North Dakota Research: Dry, Dusty Conditions May Affect Herbicide Effectiveness - UNL CropWatch

North Dakota Research: Dry, Dusty Conditions May Affect Herbicide Effectiveness - UNL CropWatch

May 25, 2012

As is the case in areas of Nebraska this year, dry soil conditions across many areas of Illinois have accelerated both planting of crops and spraying with post-emergence herbicides. Under such conditions airborne dust has been shown to reduce the activity of some foliar-applied herbicides, including glyphosate.

Beware of the Dust, an article in this week's University of Illinois crop pest newsletter, looks at research conducted by North Dakota State University on how dry, dusty conditions can disrupt herbicide activity on weeds, reducing  its effectiveness.  The NDSU research "demonstrated that control of nightshade species with glyphosate was reduced when dust was present on plant leaf surfaces. The reduced phytotoxicity occurred whether dust was present on the leaf surfaces before glyphosate application or deposited there within 15 minutes. If dust was deposited more than 15 minutes after glyphosate application, or if glyphosate was applied 30 minutes before dust was deposited, reduced phytotoxicity was not reported."

While remedies are few, sprayer adjustments may help lessen the decrease in herbicide effectiveness. The NDSU research found that a higher spray volume controlled dust-treated plants better than lower volumes tested and the use of three adjuvants  (ammonium sulfate, nonionic surfactant, and organosilicone surfactant) were helpful but only partially overcame the adverse effect of dust on glyphosate. Methylated seed oil or petroleum oil adjuvants did not improve glyphosate control of dust-treated or untreated plants.

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