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Title: Absorption and fate of aminocyclopyrachlor in tall fescue.

item PARKER, E - Auburn University
item WEHTJE, G - Auburn University
item MCELROY, J - Auburn University
item Price, Andrew
item MCCULLOUGH, P - Auburn University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/15/2013
Publication Date: 2/15/2013
Citation: Parker, E.T., Wehtje, G.R., Mcelroy, J.S., Price, A.J., Mccullough, P. 2013. Absorption and fate of aminocyclopyrachlor in tall fescue. Southern Weed Science Society. CDROM.

Interpretive Summary:

Technical Abstract: Aminocyclopyrachlor (AMCP) is a hormone disrupting herbicide that exhibits selective broadleaf weed control in tolerant graminaceous species. Some questions have risen over the ability of AMCP applied at labeled rates to translocate to and escape from plant roots into the soil, therefore prolonging the life of the herbicide in the soil. Studies were performed to evaluate AMCP foliar absorption and translocation using radiolabeled AMCP in tall fescue. Bioassay studies were also performed to determine whether AMCP root exudation exists in tall fescue. Absorption and translocation did not vary significantly from 24 Hours After Treatment (HAT) to 192 HAT. AMCP absorption was greatest at 192 HAT but did not exceed 8.9%. Translocation throughout the study was minimal and ranged from 0.9% of applied AMCP at 24 HAT to 5.3% moving out of the treated area at 192 HAT. Absorption and translocation data indicate that AMCP is minimally translocated upward toward the leaf tip when applied to the foliage, likely through the xylem. These results indicate that AMCP is only slightly absorbed into tall fescue foliage and translocation amounts were negligible. The root exudation study indicated that dicamba treatments resulted in significantly more damage to bioassay species than did AMCP treatments. Dicamba treated pots exhibited 56, 64, and 76% damage to bioassay species at 1, 2, and 3 WAT respectively. AMCP treatments resulted in 14% damage to bioassay species across all time intervals. Based on these data, AMCP does exude through tall fescue roots after foliar treatment into the surrounding environment but is minor and less than dicamba.