_REF] or in the article by [START_REF] Andrade | Weed communities respond to changes in the diversity of crop sequence composition and double cropping[END_REF], the notion is labeled as "crop sequence". Although the subject is frequent, in nearly all the works the corresponding text consists of one page or less. Singh et al. ( 2006) is an exception, especially while dealing with two specific cases of geographical areas ("semiarid" and "Canadian Prairies", respectively with 21 and 31 pages) and that of herbicide resistance (in less than a page). The implicit criteria of alternation mentioned in the list of books quoted above are summarized and classified hierarchically in table 6 into six superior groups and 17 inferior groups. The precision of the definition of these groups is variable:

-The weakest conceptual formulation of descriptors is the simple mention of different cultivated taxa. This is the first group, with 16 references on species, one on families, one between Monocotyledonae and Dicotyledonae. species of crops: [START_REF] Bolley | Weeds and methods of eradication: weed control by means of chemical sprays[END_REF][START_REF] Long | Common weeds of the farm & garden[END_REF][START_REF] Pammel | Weeds of the farm and garden[END_REF][START_REF] Craft | Modern weed control[END_REF][START_REF] Klingman | .) 297; competition (fast-growing grains, fertility... 298. Small-seeded legumes (alfalfa[END_REF][START_REF] Zimdahl | Inventory and mechanisms of cultural control practices for weed management, a review[END_REF][START_REF] Aldrich | Competitiveness, crop-weed 27-28. Production practices affect weeds: weed introduction[END_REF], Buhler & al. 1997[START_REF] Radosevich | Weed ecology, implications for vegetation management[END_REF][START_REF] Monaco | Weed science, principles and practices[END_REF][START_REF] Naylor | Weed management handbook[END_REF][START_REF] Hakansson | Weeds and weed management on arable land : an ecological approach[END_REF][START_REF] Saraswat | Weed management[END_REF][START_REF] Singh | Handbook of sustainable weed management[END_REF] [START_REF] Klingman | .) 297; competition (fast-growing grains, fertility... 298. Small-seeded legumes (alfalfa[END_REF][START_REF] Ross | Applied weed science[END_REF][START_REF]Instructor's manual for weed management[END_REF][START_REF] Zimdahl | Inventory and mechanisms of cultural control practices for weed management, a review[END_REF], Smith & al. 1995, Buhler & al. 1997[START_REF] Monaco | Weed science, principles and practices[END_REF][START_REF] Naylor | Weed management handbook[END_REF][START_REF] Singh | Handbook of sustainable weed management[END_REF] -The cultural aspect includes several traditional descriptors of practices. Functions that are a priori cleaning in the succession are described in lines 2.1, 2.2 and 2.b, without mention of either taxonomic or biological targets. To compare the effects of rotations on weeds, [START_REF] Singh | Handbook of sustainable weed management[END_REF] consider additions to the density of all species combined. The notion of "break crops" (Gupta, 2007) implies targets of weeds mainly known as plant parasites (e.g. Orobanche in [START_REF] Labrada | Weed management for developing countries[END_REF]. A quality or capacity for competition or groundcover is mentioned in lines 2.3 to 2.5.

-Line 2.b serves as the transition with the use of other methods, specifically mechanical practices (line 3.1 with 11 quotes). Chemical practices are also quoted in the works from recent decades (line 3.2 with 14 references) either for their alternation with other methods or between different chemical practices.

Inventory and mechanisms of cultural control practices …

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-Temporal criteria include general ideas (lines 4.1 to 4.3) that encompass cycle length in the form of annual as opposed to perennial crops, or calendars or general phenology of the crop (number of days for some annual crops). In addition, in temperate climates, there are alternations of dates or seasons for planting and/or harvesting, with 11 references in line 4.5.

-The edaphic criteria (lines 5.1 to 5.3) during a rotation mainly concern strong fertilization for a crop that demands a soil rich in nutrients, followed by less and less demanding crops.

-Lines 6.1 and 6.2 correspond to rarely quoted criteria, which are more or less precise.

Biological mechanisms involved

The aspects of diaspore demography linked to the rotation are first presented in a general manner, and then focused on cleaning.

Shared principles for the organization of a cultural succession.

Concerns about the biological mechanisms involved when using rotations have developed progressively since the start of the 20th century. The notion of "cleaning crop" as mentioned by [START_REF] Brenchley | Weeds of farm land[END_REF] remains a vague assessment. In weed control or agronomy textbooks, description of the succession is generally limited to examples of crops or types of crops, without strict recommendations concerning the choice of sequence. Alternation should logically be between dirty crops and cleaning crops, or even leaving the land fallow (i.e. [START_REF] Singh | Handbook of sustainable weed management[END_REF]. The latter categories are presumed to precede the crop with the highest added value for the farmer, which would also be more sensitive to a given level of dirtiness. This concept of more or less regular empirical successions leads us to consider the underlying biological mechanisms. Several biological phenomena are already possible in the effects of a preceding crop. The case of the results of a rye crop as the main crop or as ground cover, especially when considered as mulch, is widely documented (see [START_REF] Singh | Handbook of sustainable weed management[END_REF]. The effect of harvest residues on the development of weeds in the following crop is on the one hand mechanical by ground cover, on the other hand, chemical by allelopathy. It concerns the stock that may be active in the crop concerned. In addition, a direct demographic role depends on the non-renewed stock of diaspores. The essential biological descriptors relating to cultural successions are compared by [START_REF] Chicouène | Le raisonnement des successions culturales : I. Caractérisation préalable des populations d'ennemis[END_REF]. They are reviewed schematically in Figure 2. In a balanced rotation, in terms of taxonomic selectivity, the taxa that multiply in certain crops should theoretically be the same as those that are reduced by other crops; otherwise, after several cycles of the rotation, there would be important changes in the flora. However, in an ordinary succession such as that shown in figure 2, the question arises as to whether the multiplied and cleaned stocks should be considered as identical.

Organization of cleaning the stock of diaspores

Generally, cleaning implies reproduction inferior to losses during the cultural cycle, the ideal being the absence of reproduction. The time limit for the exhaustion of a stock of diaspores implies that the stock is not renewed during a time span that exceeds its life span. Prevention of multiplication (2nd line in table 2) at least avoids any increase of the stock. This strategy (Chicouène, 2000b) is of interest in two types of situation:

-For long-lived diaspores where the population is still very low in the field, -For diaspores with lifespans shorter than the series of cleaning crops and intercrops, whatever the population level.

