Spray drift of glyphosate reduces flowering of non-crop plants, limiting resources for beneficial insects

Chemicals sprayed in agriculture can drift from the target field during spray events, impacting human exposure and neighboring crops. A recent study published in the journal Environmental Pollution shows that spray drift can also impact non-crop plants that would normally provide important food resources for beneficial insects like pollinators and natural enemies to pest. Specifically, the study found that the herbicide glyphosate can drift from the target field sprayed, that the drift can be unpredictable depending on weather conditions, and that non-crop flowers exposed to the drift reduce their flowering. The researchers measured the concentration of glyphosate drift at multiple distances from the spray event and found that while the drift didn’t travel that far, the amount of glyphosate deposited was not correlated with distance, indicating that environmental conditions can dramatically influence the amount and direction drift from one minute to the next. The researchers also measured cumulative flowering of nearby and exposed plants, and found that overall flowering was reduced for two important legume plants frequented by beneficial insects: red-clover (Trifolium pratense) and bird’s foot trefoil (Lotus corniculatus). The timing of flowering, however, was not impacted by exposure to glyphosate drift. This study shows that concerns for environmental impacts of spray drift should also include non-target, non-crop plants that provide important floral resources for pollinators and natural enemies to pests. 



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