|Prostko, Eric - UNIVERSITY OF GEORGIA|
Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 4, 2002
Publication Date: February 11, 2003
Citation: Johnson, W.C., Prostko, E.P. 2003. Phytotoxicity of delayed applications of flumioxazin on peanut [abstract]. Weed Science Society of America Abstracts. 43:80. Technical Abstract: Weed free trials were conducted in 2001 and 2002 at two sites in Georgia to investigate the phytotoxicity of intentionally late applications of flumioxazin on 'C99R'peanut. The experimental design was a split with four replications. Main plots were times of flumioxazin application; 0, 2, 4, 6, 8, and 10 days after planting (DAP). Sub-plots were flumioxazin rates; nontreated, 71, and 105 g ai/ha. Soil at the Attapulgus, GA site was a Lucy loamy sand; 88% sand, 8% silt, 4% clay, and 0.4% organic matter. Soil at the Tifton, GA site was a Tifton loam sand; 88% sand, 6% silt, 6% clay, and 0.2% organic matter. Peanut were seeded shallow, 3.2 cm deep, creating worse-case conditions for phytotoxicity. Immediately after seeding, peanut were irrigated. Data collected were visual estimations of peanut injury (three ratings), canopy width (three measurements), final stand, and yield. Peanut seed were sprouting at 6 DAP, causing the soil surface to crack. Peanut seedlings were beginning to emerge and epicotyl visible at 8 DAP. Peanut were fully emerged with considerable foliage present 10 DAP. Flumioxazin applied to peanut 6, 8, and 10 DAP significantly injured peanut and reduced canopy width. Phytotoxicity was consistently greater with flumioxazin at 105 g/ha compared to 71 g/ha. However, stand was not reduced by any of the applications or rates. Peanut growth generally recovered by mid-season. Peanut yields were not consistently affected by either flumioxazin times of application or rate. These preliminary results show that the optimum time of application is from immediately after planting to three days after planting, but within that range the earlier applications are suggested. The highest recommended flumioxazin rate, 105 g/ha, is not overly phytotoxic when applied within the recommended range of timings.