The usual mechanisms for the exhaustion of stocks are assumed to be of three types:

-Biological regulation (diseases and predation, the latter being considered particularly in the absence of soil cultivation by several publications), 508 -Death of dormant diaspores or diaspores that have germinated but failed to emerge, -Emergence, which, depending on the taxa, is either encouraged or inhibited by recent cultivation of the soil [START_REF] Chancellor | Emergence of weed seedlings in the field and the effects of different frequencies of cultivation[END_REF][START_REF] Chicouène | Typologie des périodes de levée des mauvaises herbes à partir d'organes végétatifs sous climat tempéré océanique[END_REF]. These 3 mechanisms active during the cultural cycle and in intercrops.

As cleaning durations depend on the persistence of the diaspores, various strategies acting on the stocks are possible. They are summarized by [START_REF] Buhler | Expanding the context of weed management[END_REF]. In the context of a succession, the survival curve of the diaspores determines the number of years required for cleaning. The absence of multiplication, therefore, concerns different scales of the time period:

-When the stock survives for less than a year or one cultural cycle, a biennial rotation is enough. Chicouène (2007a) lists the possibilities for destroying or preventing the renewal of vegetative short-lived diaspores when they are seasonal.

-Two years without reproduction is long enough to get rid of diaspores that survive for one year, several species of this type are studied by [START_REF] Froud-Williams | The effects of seed burial and soil disturbance on emergence and survival of arable weeds in relation to minimal cultivation[END_REF].

-Three years are necessary for diaspores that survive exceptionally for two years (this is sometimes the case for Arrhenatherum bulbosum corms according to [START_REF] Clerch | La biologie de l'Avoine à chapelet Arrhenatherum elatius[END_REF].

-If diaspore persistence lasts for many years, it is inconceivable to have a sufficiently long cleaning duration in the context of simple cultural succession.

Cleaning by putting the land into the meadow, managed either by mowing or grazing, is mentioned several times. [START_REF] Brenchley | Weeds of farm land[END_REF] indicates some species that grow in both perennial meadows and annual crops. For weeds specific to annual crops, the survival of diaspores with life spans exceeding the time the land is kept under meadow is also mentioned by [START_REF] Brenchley | Weeds of farm land[END_REF] and some limited comparative data are quoted by [START_REF] Altieri | Weed management in agroecosystems: ecological approaches[END_REF]. So for Avena fatua, the caryopses survive in a three-year meadow but their stock is exhausted by three years of spring barley without reproduction.

Persistence of cleaning

The objective is to be able to plant the maximum number of crops that are potentially multiplying for major weeds, without this multiplication taking place due to the diaspores having been eradicated during a preceding succession: cleaning for these diaspores, therefore, becomes unnecessary. This strategy is put into perspective by Gupta (2007) who considers it to be an "expensive adventure" for an "area". In fact, it depends on the efforts that must be implemented for the complete cleaning of a challenging weed species in a field. This persistence of a valuable Chicouène.

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cleaning effect after eradication of an effective stock in the field obviously only lasts so long as recontamination does not occur. Reintroduction occurs in the same way as for any new species, by natural means from neighboring fields or by anthropochory (contamination of seed batches or tools). The precautions required to avoid this represent efforts that vary on a case-by-case basis (Chicouène, 2004b). When a species is reintroduced, the speed of recolonization of a field, i.e. the number of possible years for multiplying crops, depends on the density of the fresh contamination, the biotic potential of the taxon and the repression level of the control practices brought back into use for cleaning.

Special cases

The allelopathic after-effects of a plant Whether they are weeds or crops, residues of individuals of certain species undergoing decomposition in or on the soil are known to have allelopathic properties (Singh et al. 2005;[START_REF] Albuquerque | Allelopathy, an alternative tool to improve cropping systems[END_REF]. These properties act both on weeds and crops. The study by Izzet Kadioglu and Yusuf Yanar (2004) on 22 species shows differences in selectivity. The compounds concerned may have been released into the soil while the organs were alive, or they may be produced during decomposition of the individual or of organs (Soufan and Al Mouemar, 2009;[START_REF] Albuquerque | Allelopathy, an alternative tool to improve cropping systems[END_REF]). These effects may originate from plants that grew in the same field, but could also originate from spread litter in the second case (e.g. rye straw mulch) possibly coming from another field. When the mode of action is the inhibition of germination, the risk is that these diaspores emerge when the allelopathic effect ceases. If this emergence happens in the crops where they are the easiest to destroy during the rotation (e.g. in a hoed crop, assuming that the preceding wheat crop was protected by the after-effect of a buckwheat crop) then the rotation is justified.

These notions are listed in figure 3. Logically, the cleaning of the stock of diaspores only exists for those whose lifespan is inferior to that of the inhibition of germination. Knowing how long the two types of effect last and what the spectrum of activity is for each very allelopathic plant would be valuable for improving the design of rotations. Research into their kinetics should also be considered in the context of experimental cultural successions. -Occasional plowing, with jointers to facilitate turning of the cultivated soil, acts on diaspores causing superficial emergence that have life spans inferior to the interval between successive plowing operations or to the time interval between their production and the plowing. However, many studies show that burying tends to increase the persistence of seeds to a greater or lesser degree depending on the species [START_REF] Buhler | Expanding the context of weed management[END_REF].

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-Soil disinfection (by thermal methods such as steam or solarisation or by chemical methods) destroys the diaspores causing superficial emergence irrespective of their usual survival span.

These two techniques prevent emergence from stock located at depths greater than the emergence depth limits of a proportion of the taxa. Effectiveness only lasts so long as there is no reintroduction or reinfestation of the superficial zone. Tools that cultivate the soil to depths greater than the disinfected depth or the depth of origin of emergence (some tined cultivators) could a priori neutralize or reduce the performance of the two operations mentioned.

Taking chemical control into account.

From the point of view of weed science, a crop type is characterized by its cultural practices.

With the expansion of chemical control, [START_REF] Chicouène | Weed control approaches in 51 weed science handbooks[END_REF] notes that several authors of recent textbooks only separate crops from one another by the herbicide programs adapted to each crop. This attitude is at the limit of cultural control described in table 6 (lines 3.1b and 3.2). Within a rotation, the impact of the herbicides is integrated into the impact of the crops in the articles by [START_REF] Anderson | Managing weeds with a dualistic approach of prevention and control[END_REF], [START_REF] Andrade | Weed communities respond to changes in the diversity of crop sequence composition and double cropping[END_REF], Colbach et al. (2017) or considered separately by [START_REF] Singh | Handbook of sustainable weed management[END_REF]. [START_REF] Martin | Pourquoi tant de lianes ? Le cas de la canne à sucre à La Réunion. Congrès sucrier ARTAS / AFCAS[END_REF] even proposes to extend the notion of mimicking weed to selection by chemical control. In light of the fact that the available chemical arsenal varies over the years, observations on the impacts on the crops tested should be interpreted according to the spectra of activity of each herbicide used during the trials.

