![]() They thrive at soil temperatures between 15 and 23 ☌ and higher water content than is optimal for crop growth. We comply with the Federal Trade Commission 1998 Children’s Online Privacy Protection Act (COPPA).Phytophthora species are very destructive organisms belonging to the Oomycetes and are therefore strictly speaking not fungi. The 4-H Name and Emblem have special protections from Congress, protected by code 18 USC 707. Reference to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned. This information is for educational purposes only. Quentin Tyler, Director, MSU Extension, East Lansing, MI 48824. Issued in furtherance of MSU Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, gender identity, religion, age, height, weight, disability, political beliefs, sexual orientation, marital status, family status or veteran status. MSU is an affirmative-action, equal-opportunity employer, committed to achieving excellence through a diverse workforce and inclusive culture that encourages all people to reach their full potential. Hausbeck’s work is funded in part by MSU’s AgBioResearch. Please see “ Tomato Late Blight Fungicide Recommendations 2014” or Michigan State University Extension Bulletin 312, “ 2014 Insect, Disease and Nematode Control for Commercial Vegetables,” for a listing of fungicides that are registered.ĭr. In addition to the fungicides commonly used for early blight, Septoria and anthracnose, there are several highly effective fungicide sprays that are late blight-specific that can be used to protect tomato plants from this disease. Many commonly-grown tomato varieties are susceptible to late blight. Cool nights, moderately warm days, and weather that keep foliage or fruit wet for several hours are ideal for late blight development.Ĭontrol measures include eliminating all potato and tomato cull piles in the vicinity of tomato plantings and destroying volunteer potato plants that grow from overwintered tubers. Right, Tomato fruits infected with late blight.īetween cropping seasons, the late blight pathogen survives on volunteer and abandoned potato and tomato plants in fields, cull piles and homeowner gardens. Left, Late blight lesion on a tomato stem. During wet and humid conditions, white threads (mycelium) can be seen on the fruit. The blighting on fruit from late blight appears as dark, greasy areas that enlarge rapidly, encompassing the entire fruit. The other commonly occurring tomato diseases do not cause a rot of the green fruit. ![]() Late blight affects green and ripened tomato fruits (Photo 3). Blackened lesions on the stems also occur and are unique to late blight disease (Photo 2). Lesions on leaves often appear dark and oily with production of spores occurring on the undersides of the leaves, resulting in a purplish appearance, especially when conditions are wet and humid (Photo 1). Late blight symptoms include blighting on all aboveground parts of the tomato plant. Tomato growers practicing integrated pest management use fungicides to protect against early blight, Septoria and anthracnose, and many of these fungicides also provide adequate protection against late blight. The late blight spores from this infected potato field can infect nearby tomatoes. This disease was recently reported in Michigan from a commercial potato field in Allegan County. When the weather is favorable, as it has been in 2014, late blight can be especially troublesome. Late blight ( Phytophthora infestans) is a disease that most commonly affects potatoes, but can infect tomatoes in some years.
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