Seed treatment application-timing options for control of fusarium decay and sprout rot of cut seedpieces

Abstract

The efficacy of application timings of a commercially formulated mixture of fludioxonil plus mancozeb (Maxim MZ) applied prior to planting for the control of seedpiece decay and rotting of sprouts, caused by the dry rot pathogenFusarium sambucinum, was evaluated over two years. Cut potato seedpieces were inoculated with a virulent strain ofF. sambucinum and either treated with the fungicide mixture or not. Treatment applications were made 10, 5 or 2 days prior to planting. Seedpiece and sprout health were evaluatedin vitro and agronomic impacts were evaluatedin vivo in field experiments. Overall, thein vitro experiments indicated that inoculation withF. sambucinum did not have an effect on the mean number of sprouts per seedpiece but did affect the incidence of rotting sprouts and seedpiece decay. However, treatment of seedpieces with the fungicide mixture 10, 5 or 2 days before planting significantly reduced the percentage of diseased sprouts per seed-piece and seedpiece decay. Inoculated seedpieces treated with the fungicide mixture produced similar numbers of healthy sprouts as did the non-inoculated seedpieces. The experiment, conducted in 2003, showed that final plant stand, RAUEPC and RAUCCC were similar for non-inoculated seedpieces and inoculated fungicide-treated seedpieces. Overall, there were no significant differences among treatment timings, and these results suggest that applying a fungicide seed treatment up to 10 days prior to planting can provide effective control of both Fusarium seedpiece decay and sprout rot.