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Poster: Biology & Disease Mgmt: Integrated Pest Mgmt


Managing Potato Pink Rot Using Chemical and Non-Chemical Strategies
X. ZHANG (1), J. Hao (1), H. Jiang (1), N. Marangoni (1), X. Zhang (1) (1) University of Maine, U.S.A.

Pink rot (Phytophthora erythroseptica) is a widespread disease on potatoes (Solanum tuberosum). Controlling pink rot becomes a challenge owing to the fast development of a fungicide-resistant P. erythroseptica population. To determine effective strategies for pink rot control, field trials were conducted in 2014 and 2015 using fungicides or crop rotation. Pink-rot-susceptible seed tubers (cv. ‘Russet Norkotah’) were used. Phytophthora erythroseptica inoculum was distributed in-furrow at planting prior to soil treatments. In fungicide trials, chemical and biological products were applied in-furrow at planting or through soil drenching after plant emergence. The crop rotation trial was conducted with “rotation crop-potato” sequences. Tuber yield was measured and disease severity was rated based on a “0 (healthy tuber) to 5 (>50% rot area)” scale at harvest. Fluopicolide, mefenoxam–oxathiapiprolin combinations, and fluopicolide/oxathiapiprolin plus Bacillus combinations significantly reduced pink rot. None of the tested biocontrol agents significantly reduced pink rot alone. Mefenoxam was effective when there was no mefenoxam-resistant population of P. erythroseptica. Oats, clover, and barley underseeded with ryegrass lowered pink rot severity levels, although it was not statistically significant. Soil microbial communities in rotation plots are being investigated using next generation sequencing technology.