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Title: SILVERLEAF POVERTYWEED BIOLOGY AND CONTROL IN DRYLAND CROPS

Author
item Henry, William
item HELM, A - COLO STATE UNIV EXTENSION
item WESTRA, P - COLO STATE UNIV FACULTY

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 1/2/2004
Publication Date: 1/2/2004
Citation: Henry, W.B., Helm, A., Westra, P. 2004. Silverleaf povertyweed biology and control in dryland crops. Agronomy Abstracts. Presented at the Western Society of Weed Science Annual Meeting. March 2004. Colorado Springs, Colo.

Interpretive Summary:

Technical Abstract: Silverleaf povertyweed, Ambrosia grayi, is a deep-rooted perennial that is increasingly becoming a problem in dryland agricultural systems in Eastern Colorado. This weed is also called lagoon weed because of its propensity to grow in low lying areas that often have saturated soils. As tillage decreases and the reliance on burndown application of herbicides increases, weeds with an extensive root system that can withstand typical herbicide application rates have an advantage and can develop into troublesome species. Studies were conducted at three locations, two near Holyoke, CO and one near Planter, CO. Clopyralid applied at two rates 0.25 and 0.5lb ai/A and picloram also at 0.25 and 0.375 lb ai/A were not effective treatments providing at best 31% control at 8 weeks after application, WAA. 2, 4-D and banvel treatments containing at least 1.5 lb ai/A and 1 lb ai/A, respectively, controlled silverleaf povertyweed 95% or greater at 8 WAA. This weed was sensitive to formulation of glyphosate with Engame and Roundup Ultramax both at 1 lb ea/A providing 33 and 84% control, respectively. Population counts this spring will determine the effectiveness of tankmix partners in the 2, 4-D and banvel treatments.