Temperate climates.

In temperate type seasonal climates, planting of annual crops is spread out over the seasons: therefore, in table 6 (eleven references in line 4.5 and one case in 6.1), the sowing and harvesting dates shown are the four seasons "winter, spring, summer, fall", with variable successions between them.

In a field, evergreen weeds generally coexist with other weeds with various seasonal types of vegetation (especially winter and summer plants). Chicouène (1992) has therefore elaborated a typology of calendars of emergence compared to various seasonal crop cycles. The rotation between spring and fall crops ought to affect very seasonal weeds, but should not act directly on evergreens. The latter are indirectly concerned when the control methods (e.g. mechanical stubble plowing as described by Chicouène, 2007c) show varying effectiveness depending on the seasons: so for an intercrop without plowing (see Chicouène, 2000a), mechanical stubble plowing only causes desiccation of the stolons (e.g. Agrostis stolonifera) in dry summers.

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Intercrop management will also affect weeds that multiply mainly in winter. Arrhenatherum bulbosum produces corms mainly at the end of winter (in March in the northern hemisphere -see Leclerch, 1976), whether or not there is a crop in a vegetative or resting state (case of mown alfalfa mentioned by Chicouène, 2007a). Multiplication may also occur in a winter intercrop, i.e. during the season preceding a spring crop. A rotation including spring crops will only be effective if winter intercrop interventions interfere with corm formation.

A crop calendar may be cleaning for one seasonality type and dirty for another [START_REF] Anderson | Managing weeds with a dualistic approach of prevention and control[END_REF]Chicouène, 2007a). For example with plowing, a spring crop without multiplication of winter weeds with spring reproduction and diaspores with a life span of less than a year (e.g. various annual Bromus) will clean for Bromus and multiply summer weeds, similarly, Arrhenatherum bulbosum corms depend on the management of the winter intercrop, production of Calystegia sepium rhizomes and seeds (which grow at least in any crop remaining in place for six months) depends on the management of the summer intercrop.

Crops may be planted throughout the year, but earlier or later planting dates (by just a few weeks, see table 4.1) with respect to a reference date (the optimum for a given crop) have an effect on some taxa. The latter may prove to be distinct enough from the point of view of seasonality, both in fall crops (see [START_REF] Colbach | Using a sensitivity analysis of a weed dynamics model to develop sustainable cropping systems. I. Annual interactions beween crop management techniques and biophysical field state variables[END_REF] and spring crops (Chicouène, 2007a and2016) or cover crops [START_REF] Baraibar | Growing degree days and cover crop type explain weed biomass in winter cover crops[END_REF].

When a crop planted in a given season contributes to cleaning of weeds multiplied by a crop in another season, the number of successive cleaning-type years logically depends on the duration of the target stocks. Therefore, in a particular situation, [START_REF] Anderson | Managing weeds with a dualistic approach of prevention and control[END_REF] concludes by favoring the alternation between two spring crops then two fall crops in order to control major weed species whose stocks last for approximately 12 months in the two cases of seasonal cycles.

General discussion

Cultural practices are present to a greater or lesser degree for each crop, or even between successive crops, each having more or less variability depending on the crops or the cropping plans.

The aim is to strike a balance between the perspectives that they offer with respect to the flora of a field or region. They may be presented independently from one another or combined with other cultural practices or other methods of management.

Comparison of independent practices

It is easier to start by considering each practice individually, as if interactions did not exist. This approach also corresponds to the oldest documents in the supplementary file. With time, the Chicouène.

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proportion of empiricism decreases, leaving more scope for understanding the phenomena and the issue of regrouping data that at first appear to be contradictory.

Historical descriptors of cultural practices

Before the era of chemical control, the characterization of cultural types was based on categories that were not unanimously approved by the authors in the supplementary file. The resulting ideas may be summarized as follows:

-focused on a single cycle and at the same time with respect to mechanical control: hoed crops (where selective mechanical methods are most easily implemented and are generally essential for crop management) versus competitive crops (where management up to the harvest is usually possible without mechanical intervention). The notion of a "competitive crop" [START_REF] Lee | Weed control under conservation agriculture in dryland smallholder farming systems of southern Africa. A review[END_REF] corresponds to a crop that should be able to cope in a dirtier field.

-specific to the organization of cultural successions, contrasting between dirty and cleaning practices.

Combining these two series, each of which has two qualifiers, should lead to several theoretical situations. As these entities remain imprecise and qualitative, or even subjective, they are at best relevant for extreme cases of crops (the expression of the quantitative aspect using "competitive ability" nonetheless appears in certain references inline 4 of table 6) and for fields with limited flora, they do not necessarily concern the entire flora in a field but only the biological groups defined for each case. [START_REF] Jabran | Non chemical weed control[END_REF] emphasize that the "competitive crop" category corresponds to either "weed tolerance" or "weed suppression" in crops. A destructive or cleaning crop with respect to a species means both that the species is prevented from reproducing and that the species has a diaspore life span that does not exceed the crop cycle. These notions may be used to classify all the practices described. At present, due to the control methods developed during recent decades, they can aid thinking in the light of a large number of possible combinations between crop and weed descriptors, on condition that one does not restrict oneself uniquely to mechanical methods as was the case in the past. All the criteria used to classify the practices described, whatever the age of the publication in which they are described, complement one another within a scale of approach. At the same time, the two series of lists (i.e. on the one hand tables 3 to 5 and section 2.1.2, on the other hand, table 6) resemble one another: the main differences concern the greater role of the characters of cultivars within a species and the much smaller role or absence of chemical control in the first series. These lists of compiled cultural practices remain open. Except for mechanical methods that affect the soil, the practices compared are usable in no-till or soil conservation agriculture.

Descriptors of practices and descriptors of biological targets

The two lists of descriptors of cultural practices compiled from the bibliography are established for practices considered on a single cycle and for the organization of a cultural succession. The notion of the biological target that serves to describe, understand and interpret the effects of cultural practices (column D in table 7) emphasizes the following duality:

-when reasoning on a single cultural cycle, the corresponding biological targets are nearly as numerous and independent as the types of practices.

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-when considering cultural successions, in the general case (line 4 in table 7), the description of cleaning depends mainly on the life span of the stock of effective diaspores, i.e. a single descriptor.

