Large‐scale evaluation of physical drift and volatility of 2,4‐D choline in cotton: a four‐year field study

Abstract

BACKGROUND: Cotton with resistance to 2,4-D choline, glufosinate and glyphosate allows over-the-top use of these herbicides for postemergence weed control. Nontransgenic cotton is highly responsive to low rates of 2,4-D, causing concern among farmers when the herbicide is applied near the crop. Injury to nearby cotton following application of 2,4-D choline is sometimes blamed on volatilization of the herbicide.RESULTS: A large-scale experiment was conducted in 2018-2021 to better understand causes of damage to nearby sensitive cotton following an application of 2,4-D choline plus glufosinate-ammonium. The herbicides were applied to 0.4 ha in the center of a 4-ha non-Enlist cotton field. At 30 min after application, air samplers were established in the treated center and outside the treated area in cardinal directions. The 72-h cumulative air concentration of 2,4-D in the swath ranged from 3.3 to 7.1 ng m −3 , and most volatile residues (5.0-25.5 ng m −3 ) were detected in samplers established in the downwind direction directly adjacent to the treated field. Cotton plants in three downwind transects that were covered for 30 min after application were not damaged by 2,4-D, whereas noncovered plants along the downwind transects were injured. No cotton injury occurred outside the treated area, except in the downwind direction during application even though wind direction changed after application. CONCLUSION: 2,4-D choline volatilizes, but findings show that the volatilization is not sufficient to damage cotton in the neighboring area following applications, pointing to the importance of applicators understanding wind direction/shift during the application along with proximity of sensitive crops in the downwind direction.

Use of plant growth regulators to reduce 2-methyl-4-chlorophenoxy acetic acid-Na (MPCA-Na) damage in cotton (Gossypium hirsutum)

“…Most herbicides have injurious effects on crop growth, causing leaves to shrink, inhibiting plant height, and causing flowers and fruit to drop, all of which cause serious reductions in crop yield [31,32]. After exposure, crops tend to regulate their physiological and metabolic functions in order to convert herbicides into harmless compounds [33].…”

Residue of Pesticides in Fruits, Vegetables, and Their Management in Ethiopia

“…Te procedure is reliant on the pesticide's vapor pressure, and low vapor pressure pesticides stay on the surface for a longer period of time than those with high vapor pressure, which tend to volatilize quickly into the air [42]. Te rate of volatilization is also infuenced by external variables, including temperature and wind speed, and the rate of pesticide evaporation increases with increasing speed and temperature [43].…”

Toxicity Assessment of 36 Herbicides to Green Algae: Effects of Mode of Action and Chemical Family

“…As the mist containing 2,4-D butylate travels, moisture in the droplets evaporates rapidly, leaving behind a gaseous herbicide that can be carried further by the wind. It has been observed that under wind force scales of 3 or 4, the drift can extend up to nearly 100 m, and under wind force scales of 6 or 7, it can reach distances of 1500 to 2000 m [29]. Additionally, 2,4-D butylate may volatilize and drift downwind for a second time within 12 days of initial application [29].…”