Prefer post-emergence herbicides over pre-emergence solutions
Post-emergence weed control strategies allow selecting commercial products whose spectrum of efficacy matches the present weed flora. They thus maximize treatment effectiveness. Moreover, they can enable dose adjustments, or even skips, depending on the observed weeds pressure.
Example of implementation:
"Weed management of maize 'all post' in one pass (only on plots with low weed pressure) or 2 passes.
Implementation period On established crop
Spatial scale of implementation Plot
Application of the technique to...
All crops: Sometimes difficult to generalize
The adoption of post-emergence weed control strategies can only apply to crops for which solutions are approved for this use (for sunflower for example, the choice of a post-emergence strategy can only apply to herbicide-tolerant varieties). For some crops, a pre-emergence intervention is often necessary (e.g. oilseed rape), or can only be avoided in plots with low weed pressure (pea, faba bean). This technique is mainly of interest for maize and cereals with straw.
All soil types: Sometimes difficult to generalize
On clayey soils, which favor staggered weed emergence, post-emergence strategies may have limitations due to reduced persistence of treatment action.
All climatic contexts: Easily generalizable
Post-emergence treatment efficacy is less dependent on climatic conditions than pre-emergence treatments.
Regulation
2. Services provided by the technique
3. Effects on the sustainability of the cropping system
"Environmental" criteria
Effect on air quality: Variable
phytosanitary emissions: VARIABLE
Effect on water quality: Increasing
pesticides: DECREASE
Other: No effect (neutral)
Pollutant transfer to water (N, P, phyto ...): Decrease
Adopting post-emergence weed control strategies allows adapting the choice of commercial products and dose to weed pressure. It can thus lead to reductions in herbicide use. Moreover, it can limit the risk of transfer to water compared to a pre-emergence application on bare soil.
Pollutant transfer to air (N, P, phyto ...): variable
Compared to the use of incorporated pre-emergence herbicides, the use of post-emergence herbicides may increase the risk of phytosanitary product transfer to air. This risk depends on the physicochemical properties of active substances, but also on application conditions.
Fossil energy consumption: no effect (neutral)
GHG emissions: no effect (neutral)
"Agronomic" criteria
Productivity: No effect (neutral)
Soil fertility: No effect (neutral)
Water stress: No effect (neutral)
Functional Biodiversity: No effect (neutral)
"Economic" criteria
Operational costs: Variable
The impact of choosing post-emergence or pre-emergence weed control strategies on herbicide costs depends (i) on the unit cost of commercial products and (ii) on the dose used. When adopting a post-emergence strategy leads to reduced doses or skips, it allows a cost reduction.
Mechanization costs: No effect (neutral)
Margin: No effect (neutral)
"Social" criteria
Working time: No effect (neutral)
Observation time: Increasing
Successful post-emergence weed control requires intervention on young weeds, which necessitates regular plot observation.
4. Organisms favored or disadvantaged
Favored Bioagressors
| Organism | Impact of the technique | Type | Details |
|---|
Disadvantaged Bioagressors
| Organism | Impact of the technique | Type | Details |
|---|---|---|---|
| weeds | weeds | Effectiveness depends on the efficacy of authorized products on different species. |
Favored Auxiliaries
| Organism | Impact of the technique | Type | Details |
|---|
Disadvantaged Auxiliaries
| Organism | Impact of the technique | Type | Details |
|---|
Favored climatic and physiological accidents
| Organism | Impact of the technique | Details |
|---|
Disadvantaged climatic and physiological accidents
| Organism | Impact of the technique | Details |
|---|
5. To learn more
- Weed management of maize - Practical guide for farmers
- -CRA Pays de la Loire - Arvalis
Technical brochure
6. Keywords
Bioagressor control method: Chemical control
Mode of action: Catch-up
Type of pesticide use strategy: Efficiency
| Julien Halska | INRA | julien.halska(at)grignon.inra.fr | Epoisses (21) |
| Rémy Ballot | INRA | remy.ballot(at)grignon.inra.fr | Grignon (78) |
Annexes
Défavorise les bioagresseurs suivants