In special cases such as the introduction of a plowing operation or disinfection of the soil (respectively lines 6 and 5 in table 7), the depth of emergence is respectively the second or only descriptor.

The speeds of action of the interventions or practices (column E in table 7) are variable: the shortest is "instantaneous" (exclusive in three lines near the bottom of table 7), then they become more or less intermediate within a cultural cycle, and they may reach up to several years for the possible exhaustion of certain stocks of diaspores (depending on the practices and the type of diaspores targeted) within the limit of the duration of the rotation. In parallel to the effectiveness, problems due to the consequences on the targets and their reverse effects after several years can appear in many situations. For example, the action of some changes in soil physico-chemical properties may last for many cultural cycles. In addition, the issue of the persistence of action for the effects of a practice targeting a single cycle occurs mainly on the scale of cultural successions via the dynamics of the spread of infestations between and within fields. The management of a cycle or an intercrop also has effects on the following cycles, but only when the production or introduction of diaspores are significant with respect to the initial stock in the field and risk being difficult to control.

Levels of knowledge of the effects by practice.

Knowledge about each cultural practice can be on three possible levels:

(1)-Empirical practices, generally traditional, with an ill-defined scale of perception, which are not necessarily optimized. They often date to before the development of herbicides in the 20th century. However, recent techniques are spreading, with the rise of management without plowing, at the same time as equipment is improved in the developed countries. Agronomy textbooks generally provide little information on these cultural methods. A few investigations have been performed on some weeds in geographically limited entities, for example, certain data in [START_REF] Colbach | Reduced herbicide use does not increase crop yield loss if it is compensated by alternative preventive and curative measures[END_REF].

(2)-The "plot level" in the classification of [START_REF] Lichtfouse | Agronomy for sustainable agriculture. A review[END_REF] remains rare for cultural control, and, depending on the objective, the trial is carried out solely between weeds or with the accompaniment of crops, with natural or artificial contamination. Results of rotation and mulching with respect to major weeds are compared by [START_REF] Lee | Weed control under conservation agriculture in dryland smallholder farming systems of southern Africa. A review[END_REF]. To ensure later 516 interpretations comparing weed characters, it is essential to reason by taxon or by biological group or target, not simply by the overall flora in the trial. Here are some examples:

-barley harvest at two sowing densities with the added weed Avena fatua in two trials by Cussan et al. (1976).

-in their trial, [START_REF] Drew | Weed suppression ability of three winter wheat varieties at different row spacing under organic farming conditions[END_REF] mention certain weeds that do not respond in the same way as most of the others to different parameters of crop competition (e.g. height).

(3)-The understanding of numerous biological mechanisms operating within cultural cycles.

Knowledge of these, more or less precise, is likely to contribute to the adjustment or improvement of the practices originating from the two categories mentioned above. For example, [START_REF] Bertholdsson | Use of multivariate statistics to separate allelopathic and competitive factors influencing weed suppression ability in winter wheat[END_REF] proposes a protocol to separate allelopathy from the competition. These interpretations serve, on the one hand, to facilitate the possible interpolations and extrapolations based on some in-depth experimental studies that have already been performed, on the other hand, to propose new trials to test original hypotheses for improving techniques.

Databases on the effects of each practice.

Possible improvements of production methods are concerned on the one hand with knowledge levels gained via experimentation, on the other hand with the creation of databases of some descriptors of weed biology (4th column in table 7, particularly diaspore survival curves and their use for choosing successions).

The mechanisms involved in the effectiveness of any cultural method may a priori be multiple:

-an indirect response to other control methods used simultaneously in the field (e.g. mechanical practices, either with limited selectivity in a hoed crop whereas they are absent in a smothering crop, or in the time interval between two crops), -a simple physiological action (e.g. linked to the phenology of each taxon),

-interference with crops or other weeds, -biological regulation by parasites, etc.

The different levels of information that have just been discussed are not all shown in the supplementary file or in tables 3 to 5, they may be compiled in an encyclopedic database thanks to the traceability of the bibliography. The aim is to centralize expert observations and experimental knowledge in the form of thematic databases. Mathematical modeling could be considered from the last two levels conjointly. The selection of flora in the field is a risk, as for any crop protection

Chicouène.

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practice. For each practice, a distinction should be made between plants that are just spared (nontarget), and the variations around an optimal cultural cycle including weeds with cycles opposed to the target (tables 4 and 5).

Accumulation and combination of cultural practices

Types of relationships in combinations of cultural practices

Combinations of cultural practices a priori lead to three types of interference: positive, neutral or negative.

-The accumulation of effectiveness of cultural practices is reported in some trials by [START_REF] Singh | Handbook of sustainable weed management[END_REF] and [START_REF] Anderson | Managing weeds with a dualistic approach of prevention and control[END_REF] for floras reduced to a few species. In soil conservation agriculture, the effects of combinations of cultural practices are reported on a few species. And on mixed scales, i.e. on the one hand on one cycle and on the other hand on a succession, [START_REF] Borger | Eleven years of integrated weed management: long term impacts of row spacing and harvest weed seed destruction on Lolium rigidum control[END_REF] test closer row spaces and destruction of seeds at harvest, whereas [START_REF] Jabran | Non chemical weed control[END_REF] consider the combination of "cover crops, mulch and rotations".

-Some combinations appear to be useless due to redundant mechanisms or actions. In particular, strict mimicking weeds are vulnerable to several interventions designed to purify crop seed batches. This is also the case for plowing following the suppression of chaff and a low-cut harvest for diaspores with emergence from shallow origins (e.g. Bromus secalinus a mixed mimicking weed if without plowing, or if a late spring crop follows -Chicouène, 2000a).

-Negative relationships exist for several reasons. The disadvantages of many practices (last column in tables III to V) and mechanisms of action are such that the effects cancel each other out.

In other words, the two practices applied together to become ineffective. For example, the avoidance of harvest of the stock by late threshing after maturity is contrary to a cleaning rotation.

Similarly, high sowing density would hardly be compatible with a tall cultivar or with heavy fertilization because of the high risk of encouraging climbing weeds (phenomenon suggested by the results on Galium aparine quoted by [START_REF] Drew | Weed suppression ability of three winter wheat varieties at different row spacing under organic farming conditions[END_REF] and then that of crop fall (which then encourages short heliophilous weeds as in the absence of a tall crop or as for a mulch).

Choice of combinations of practices in trials.

