Field studies were conducted in 1999 and 2000 at Marianna and Gainesville, FL, to evaluate the response of three runner-type peanut cultivars, ‘Georgia Green’, ‘C-99R’, and ‘MDR-98’, to flumioxazin applied preemergence at 0, 71, 105, and 211 g/ha in a weed-free environment. Peanut exhibited excellent tolerance to flumioxazin, regardless of flumioxazin rate or peanut cultivar, at Gainesville in 1999 and both locations in 2000. In 1999, at Marianna, flumioxazin caused early-season stunting and season-long reduction in peanut canopy width. Peanut response was independent of cultivar and did not exceed 25%, with an increase in stunting with higher flumioxazin rates. Peanut stunting was associated with cool and extremely wet growing conditions during the first 2 mo after planting in 1999 at Marianna. Peanut yield and grade parameters, in both years, were not affected by flumioxazin treatment.

Nomenclature: Flumioxazin; peanut, Arachis hypogaea L. ‘Georgia Green’, ‘C-99R’, ‘MDR-98’.

Additional index words: Cultivar, extra large kernels, grade analysis, other kernels, sound mature kernels, sound splits, total sound mature kernels, yield.

Abbreviations: DAP, days after planting; ELK, extra large kernels; OK, other kernels; PPI, preplant incorporated; PPO, protoporphyrinogen oxidase; PRE, preemergence; SMK, sound mature kernels; SS, sound splits; TSMK, total sound mature kernels.