Previous research has shown that flumioxazin has the potential to cause peanut injury. In response to this concern, laboratory and greenhouse experiments were conducted to investigate the influence of temperature on germination of flumioxazin-treated peanut seed and the effect of interval between flumioxazin application and irrigation on peanut emergence and injury. Laboratory experiments using 14C-flumioxazin were also conducted to investigate differential tolerance exhibited by peanut, ivyleaf morningglory, and sicklepod to flumioxazin. Flumioxazin treatments containing either water-dispersible granular or wettable powder formulation at 1.4 μmol L−1 did not influence germination compared with nontreated peanut across all temperature regimes (15 to 40 C). Peanut treated with either formulations of flumioxazin preemergence and receiving irrigation at emergence and 2 and 4 d after emergence were injured between 40 and 60%. 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 whereas sicklepod absorbed 46%, 72 h 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 whereas sicklepod and peanut contained only 24 and 11% parent compound, respectively. Regression slopes indicated slower flumioxazin metabolism by ivyleaf morningglory (a susceptible species) compared with sicklepod and peanut (tolerant species).

Studies were conducted to evaluate absorption, translocation, and metabolism of 14C-CGA 362622 when foliar applied to cotton, peanut, jimsonweed, and sicklepod. Differential metabolism is the basis for tolerance in cotton and jimsonweed. In addition, cotton absorbs less herbicide compared with the other three species, thus aiding in tolerance. Only jimsonweed translocated appreciable herbicide (25%) out of treated leaves and acropetally to the meristematic tissue where the herbicide was quickly metabolized. No plant species translocated over 2% of applied radioactivity below the treated leaves. Most of the metabolites formed by the four species were more polar than CGA 362622 and averaged 51, 48, 30, and 25% of the radioactivity detected in the treated leaves of cotton, jimsonweed, peanut, and sicklepod, respectively. The half-life of CGA 362622 was estimated to be 0.8, 1.9, 4, and 6 d in treated leaves of cotton, jimsonweed, sicklepod, and peanut, respectively.