Worldwide distribution. On potato, tomato and relatives, and weeds. An important disease.
Irregular patches of rot on leaves; white cottony growth with spores on undersides. Leaves yellow, shrivel and fall. Tubers rot. Spread in wind and rain and in “seed”.
Cultural control: certified seed; remove volunteers; drainage; 2-3-year crop rotation; spacing to aid air movement; drip irrigation; limit amount of N; early tolerant varieties, avoid cull piles; collect and burn trash after harvest.
Chemical control: chlorothalonil, mancozeb, or copper; alternate with, e.g., dimethomorth, metalaxyl, cymoxanil, or strobilurins. Phosphorus acid either alone or with chlorothalonil.
AUTHOR Grahame Jackson Information from CABI (2015) Phytophthora infestans (Phytophthora blight) Crop Protection Compendium. (https://www.cabi.org/cpc/datasheet/40970); and information (and Diagram) from Schumann G, D’Arcy CJ (2000) Late blight of potato and tomato. The Plant Health Instructor. DOI: 10.1094/PHI-I-2000-0724-01. Updated 2005. Photo 2 Howard F. Schwartz, Colorado State University, Bugwood.org. Photo 3 Agriculture Research Service, United States Department of Agriculture.
Produced with support from the Australian Centre for International Agricultural Research under project PC/2010/090: Strengthening integrated crop management research in the Pacific Islands in support of sustainable intensification of high-value crop production, implemented by the University of Queensland and the Secretariat of the Pacific Community.