Verticillium wilt
Class: Fungi
Common Name
Verticillium wilt
Scientific name
Primarily caused by two fungi: Verticillium dahliae and Verticillium albo-atrum
Potential Hosts
Tomato, potato, pepper, eggplant, cucumber, melon, pumpkin, watermelon, broccoli, cabbage, cauliflower, celery, garlic, kohlrabi, lettuce, onion, peas, radish, spinach, and turnip
Who am I?
Verticillium wilt is a fatal disease that affects a wide range of vegetable crops. The pathogen survives in the soil as dormant microsclerotia (small survival bodies) and favors cool to moderate weather conditions. Plant debris can serve as an overwintering site for these fungi. Both Verticillium species cause nearly the same symptoms.
Initial symptoms of Verticillium wilt include the sudden yellowing of foliage that typically appears on one side of leaves. Generally, older leaves are affected first. The symptoms progress up the plant; eventually the entire plant becomes affected and dies.
Peeling away the outer layers of affected stems or branches may reveal a brown streak in the vascular tissue. Infected plants may exhibit wilting during the hottest part of the day, but can recover at night.
Control measures
Unfortunately, plants infected with Verticillium cannot be cured and will eventually die. Therefore, prevention is a key factor.
Cultural
Crop rotation: Do not grow crops that are highly susceptible to Verticillium wilt in the same field year after year. Rotate susceptible crops with less susceptible crops such as corn.
Resistant varieties: There are varieties resistant to verticillium wilt. For instance, some tomato varieties are marked with the letter “V” after the variety name.
Sanitation: Eliminate potential sources of verticillium in your field:
*Keep weeds under control; they can often serve as a reservoir for this fungi.
*Discard old debris from infected plants. Don't bury or compost debris.
*Decontaminate tools and equipment that came into contact with infected plants with a bleach solution in order to prevent the spread of the fungi.
Soil disinfection: Solar disinfection of the soil (solarization or pasteurization) can be implemented in sunny areas. This involves covering prepared and moistened soil with a polyethylene film 35–50 μm thick and keeping it in place for at least 1 month during a sunny period of the year. This has the potential to reduce the presence of the fungi in the top layers of soil. It is common for solar disinfection to be accompanied by fumigants such as metam-sodium.
Conventional (chemical)
The following are fungicides used in one or more parts of the world: benomyl\carbendazim and propamocarb.
Important Note
Verticillium wilt might be confused with fusarium wilt. The two diseases have similar symptoms. