Organizing Committee


Poster Presentations


Poster Presentations


Efficacy of foliar fungicides for Asian soybean rust disease management and yield enhancement in Alabama

Presenter: Dennis P. Delaney(2)

Other authors and affiliations: Katheryn S. Lawrence(1), Edward J. Sikora(1), Gary W. Lawrence(3), Mary A. Delaney(1), Malcomb D. Pegues(4). (1)Auburn University, Department of Entomology & Plant Pathology, Auburn, AL 36849, U.S.A.; (2)Auburn University, Department of Agronomy & Soils, Auburn, AL 36849, U.S.A.; (3)Mississippi State University, Department of Entomology & Plant Pathology, Mississippi State, MS 39762, U.S.A.; (4)Auburn University, Gulf Coast Research Extension Center, AAES, Fairhope, AL 36532, U.S.A.

Field evaluations of fungicides for control of Asian soybean rust (Phakopsora pachyrhizi) were conducted at the Auburn University, Gulf Coast REC at Fairhope, AL. Three foliar fungicide tests evaluating 24 fungicide combinations were established in 2006 utilizing RCB designs with four replications each. Fungicides were applied at the R1 plant growth stage and 21 days later with a Lee Spider high-clearance sprayer equipped with Turbodrop TDXL 10002 flat fan nozzles on 15-in. centers at 60 psi with 24 gpa. Soybean foliar diseases were evaluated by rating severity of each disease in the plot at the R6 to R7 growth stage. Soybean rust leaf symptoms were first observed in the untreated control plots in mid-September when the soybeans were at the R6 full-seed growth stage. Two weeks later, rust severity had increased in all plots but was significantly more severe (P ≤ 0.05) in the untreated control as compared with all fungicide treatments. Rust severity was less than 2.55% leaf coverage in all of the fungicide treatments at R6 but increased to 2535% in some treatments 2 weeks later. Disease signs were rated in the lower canopy but were also observed in the upper canopy of the control plots. Soybean yields were increased (P ≤ 0.05) by all fungicide treatments as compared with the control. The average increase in yield over all fungicide treatments was 13.3 bu/acre or 19% as compared with the control. Available data from the 2007 trials will also be discussed.

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