Late Blight of Potato and Tomato (PP301)

Figure 1. 1A. Cool, foggy weather that occurs during winter tomato production in Florida is ideal for late blight disease development. B. Tomato leaves heavily symptomatic for late blight lesions. C. Late blight lesions on fruit and leaves. D. Tomato leaves on water agar to induce sporulation of Phytophthora infestans, which can be observed as the white, fluffy structures on the leaf surface. Both potato and tomato are susceptible to late blight, an aggressive disease capable of rapidly destroying entire fields. The disease is distributed worldwide and occurs wherever tomatoes or potatoes are grown and conditions favor disease development. This 4-page fact sheet was written by Ryan Donahoo and Pamela Roberts, and published by the UF Department of Plant Pathology, December 2012.