Skip to main content
ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #250054
Title: Effect of compensatory growth on Palmer amaranth response to glyphosate.

Author
item SOSNOSKIE, L.M. - University Of Georgia
item CULPEPPER, A.S. - University Of Georgia
item Webster, Theodore

Submitted to: Proceedings of Southern Weed Science Society
Publication Type: Abstract Only
Publication Acceptance Date: 2/11/2010
Publication Date: 6/1/2010
Citation: Sosnoskie, L., Culpepper, A., Webster, T.M. 2010. Effect of compensatory growth on Palmer amaranth response to glyphosate. Proceedings of Southern Weed Science Society. 63:33.

Interpretive Summary:

Technical Abstract: Incomplete weed control can occur after herbicide applications. Death of one or many shoot meristems could remove apical dominance, leading to compensatory growth from once dormant lateral buds. Palmer amaranth (PA) dieback and regrowth in response to POST herbicides has been observed. The objective of this study was to determine if glyphosate sensitivity differed between intact plants and those undergoing mechanically stimulated compensatory growth for both glyphosate-susceptible (GLY-S) and –resistant (GLY-R) PA biotypes. GLY-S Plants with compensatory growth (grown to 10-15 cm, cut back, and regrown to 10-15 cm) were more sensitive to glyphosate than intact plants. The GR50 (rate resulting in 50% Fresh Weight reduction) for the intact plants was >300% that of regrown plants, while the I50 (rate resulting in 50% injury) for the intact plants was 111% that of regrown plants. Intact and regrown GLY-R plants did not differ with respect to glyphosate sensitivity. PA is a problem in cotton production in the SE US. PA dieback and regrowth in response to incomplete herbicide control has been observed in the field. Plants that persist following herbicide applications may compete with the crop and reproduce, thereby reducing yields and replenishing the soil seedbank, respectively. Future trials will evaluate GLY-S and GLY-R PA susceptibility to other common POST applied herbicides in cotton production. This will allow us to determine how subsequent weed control measures following herbicide failure may be impacted by compensatory growth.