Professor & Extension Specialist University of Idaho Kimberly, Idaho
Adopting potato cultivar-specific disease management programs for field and storage can minimize losses and inputs. Cultivar disease susceptibility can influence the effectiveness and usefulness of a fungicide-based program. The objective of a 2-year study was to evaluate various fungicides programs in the field and storage to assess fungicide needs based upon cultivar disease susceptibility. Replicated field and storage trials were conducted on eight russet-type cultivars (Russet (R) Burbank, R. Ranger, R. Norkotah, Umatilla R., Clearwater R., Teton R. and Dakota R.) to compare the performance of a standard fungicide program against foliar, soil-borne, and storage diseases. Diseases/disorders evaluated included Fusarium dry rot, Rhizoctonia canker, powdery scab, early blight/brown spot, white mold, pink rot, Pythium leak, potato mop top virus (PMTV), blackspot and shatter bruise, along with plant productivity indicators such as emergence, stem number, and yield. Fungicide programs varied depending on the disease being evaluated. Significant interactions between cultivar and fungicide program were observed for in-season Fusarium dry rot incidence, Rhizoctonia canker severity, early blight/brown spot severity, emergence, stem number, plant vigor and total yield. Post-harvest interactions were observed for the incidence of Pythium leak, pink rot, Fusarium dry rot, and blackspot bruise. In general, Alturas was more susceptible for white mold and PMTV symptoms, R. Burbank for Fusarium seed decay, Rhizoctonia, and powdery scab on roots, Clearwater R. for pink rot, leak, and Fusarium in storage, Dakota R. for powdery scab on roots and PMTV symptoms, R. Norkotah for early blight, white mold, and pink rot, Ranger R. for Fusarium seed decay, Rhizoctonia, white mold, and dry rot in storage, Teton R. for powdery scab on roots, early blight, and leak, and Umatilla R. for Fusarium seed decay, powdery scab on roots, and leak. Varieties with relatively high susceptibility will require concentrated management efforts to counter these diseases.