The numerous descriptors of cultural cycles multiply their possible combinations at the scale of a rotation. Even when just a few classes of states are considered for each descriptor, comparisons of the spectra of action lead to huge numbers of choices. Already, for one cycle, the implementation can differ from the phytotechnical optimum via several tens of dimensions. Data sometimes exists for pairs of practices or more. At the scale of a single cultural cycle, two descriptors are often combined, with each having several states: sowing and fertilization dates are quoted by [START_REF] Lee | Weed control under conservation agriculture in dryland smallholder farming systems of southern Africa. A review[END_REF] in South Africa. In Iran, [START_REF] Koocheki | Effect of cropping systems and crop rotations on weeds[END_REF] compare a flora of 24 taxa under three rotations with two crop-planting seasons. This operating approach is only relevant for practices without disadvantages, so for most practices, it is more complicated. In addition, due to the variable effectiveness of practices and variable targets, the alternatives are:

-either to focus on the intensity of a single practice known to be potentially very effective on the target taxon, -or to combine several practices with the same taxonomic selectivity when each has limited effectiveness.

Understanding the mechanisms of action of each practice independently from those of other practices seems to be important when the main aim is to control the risks of combinations with negative relationships. The search for precautions when organizing combinations of interventions ought to be a priority with respect to the most harmful taxa in a field. Given the possible selections, all the flora of the field or the geographical area being considered should be taken into account. It is necessary to have at least minimal knowledge about the states of complementary biological descriptors for the flora and their various relationships with the descriptors of types of crops.

The case of meadows:

Simple choices between combinations of alternatives are illustrated by temporary grasslands because the weeds present have few cultural descriptors (2nd line in table 7 andChicouène , 2007b). Their type of dirtying depends on vegetation heights before and after each cycle of exploitation, parameters which are themselves dependent on the production calendars. The last year is sacrificed from the point of view of diaspore production as these are easily eliminated in the following crops. In pure alfalfa in temperate climates, taxa with winter development and reproduction (strict winter weeds and short-lived evergreens) are limited by three solutions:

-either an associated crop for the winter against heliophilous weeds with slower growth than this crop, -or control by another method (e.g. mechanical),

-or allow them to multiply and in this case, avoid fall crops after the alfalfa for a number of years that depends on the life span of the diaspores produced (i.e. at least two years with Arrhenatherum Chicouène.

519 bulbosum corms). However, fall crops become possible by using alternative control methods that are not strictly cultural.

Strategies and relationships with non-cultural methods

Cultural methods in general control strategies

Control strategies can be globally organized according to the four examples compared in table 2, which are not necessarily limited to cultural methods sensu stricto. The first three, in particular, are closely linked to successions. If a cleaning strategy leads to eradication in a field, the probability of reintroduction of the taxon depends on cultural methods, but also on landscape factors for certain types of dissemination. On the other hand, exchanges from reservoirs of biological regulators outside the field should be considered on a case-by-case basis (Chicouène, 2004b). Within a field, cultural practices always exist. It is useful to understand their effects with the aim of coordinating them with the other control practices available. In integrated control, an association of different control methods in addition to cultural methods is often recommended [START_REF] Anderson | Managing weeds with a dualistic approach of prevention and control[END_REF][START_REF] Borger | Eleven years of integrated weed management: long term impacts of row spacing and harvest weed seed destruction on Lolium rigidum control[END_REF][START_REF] Lee | Weed control under conservation agriculture in dryland smallholder farming systems of southern Africa. A review[END_REF][START_REF] Jabran | Non chemical weed control[END_REF].

Strategic indications mainly concern a few species, with an approach that is often monospecific:

-28 weed control textbooks out of the 51 compared by [START_REF] Chicouène | Weed control approaches in 51 weed science handbooks[END_REF] mention the main methods usable against several dozen taxa in general, usually including the possibilities of certain cultural practices.

-Several articles describe multiyear monitoring of trials on one species to optimize certain strategies used to accompany cultural methods. Here are four examples: on Alopecurus myosuroides, Colbach et al. (2020), using the ALOMYSYS model, compare "crop sequence", several cultural practices sensu stricto, "optimal herbicide spraying, moldboard plowing"; on Lolium rigidum, [START_REF] Borger | Eleven years of integrated weed management: long term impacts of row spacing and harvest weed seed destruction on Lolium rigidum control[END_REF] small number of cultural practices and other methods each time. They rarely bring to light or explain the possible existence of taxa with opposite reactions to certain practices, or their place in the management of a set of flora. In addition, concerning the details of the overall annual species, flora in fields in limited regions, Colbach et al. (2017) and [START_REF] Colbach | Reduced herbicide use does not increase crop yield loss if it is compensated by alternative preventive and curative measures[END_REF] collect data on certain cultural practices together with other practices in the FLORSYS model and consider the probabilities of "overall high performance" for each "strategy", by discussing the "correlation between cultural practices". The prospects opened by this approach should be developed to encompass the total flora of fields using the many cultural methods summarized in table 6.

Types of interference between selectivity mechanisms

An assessment of the advantages and disadvantages of practice with respect to another having common points of taxonomic selectivity obviously goes beyond cultural methods alone, but the mechanisms demonstrated for the latter should be compared to those of other methods. The question of the global strategy against weeds in a cultural system arises for any control practice, whether cultural or not, i.e. all the practices applied or applicable in a field. In parallel, the three types of relationships discussed for the combination of cultural practices between themselves can be extended to combinations between cultural and non-cultural practices. The analysis of the mechanisms of selectivity involved will also be used to assess the advantages and risks, taking account of the inherent disadvantages of several cultural practices and the types of interaction.

When targets are quoted in the literature, they are usually only taxonomic and also limited (e.g. in [START_REF] Singh | Handbook of sustainable weed management[END_REF]. The assessment of the effects of one or several cultural practices amongst other methods appears in some monospecific studies already quoted in § 4.3.1. The relationships assessed here are mainly accumulated effectiveness. The types of interference (four groups in table 8) with non-cultural methods may vary according to the practices when considered in pairs, and according to their targets and counter-targets. In short, it is at the scale of a sufficiently large phytogeographical zone that substitutions of methods should be analyzed, and on a sufficiently long time scale to exclude possible ephemeral correlations between the effects of a crop and the effects of the herbicides used on it during the years of study.

Negative interferences between cultural and other methods may occur in both directions, depending on the chronology of the actions:

-direct: for example, mechanical interventions that deeply work the soil will more or less cancel out the effects of methods that provide surface cleaning for species emerging close to the surface that still have deeply buried viable diaspores.

-indirect: some cultural methods could disturb pre-existing biological regulations. Their action is often considered to be complex since [START_REF] Pammel | Weeds of the farm and garden[END_REF] and difficult to predict (Upadhyaya et al., 2007: 27). This risk of negative interactions requires knowledge of the mechanisms of action of each cultural practice. If it acts via a biological regulation, it could be disturbed by another cultural

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intervention. The assessment of its conditions of effectiveness should aid the choice of when to take them into account.

