Submitted to: National Soybean Rust Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 7/29/2006
Publication Date: 8/2/2006
Citation: Mueller, T.A., Morel, W., Levy, C., Miles, M.R., Hartman, G.L. 2006. Evaluation of Fungicides and Fungicide Timing for the Control of Phakopsora pachyrhizi in Paraguay and Zimbabwe. National Soybean Rust Symposium. Available at: http://plantmanagementnetwork.org/infocenter/topic/soybeanrust/2006/posters/52.asp.
Technical Abstract: Timing of fungicide applications is a critical component in managing soybean rust and if used effectively, may reduce the number of applications needed for economic benefit. The objectives of these experiments were to evaluate the effects of different timings of fungicide applications on soybean rust severity and yields. Trials were conducted in three locations in Paraguay in growers’ fields (Bella Vista, Pirapo, and Capitán Meza) and in Harare, Zimbabwe at the Rattray Arnold Research Station. Varieties of soybean were representative of the region they were planted in. Treatments in each field included applications with: triazole (Folicur), strobilurin (Headline), or triazole-strobilurin combinations (Quilt or Headline + Folicur) at either (i) growth stage (GS) R1, (ii) GS R3, (iii) GS R5, (iv) GS R1 and R3, (v) GS R3 and R5, (vi) GS R1, R3, and R5, or (vii) not sprayed. For all locations the nontreated control had higher soybean rust severity and lower yield than most of the treatments with fungicides. In Zimbabwe, the yields for 15 of the 23 treatments were significantly greater than the nontreated control. In Paraguay, Bella Vista had 6, Pirapo had 19, and Capitan Meza had 17 of 23 treatments that had significantly greater yields than the nontreated control. In general, when fungicides were applied soybean rust was less severe and the yields were higher with a tendency to be greater as the number of fungicides applications increased.