Cotton (Gossypium hirsutum L.) Injury, Growth, and Yield Following Low-Dose Flumioxazin Postemergence Applications

Abstract

The effects of postemergence (POST) herbicides off-target movement on cotton has been evaluated, but no data is available evaluating simulated off-target movement of residual herbicides. Therefore, low-dose POST applications of flumioxazin were evaluated in cotton at the cotyledon, two- and four-leaf growth stages. Rates evaluated were 12.5, 25, and 50% of the labeled use rate of 72 g ai ha-1. Necrosis, cotton height and width reduction was observed. Cotyledon cotton was injured 69 to 86%, 80 to 91%, and 84 to 97% following the 12.5, 25, and 50% flumioxazin rates, respectively, 3 through 42 DAT. Injury of two-leaf cotton increased from 3 to 14 DAT for all flumioxazin rates with maximum injury of 40, 47, and 58% following the 12.5, 25, and 50% rates, respectively, 14 DAT, but injury decreased following the 14 DAT evaluation. Injury of four-leaf cotton was 46 to 58% 3 DAT and decreased over time regardless of rate. At 42 DAT, two- and four-leaf cotton was injured 14 to 33% and increased with flumioxazin rate. Cotton height and width averaged 40, 80, 86% of the nontreated following the cotyledon, two-, and four-leaf application timings, respectively, 42 DAT. In addition, height was more influenced by flumioxazin rate than cotton width. Yields were 24, 52, and 62% of the nontreated following the cotyledon, two-, and four-leaf applications timings, respectively. In addition, yields following the 12.5, 25, and 50% rates were 53, 45, and 40% of the nontreated. Low-doses of flumioxazin reduced revenue $1,172 to $2,344 ha-1 for lint and $212 to 423 ha-1 for cotton seed. Low-doses of flumioxazin POST can have negative effects on cotton growth and yield and could cause severe economic loss for a cotton producer.

HPPD inhibitor-susceptible soybean growth, yield, and economic return following isoxaflutole and mesotrione applied postemergence

“…However, our findings are in agreement with those of Young et al (2003), who reported that soybean injury decreased as soybean growth stage increased following mesotrione postemergence. Similarly, soybean and cotton injury following low-dose flumioxazin decreased as growth stage increased (Stephenson et al 2019a(Stephenson et al , 2019b.…”

“…At all locations, treatments were applied with a CO 2 -pressurized backpack sprayer in a constant carrier volume of 140 L ha −1 . Others have simulated off-target movement of herbicides utilizing constant carrier volume (Al-Khatib et al 2003;Bailey and Kapusta 1993;Ellis et al 2003;Sperry et al 2019;Stephenson et al 2019aStephenson et al , 2019bSteppig et al 2018). At Alexandria, all treatments were applied at 190 kPa using four flat-fan 11002 nozzles (AIXR TeeJet®, TeeJet Technologies Southeast, P.O.…”

“…Visible chlorosis, necrosis, and height reduction were accounted for in the visible injury rating, which is consistent with Frans et al (1986), who described using visible discoloration and stunting to determine visible injury. Soybean heights were recorded at 14, 28, and 42 DAT by measuring 10 randomly selected plants in each plot from the soil to the apical terminal of each plant (Rana et al 2014;Sperry et al 2019;Stephenson et al 2019aStephenson et al , 2019b. Soybean heights were collected to provide a quantitative measurement of potential height reduction caused by the treatments.…”

“…Off-target movement of pesticides ranges from 1% to 8% and 20% to 35% for ground and aerial applications, respectively (Maybank et al 1978;Wolf et al 1992). Others have evaluated simulated herbicide off-target movement on corn (Zea mays L.), cotton (Gossypium hirsutum L.), grain sorghum [Sorghum bicolor (L.) Moench], rice (Oryza sativa L.), and soybean (Al-Khatib et al 2003;Bailey and Kapusta 1993;Ellis et al , 2003Matocha and Jones 2015;Sperry et al 2019;Stephenson et al 2019aStephenson et al , 2019bSteppig et al 2018).…”