Comparison of descriptors between cultural and other methods

The multiple mechanisms and biological targets of cultural methods are more complex to understand than those of uniquely mechanical methods. The latter is reduced to a few general principles, mainly architectural, outlined by Chicouène (2007c) on the basis of two main and opposed mechanisms (exhaustion of energy reserves as opposed to desiccation). The actions of plowing with respect to biological forms and soil and climatic conditions are shown by Chicouène (2000a). Two types of extreme targets are described by their architecture (depths of formation and emergence), i.e. limiting of stoloniferous weeds in the dampest and most asphyxiating conditions, deep underground organs regrowing elsewhere. These comparisons between the architectural descriptors of two types of traditional methods connect two extreme types via several descriptors, at least in temperate climates (Chicouène, 2000a(Chicouène, , 2007a(Chicouène, and b, 2016)):

-short stoloniferous heliophilous weeds, which are advantaged by damp soil and climate conditions and by low-growing crops or intercrops. These are difficult to control by stubble plowing, but limited by plowing, -tall vigorous weeds, with emergence from deep origins (diaspores with substantial energy reserves), in deep healthy soils, which are capable of growing through a layer of ploughed soil as well as a layer of dead mulch, or even a tall cultural ground cover.

Thus, numerous parameters of foliage and depth of emergence become common descriptors for the implementation of several groups of control methods: in addition to cultural methods, they are used a lot for other methods, at least for mechanical and chemical control. For all the strategies, population forecasts according to the biological diversity of the diaspores (Chicouène, 2004a) are a crucial step for decisions concerning cultural practices and several other types of practice. A database of weed biology destined for dirtying forecasts and cultural control could be useful for the combination with other management methods, especially in view of the fact that many descriptors simultaneously determine several methods. The logical idea would be to contribute to the coordination with other methods by comparing the targets. As far as landscape factors are concerned, these intervene directly by the transfer of weeds between fields, particularly mimicking weeds and easily cleaned weeds (Chicouène, 2004b) and indirectly on the source of biological regulation. In parallel, the subject of the exploitable level of population for biological regulation is primordial: while its effectiveness is sometimes proportional to the density of the taxon (e.g. Westerman et al., 2008;Baraibar et al., 2011), then this phenomenon, when it is effective on certain species, is likely to call into question classical notions of cleaning that aim to minimize stocks of diaspores rather than harmfulness, or even the search for added effectiveness. These relationships, which can also be exploited for the management of biodiversity, are an indispensable theme for models of sustainable agriculture or agroecology. This would be a complement to the "multiobjective" approach of Colbach et al. (2017b and2017c) on biodiversity.

Conclusion

The cultural methods listed are organized from references which each have a number and a variable classification of practices, they all group together criteria of choice of cultivated species or cultivars and management of fields and their successions. Finally, they are shown at two distinct scales of issues. In one, there is no absolute limit with other types of control methods: this is the strategy in the succession of management of cultural cycles (all control methods considered), generally over several years, in other words, it is the way in which the different practices are made to follow one another in successive crops that defines the character of cultural control. In the other scale, when taken strictly, i.e. considering a single crop cycle, cultural methods do not encompass the other control methods, with the possible exception of a biological regulation that would depend on them, or even (at the limit) on selective mechanical interventions allowed in some crops. The particularity of most of the many practices of cultural control is the risk that they may encourage weeds opposite to the target. This widespread duality justifies two consequences:

On the one hand, the aim is to avoid the case where a protocol with a global assessment concerning all weeds, without identification, would logically lead to an opposite conclusion when this flora corresponds to an opposite biological target. Proper exploitation of studies on cultural practices absolutely requires presentation of the results for known biological targets (or they could at least consider later by means of detailed results by taxon).

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-On the other hand, databases on biological descriptors of the flora need to be adapted sufficiently to ensure the employment of notions that are more finely tuned than a simple balance between immediate benefit and cost.

For some biological forms, effectiveness may possibly be proportional to the intensity of the efforts around the phytotechnical optimum of a crop, a cropping plan or a cultural system. In order to best identify the issues involved, practices whose mechanisms of action rely uniquely on hypotheses with little documented evidence should be clarified, particularly as concerns the quantitative relationship between an essential descriptor and the corresponding target.

The most important biological descriptors of targets require a consensus, but one difficulty is that some recent syntheses on cultural methods do not mention knowledge recognized in older weed science documents. Excluding such ambiguities and the necessity to rehabilitate some knowledge, the explanation of the diversity of all existing cultural methods highlights the wide range of possibilities available. Strictly speaking, the lists of targets defined by practice should be considered in the operation of agricultural systems. This is a step towards improved technical expertise, logically as for any method of flora management.

Stephen 1982 Control without herbicides: flooding 66; burning 66-67; mulching 68-69. (intercropping, rotation (competitive vs. non-competitive corps, perennial phases, alfalfa, winter vs. summer crops), cover crop, undersowing, summer fallow 309 ; graze weeds 309; mulching 309-10; composting 310-1; fertility 311-4.

