The Battle against Late Blight, From the Irish Potato Famine to the New Millennium
While hard to believe, the Late Blight pathogen that caused the Irish potato famine in the 1840s and 1850s and caused the starvation deaths and forced migration of hundreds of thousands across Europe, is still a major concern in food production worldwide. The fungus-like organism, Phytophthora infestans, is aggressive and can cause disease that can rapidly destroy whole fields of potatoes and tomatoes. This centuries old threat is still with us and causes major concerns for potato growers in Wisconsin each year!
The pathogen can be spread quickly over whole areas by wind movement of its spores from infected source plants. These are either brought into the state as already infected tomato transplants or seed potatoes or can develop locally from un-harvested tubers or crop waste that survive freezing. Because it can spread so rapidly under cool moist conditions, Late blight is considered a ‘community disease’ that can affect both commercial growers and home gardeners alike. Crop fields must therefore be monitored early to detect symptoms and potential disease sources. Growers ensure that seed is disease-free to prevent the introduction of the pathogen into the fields. They control potato volunteers and nightshade weeds that may be infected in and around production fields. And, by WI state law, growers, homeowners and garden centers are required to destroy all disease sources by May 20th before the start of the growing season. (more…)