Spray particle drift is a critical concern for herbicide applications. The largest focus for spray drift reduction practices has been placed on increasing spray droplet size. To more appropriately apply glyphosate and 2,4-D, research is needed to identify application parameters, specifically commonly-used nozzles and adjuvants, that can effectively increase droplet size and reduce drift potential of an application. The objectives of this research were to evaluate the influence of nozzle type and adjuvant on the droplet spectrum and particle drift deposits from an application of glyphosate and 2,4-D in a controlled-wind tunnel environment. The study was conducted in a completely randomized design with five replications in a 5 x 3 x 7 split-split-plot arrangement in space. Main plot, sub-plot, and sub-sub-plot consisted of five spray compositions (herbicide solution alone and in tank-mixtures with one of four different adjuvants), three nozzle types (XR11002, DG11002, and AIXR11002), and seven downwind distances from the nozzle (2, 3, 4, 5, 6, 7, and 12 m), respectively. Herbicide solution (HS) was composed of glyphosate and 2,4-D amine at rate of 1260 g ae ha-1 and 450 g ae ha-1, respectively. The carrier volume, pressure, and wind speed used were 94 L ha-1, 207 kPa, and 2.2 m s-1, respectively. Four adjuvants were individually added to the HS: non-ionic surfactant (NIS), drift reduction agent (DRA), modified vegetable oil (MVO), and silicone surfactant (SIL) at rates of 0.37, 0.31, 2.00, and 0.37% v v-1 of commercial products, respectively. In addition, a PTSA fluorescent tracer (1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt) was added to the solutions at 600 mg L-1 to be detected by fluorimetry. Round strings 2 mm diameter were used as drift collectors. The adjuvant MVO tank-mixture to the HS reduced the percentage of drift in comparison with the other adjuvants and HS alone for all three nozzles. Conversely, NIS adjuvant increased the drift when compared with HS for all three nozzles. The AIXR nozzle generated the lowest percentages of drift across solutions. Results suggest that MVO, SIL and NIS do not always work as drift reducing adjuvants, even though using an air-induction nozzle. Drift decreased exponentially as downwind distance increased across herbicide solutions.

Drift potential from glyphosate and 2,4-D applications as influenced by nozzle type and adjuvants

2019 Fall National Meeting

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