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Early-Season Fungicide Programs for Peanut Disease Management

Y. C. Tsai and T. B. Brenneman

April 2018

Research

The efficacy of early-season prothioconazole applications on stem rot (Sclerotium rolfsii) epidemics of peanut (Arachis hypogaea) planted on different dates was evaluated to better understand stem rot development and obtain more consistent disease control. The industry standard cultivar (Georgia-06G) was planted on four different dates at about 2-week intervals starting 25 April of both 2012 and 2013. Plots were either not treated or treated with prothioconazole (0.16 kg a.i./ha) at 21 or 35 days after planting (DAP) applied in a 30-cm band. All plots received chlorothalonil (2.09 kg a.i./ha) for leaf spot control. The mean final stem rot incidence in nontreated plots for planting dates 1 to 4 were 32, 15, 13, and 9% in 2012 and 25, 13, 24, and 6% in 2013, respectively. Final incidence of stem rot in plots treated with prothioconazole followed a similar pattern, but disease incidence was reduced by an average of 36 and 46% in 2012 and 4 and 14% in 2013 for the 21 and 35 DAP applications, respectively. Pod yields in nontreated plots for planting dates 1 to 4 (chlorothalonil only) were 6,446, 6,578, 5,479, and 2,613 kg/ha in 2012 and 2,914, 6,456, 5,399, and 3,123 kg/ha in 2013, respectively. Prothioconazole-treated plots (at either 21 or 35 DAP) averaged 475 and 600 kg/ha higher yield than nontreated plots in 2012 and 2013, respectively, but the differences between these two timings were not significant (P > 0.10). Both 2012 and 2013 had relatively cooler spring temperatures and lower risk of early stem rot. The efficacy and yield increase from the early prothioconazole application may have been greater in a warmer spring.

doi:10.1094/PHP-05-17-0029-RS

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