Zimdahl 1993

Seed dispersal: storage manure 72-74; machinery (clean seed, combines,...) 74-76. Buhler & al. 1997 Increasing crop competitiveness / breeding: (crop tolerance and crop interference; selection criteria, critical events in crop and weed life cycles, plant residues) 59-76. Genetic of cover crops: components of interference, characteristics amenable 77-93. Soil quality: interspecific interference (species specific), fertility management, cover cropping and green manuring 95-121. Soil seed banks: prevention of seed introduction on farm (crop seed, manure...) 150 ; decision about seed levels (eradicate, decrease, tolerate) 151-152 ; strategy seed populations (active to dormant, dormant to active, undesirable to desirable species 152-154. Multiyear model / crop and tillage conditions (rotation sp., herbicides) 207-224. Levels of integration / weed management: scale (spatial, temporal), method, knowledge base, crop rotation, herbicides... 239-267. [START_REF] Radosevich | Weed ecology, implications for vegetation management[END_REF] Methods and tools of w management 335-395: prevention (inhibit establishment in areas : cultural (seed cleaning)), eradication from field-area, control, reduce W 335-336, methods ; physical 347-377 (hand, fire, flame, tillage, mowing, flooding, mulches, solarization), cultural 377-378 (prevention (crop seed, manure, harwesters...), crop rotation 378-379 (different crops from year to year, certain sp. associated with particular crops, solid-seeded crop like alfalfa or cereals to a row crop like..., different cultural techniques, crop production vs. fallow), crop competition 379-381, cover crops 381, harwesting 381), biological 382-387 (grazing, mycoherbicides, allelopathysmother crops). [START_REF] Liebman | Ecological management of agricultural weeds[END_REF] Soil environment 210-268: ... fertility 220-229 when W exhibit stronger height and leaf area responses to fertilizer than do crops : fertilizer = negative effect, placement of fertilizer reduce W density 223. Competitive ability of crops 269-321: crop density 270-281 (curves), spatial arrangement 281-287, crop genotype 287-297 (breeding for competitive ability : selection characters correlated with competitive ability is more efficient than selection on competitive ability), phenology 297-304. Crop diversification 322-374/ crop diversity, rotation 326-336 (crop management practices, with or without herbicides, perennial forage crops (Elytrigia repens: density should be reduced during annual crops phases 335), cover crops ; variation in timing of M practices, in soil conditions). 8)Insects and pathogens: pesticides detrimental / biocontrol agents 379. 9)Livestock grazing 409-443. Monaco & al. 2002 IWM: management practices 45 ;scouting 45-46 ; prevention 46 (crop seed contamined, propagules with machinery, manure..., recharge the soil seed bank, aras adjacent to fields, spread of vegetatively reproducing perennial) ; mechanical practices (... mowing 52, mulches 53-56, burning 56, flooding 56-57) ; cultural practices 57-64 (crop selection 57-59), crop rotation 59-60 (sp. ; pastures often contain perennial W such as iron-weed and thistles), changes cultural conditions (planting dates, competiting, fertility, herbicides) ; crop varieties 60-61 ; planting date 61 ; plant population and spacing 63, fertility and irrigation 63-64 (W respond + to increasing nutrient level: better compet with crop). [START_REF] Naylor | Weed management handbook[END_REF] Non-chemical management: cultural (crop rotation -cleaning crop, competitive ley, fallow, intercropping, cover-crop-, choice of cultivar, plant spacing, limiting the introduction -farm machinery, crop seed-,...) 280-286 ; direct management (steaming, solarization, mulching, living mulches, sheeden mulches,...) 286-294. Integrated management: crop rotations (timing of sowing, canopy development, harwesting), choice of variety, seed purity,... crop nutrition strategy 307-308. Winter cereals: rotation (winter vs. spring sowing, sp., herbicides), sowing date (early vs. late sowing), crop competition... 355-356...

Hakansson 2003

Plant adaptation and competitive conditions: W flora / fertilizer use 119-121: [sp.] many observations: W declined respond positively to fertiliszer in absence of competition from crops but negatively in dense crop stands ; some W (Chenopodium album) obviously often more favoured by high fertilizer levels than the crops ; competitive conditions in different crops 121-123. Special management measures 214-221/ Cover crops (breakage by mechanical +-herbicides) and mulches (mulch large: small and large-seeded W different influenced ; seedlings from small seeds have greater difficulties in penetrating). Harwesting -timing and methods 217-218: variation = diversified crop sequences ; later harwesting = stronger selection between early and late maturing seeds ; tall stubble = more W seeds left in the field + Elymus repens younger, more active shoots largely escape cutting ; roots crops: breakage of vegetative parts of perennial W, time of year is decisive. Breeding for increased competitive ability of crops 218-219: crops exerts a stronger competitive effect as a result of more rapid ground cover ; degree of cv. shaded the W in decisive growth period ; selectively acting substances. Biological control 219-221: augmentation strategies, system management. [START_REF] Saraswat | Weed management[END_REF] Factors / crop-weed competition: moisture, nutrients 39-41 ; effect of weed and crop density ; weed sp. ; crop sp. ; fertility ; crop sequences, rotating crops (sp.) 44-48. Agronomic practices: planting or sowing time, clean seed, stale seed bed, row spacing, seed rate, crop rotations (sp., smothering, transplanted rice), intercropping, mulching, water, nutrient 75-86. In cereals: rice, cultural (stale seed bed, flooding) 184-185 ; maize, cultural (crop rotation, higher plant population, early application of nitrogen and its placement, mulching, intercropping with smoother crops) 186 ; wheat, cultural (stale seed bed, higher seed rates, closer spaceint, rotations) 191 ; ... In cash crops: cotton: agronomic practices (unlike cereals, early planted...) 199-200... [START_REF] Singh | Handbook of sustainable weed management[END_REF] Weed management: cultural methods (competitive crops 5 ; crop rotation, use of cover, smother crops, genotypes better competitive and allelopathic, sowing and planting dates, crop density 6) ;

  humidity and contamination of the harvested batch by Avena fatua at the milky stage 3b) -harvest delayed by a few days at the harvester the batch harvested is purer and drier because the targeted diaspores have mostly fallen onto the soil input to the soil stock from the weeds targeted in the preceding column 4) cutting height: (Hakansson, 2003; Chicoue ne, 2016) 4a) high cut (less straw to pass into the combine harvester) limits the entry of dwarf plants into the combine harvester (limits blocking of the blades)input to the soil stock from the weeds too low to be cut,[START_REF] Hakansson | Weeds and weed management on arable land : an ecological approach[END_REF] 4b) low cut with crop lifters (lots of straw filling up the combine harvester)can avoid the input of just-ripe diaspores to the soil, especially: -fallen mimicking weed individuals -

Figure 1 .

 1 Figure 1. The cycle of a crop compared to that of a mimicking weed.

Figure 2 .

 2 Figure 2. Main parameters of a cultural succession focused on diaspore stocks (Chicouène 2006 modified).

Figure 3 .

 3 Figure 3 . The three mechanisms of allelopathic after effects in a cultural rotation.

Table 1 .

 1 Inventory and mechanisms of cultural control practices … 492 Classifications of crop rotations as strategies from 25 weed science textbooks amongst the 42 in the supplementary file.

	Notions of strategies	Classification as cultural	Reference
	1	"eradication"	-	Brenchley (1920) with only "cleaning crops" (rotation not explained)
	2	"extermination"	-	Pammel (1911)
	3	"destruction"	-	Shaw (1892, 1893)
	4	"control, destroying"	-

Table 2 .

 2 Comparison of 4 levels of reasoning for preventive and curative strategies (extract from Chicouène 2000b, with additions).

