HPIPM:Potato Foliar Fungicides

Author: Gary D. Franc

Properly timed and properly applied foliar fungicides delay the onset of disease and will also slow the rate at which foliar disease develops. Foliar fungicides are an important component of an integrated disease management program. Thorough coverage, the proper rate and correct timing are necessary for successful disease management.

Late Blight

The causal organism, Phytophthora infestans, overwinters in infected potato tubers. The main source for initial inoculum is infected seed potatoes and infected potatoes discarded in cull piles. Fungicides are an important component of a comprehensive late blight management program. An application schedule based on environmental parameters (accumulated severity values) can effectively be used to time foliar fungicide applications. Under most situations, thorough coverage of fungicide must be in place prior to secondary disease spread. The most effective programs will start before disease appears and when products are applied at their maximum labeled rate. Management of foliar disease may indirectly protect tubers from infection and reduce storage loss.

Early Blight

Early blight, caused by Alternaria solani, can cause serious losses in the field as well as in storage. Most general protectant fungicides used for late blight will also control early blight. Fungicides applied prior to the appearance of the first early blight lesions will provide no additional control. Proper irrigation and fertility will reduce losses due to early blight by reducing plant stress. Foliar disease severity is often not related to the degree of tuber decay. Minimize tuber bruising injury during harvest and provide optimal conditions for wound healing, in order to reduce tuber decay.

Due to constantly changing labels, laws and regulations, the sponsors of this web site assume no liability for the suggested use of any chemicals noted in the management section. Contact your local pest management personnel for current information on labeled pesticides that can be used for the intended plant disease, insect pest or weed.