Integrated Potato Black Scurf Management Principle IPM Practice Tuberborne inoculum contributes towards disease development in western Washington Use seed tubers free of black scurf, and seed fungicides like Maxim which have efficacy against Rhizoctonia Rhizoctonia is sometimes subject to antagonism by soil micro-organisms Avoid planting seed tubers with black scurf in soil that has been recently fumigated (beneficial effects of the antagonists may be temporarily eliminated) Severe stem cankers can lead to scurfy, scaly, deformed tubers Promote conditions that favor rapid emergence such as avoidance of cold, wet soil; practice shallow planting and gradual hilling; rotate out of potato for 3 years to reduce the soilborne inoculum that may contact plant stems Sclerotia of the fungus form as the potato periderm matures Avoid vine destruction practices that kill vines rapidly, such as burning and cutting For additional information: http://pnwhandbooks.orst.edu/guide1998/disease.cfm?RecordID=904.00000

 

Integrated Potato Late Blight Management Principle IPM Practice Contaminated seed pieces may lead to transmission of the fungus from the seed piece to the emerging sprout Use seed piece fungicides with efficacy against P. infestans. Foliar fungicides need to be used preventively when weather conditions are favorable or when disease is first noted in the area; they need to reapplied as plants grow or rain washes them off leaf surfaces Dimethomorph, cymoxanil, and propamocarb hydrochloride were first registered as Section 18 fungicides for late blight control in WA in 1996.  They are more effective than other registered protectant fungicides in western Washington IF disease onset is early (late May to June). Populations of P. infestans in western Washington remain insensitive to metalaxyl Do not use Ridomil products without protectant fungicides Cultivars repond differently Russet Norkotah, Hilite Russet, Red LaSoda, White Rose, and Shepody are highly susceptible Potatoes planted late in the growing season (June) in western Washington may be exposed to higher levels of inoculum during the season than potatoes planted in April or May Plant potatoes as early during the growing season as possible Cull piles, tare dirt from storages, volunteer potatoes and other Solanaceous hosts are potential sources of inoculum for P. infestans in western Washington Use appropriate sanitation practices; follow proper guidelines regarding cull pile disposal and feeding to livestock For additional information: http:// www.bcc.orst.edu/lateblight/ http://pnwhandbooks.orst.edu/guide1998/disease.cfm?RecordID=890.00000

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