	Examples of levels of reasoning:	A. preventive:	B. curative:
	1. Presence of the taxon in the field	avoid any introduction of troublesome new taxa	eradicate the taxa (when this is feasible and important)
	2. Stock of diaspores	prevent a stock from increasing	reduce a stock
	3. Make provision (or not) for the next crops (or years)	limit the populations for the next crops and/or years	prevent the harmful effect of the vegetation in the existing crop
	4. Development of the vegetation in the existing crop	intervene as soon as possible (on seedlings, at germination or when growth restarts)	intervene (just before harvest) on mature plants or when sorting the harvest

Table 4 .

 4 Cultural practices with simple actions, with disadvantages in weed science(Chicouène 2016 modified).

	Practices, cultural descriptor	advantages, targets	disadvantages, limits
	1) change the soil's physico-chemical properties to adapt it for a crop (Chicoue ne 2016), soil conditioners

Table 6 .

 6 Classification of the main descriptors of crop rotations in 36 weed control textbooks.

	no.	Implicit group of descriptors	Descriptor of crops in rotation	Quoting of practices and reference
	1.	crops only	cultivated taxa

Table 7 .

 7 General comparison of the issues of biological weed targets by groups of cultural methods

		A	B	C	D	E	F
	No	Levels of reasoning:	Aim:	Methods-practices:	Targets: numbers, types of descriptor	Speed of action:	Limits and disadvantages:
	1.	1 cultural cycle, (including mimicking weeds at the vegetative stage)	minimize harm in the coming harvest	cultural sensu stricto, sometimes includes certain other selective practices (e.g. hoeing)	numerous (28 targets in tables 3-5 = -morphological: architecture, height of organs, etc. -eco-physiological -phenological	depending on the practice, ranges from the cultural cycle, to just the harvest operation	disadvantages in about the same numbers for targets and +-opposed to the target (tables 4 and 5)
	2.	temporary grassland	minimize harmfulness or the stock	height before and after an operation	few (in Chicoue ne 2007b), especially height of vegetation before and after operation	at least one operation cycle	selectivity reduced with respect to the crop (permanently present)
	3.	mimicking weeds contaminating a batch of seeds and its cycle	minimize the populations of mimicking weeds	" harvesting conditions, sorting of harvested batches (of seeds)	morphological: shapes, dimensions, density of the diaspores	instantaneous	-
	4.	cultural succession in a field: cleaning	minimize a stock of diaspores that have an effect in futures crops	c. all methods	on the 17 groups in table 6: one essential target descriptor in fig. 1 (duration of diaspores that are not renewed)	-the life span of the targeted diaspores -duration of inhibition from allelopathic after-effects	independent of the target, recolonization: -reintroduction -speed of spread
	5.	a succession of practices between two crops	"	soil disinfection (without extra mixing)	1: depth of emergence with respect to the depth of disinfection	instantaneous	" + danger of deep tillage of the soil
	6.	"	"	occasional plowing, not every year (without extra mixing)	2 (in Chicoue ne 2000a): duration of the emergence diaspores + depth of	"	"

Table 8 .

 8 A priori examples of types of interference between cultural and other practices

	Type interference impossible (incompatible practices) only negative all types (-, 0, +) without direct interference (possible complementarity by substitution of taxonomic spectrum)	cultural sensu stricto mechanical p.p. (e.g. living permanent ground cover with respect to plowing when planting the crop) _ biological + landscape (open could sometimes encourage the introduction of auxiliaries) chemical (may allow avoidance of dilemmas of cultural practices with two extreme states with taxonomic selectivity that is partly common)	rotation mechanical p.p. (e.g. living permanent ground cover with respect to stubble plowing between 2 crops) breaks the biological regulation within the field landscape (open encourages the introduction of some weeds) chemical (often increases the taxonomic spectrum of cleaning)

  ; flooding 34; fire 34-5); crop competition (smother crops, competitive crops, crop rotation (e.g. herbicides) 35-39. FAO 1986 (no bibliography) Control: mulching 24; cultural control: crop interference (competitive crop, multiple cropping) 25, fertilizer placement 25, timing plantation, liming 25, rotation (spring / autumn seeded, different herbicides) 25-26. In crops: cultural practices (planting date, seed source clean vs. contamined, fertilization, pasture following harwest, fallow...) 128; cropping patterns (crop, spacing and density, rotation...) 128-129. Altieri & Liebman 1988 Factors weed-crop balance: intercropping: 162-4; cv. effect (potatoes...) 170-2. Intercropping: crop density 205-6; spatial arrangement 206; crop species and cv. 206-7; soil fertility 207. Management systems: dispersal of seeds (contamination of crop seeds 216-7; harvesting equipment 217-8); edaphic factors (soil pH and drainage, irrigation 218-9; soil fertility (N increased or discouraged W sp.; K increased Striga / maize) 219); cultural practices (rotation (different harwesting dates, fooling crops vs. cleaning with mechanical, time planted, graminicides) 220-1; spatial arrangement (row widths) 221-2; straw dispersal + burning 223-4). Management of pathogens and insects for weed control 245-264. Organic systems: timing of field operations 307-8; seeding rate & cv. (soybean) 308-9; cropping systems

	Anderson 1983 Control: preventive (weed-free crop seed) 67; cultural (smother crops, rotation (cultivated crops vs. non cultivated) 71; mowing 72; water management (flooding) 72-73; smothering with nonliving
	material 73; burning 75.
	Gwynne & Murray 1985
	Weed origins: rotations 18 ; seed cleaning 21-22.
	Control Wild oats: straw burning 108, crop rotation (winter cereal vs. spring) 108-109. methods: non-chemical Other weeds: non-chemical (seed-rate, fertilizer, cv., drainage) 117; cultural 126-127.	40-41.
	Ross & Lembi 1985
	Control: mechanical (mowing 31-3; mulches 33-4

Table of contents . . . 1 p. = p.50 c

Acknowledgements

To Henri Darmency (Dijon, France) for his remarks on the manuscript, to Martin Fillan (Hennebont, France) for the translation.

Conflicts of Interest

No conflict of interests has been declared SUPPLEMENTARY FILE I: Main headings for cultural control in 43 weed control textbooks. Key:

-in thick characters = specification of "cultural" -in italic red characters= "rotations", with their descriptors.

-highlighted in yellow: strategy terms -"sp." (for a rotation) = simple reporting of the different species cultivated -"I" = integrated -"W" = weed -"M" = management Shaw 1892 (no bibliography) Principles in destroying weeds 5-9: drop certain crops out of the rotation; eradication / soil and climate; purchasing seeds (in the seeds of clovers, grasses, cereal grains) ; clean machines ; hoed crops as far as practicable ; grow clover and lucerne (smothering) ; keep the land growing crops (ex. 2 crops a year) ; autumn cultivation ; fermentation of the manure.