Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Tomato (Lycopersicon esculentum) -- Wilts (Fusarium wilt, Verticillium wilt)
 
Cause: Fusarium oxysporum f. sp. lycopersici, Verticillium albo-atrum, or V. dahliae, fungi that live in soil and cause wilt symptoms. Verticillium spp. survive in infected debris up to 8 years and are favored by cool weather (68 to 75oF). F. oxysporum f. sp. lycopersici is favored by warmer weather (84oF) and can survive several years in soil. Fusarium wilt is favored by high phosphorus, ammonium nitrogen, or micronutrient levels. Verticillium spp. infect a wide range of weed and crop plants. These wilt fungi can be spread by infested equipment, transplants, and windborne or waterborne infested soil.
Symptoms: Symptoms are similar for both fungi, so the diseases cannot be distinguished based on symptoms alone. Lower leaves yellow, mostly on one side. Plants wilt during the hot part of the day but recover in the evening. Eventually the leaves remain wilted, shrivel, turn brown, and die. The vascular system discolors. Growth is retarded, and yields are low.

Fusarium wilt.
 
Cultural control:

  1. Use resistant cultivars. They are marked with a V (for Verticillium resistance) and/or F (for Fusarium resistance). Several VF lines are available from seed companies.
  2. Home gardeners should remove and destroy all affected plant tissue, including roots.
  3. Rotating out of tomatoes 4 to 6 years may reduce losses from either disease, but success is not assured because the host range is so wide.
Content edited by: Cynthia M. Ocamb on January 1, 2009
 
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