Editing Herbicide (section)

===Resistance management===
{{see also|Integrated pest management}}
Due to [[herbicide resistance]] – a major concern in [[agriculture]] – a number of products combine herbicides with different means of action. [[Integrated pest management]] may use herbicides alongside other pest control methods.

Integrated weed management (IWM) approach utilizes several tactics to combat weeds and forestall resistance. This approach relies less on herbicides and so [[selection pressure]] should be reduced.<ref name=moss /> By relying on diverse weed control methods, including non-herbicide methods of weed control, the selection pressure on weeds to evolve resistance can be lowered. Researchers warn that if herbicide resistance is combatted only with more herbicides, "evolution will most likely win."<ref name="damalas"/> In 2017, the USEPA issued a revised Pesticide Registration Notice (PRN 2017-1), which provides guidance to pesticide registrants on required pesticide resistance management labeling. This requirement applies to all conventional pesticides and is meant to provide end-users with guidance on managing pesticide resistance.<ref>{{cite web | url=https://www.epa.gov/pesticide-registration/prn-2017-1-guidance-pesticide-registrants-pesticide-resistance-management | title=PRN 2017-1: Guidance for Pesticide Registrants on Pesticide Resistance Management Labeling | date=21 September 2017 }}</ref> An example of a fully executed label compliant with the USEPA resistance management labeling guidance can be seen on the specimen label for the herbicide, cloransulam-methyl, updated in 2022.<ref>{{cite web|url=https://www3.epa.gov/pesticides/chem_search/ppls/062719-00689-20220519.pdf |title=Pesticide Product Label
|website=epa.gov|access-date=4 April 2023|date=19 May 2022}}</ref>

Optimising herbicide input to the economic threshold level should avoid the unnecessary use of herbicides and reduce selection pressure. Herbicides should be used to their greatest potential by ensuring that the timing, dose, application method, soil and climatic conditions are optimal for good activity. In the UK, partially resistant grass weeds such as ''[[Alopecurus myosuroides]]'' (blackgrass) and [[Avena]] genus (wild oat) can often be controlled adequately when herbicides are applied at the 2-3 leaf stage, whereas later applications at the 2-3 tiller stage can fail badly. Patch spraying, or applying herbicide to only the badly infested areas of fields, is another means of reducing total herbicide use.<ref name=moss />

{| class="wikitable"
|+Agronomic factors influencing the risk of herbicide resistance development{{OR|date=December 2023}}
|-
! Factor !! Low risk !! High risk
|-
| Cropping system || Good rotation || Crop monoculture
|-
| Cultivation system || Annual ploughing || Continuous [[minimum tillage]]
|-
| Weed control || Cultural only || Herbicide only
|-
| Herbicide use || Many modes of action || Single modes of action
|-
| Control in previous years || Excellent || Poor
|-
| Weed infestation || Low || High
|-
| Resistance in vicinity || Unknown || Common
|}