Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2004
Publication Date: 7/1/2004
Citation: Price, A.J., Wilcut, J.W., Cranmer, J.R. 2004. Physiological behavior of root-absorbed flumioxazin in peanut, ivyleaf morningglory, and sicklepod. Weed Science. 52:718-724
Interpretive Summary: Peanut growers typically utilize preemergence herbicides that are applied after peanut planting and before peanut emergence. Valor (flumioxazin) is a recently registered preemregence herbicide. Widespread injury following Valor application was observed throughout the southeast. Research was conducted to determine why peanut was injured and why two weeds common in the Southeast U.S. exhibit differential tolerance to Valor preemergence. Results show that differential tolerance to Valor was due to differential absorption, translocation, and metabolism exhibited by peanut, ivyleaf morningglory, and sicklepod. These studies also suggest that Valor injury on seedling peanut is likely caused by rainfall occurring after Valor application and peanut emergence, if rainfall does not occur prior to peanut emergence. Thus, peanut growers need to anticipate receiving rainfall or applying overhead irrigation on Valor PRE treated soil within approximately 6 d of application to reduce probability of peanut injury.
Technical Abstract: Previous research has shown that flumioxazin has the potential to cause peanut injury. In response to this concern, laboratory experiments were conducted to investigate the influence of temperature on germination of flumioxazin-treated peanut seed. Also, greenhouse experiments investigated the influence of six different irrigation intervals on peanut emergence and injury after a soil-applied preemergence (PRE) application of flumioxazin. Laboratory experiments utilizing 14C-flumioxazin were also conducted to investigate differential tolerances exhibited by peanut, ivyleaf morningglory, and sicklepod to flumioxazin. Flumioxazin treatments containing either water dispersible granular (WDG) or wettable powder (WP) formulation at 1.4 'mol/L did not influence germination compared to non-treated peanut across all temperature regimes. Peanut treated with both formulations of flumioxazin PRE and receiving irrigation at emergence, and 2 and 4 d after emergence were injured between 40 and 60%, while peanut treated at 8 and 12 d after emergence were injured between 25 and 15%, respectively. Total 14C absorbed by ivyleaf mornigglory was 57% of applied while sicklepod absorbed 46%, 72 hours after treatment (HAT). Peanut absorbed ' 74% of applied 14C 72 HAT. The majority of absorbed 14C remained in roots of sicklepod, ivyleaf morningglory, and peanut at all harvest times. Ivyleaf morningglory contained 41% of the parent herbicide 72 HAT while sicklepod and peanut contained only 24 and 11% parent compound, respectively. Regression slopes indicated slower metabolism by ivyleaf morningglory compared to sicklepod and peanut.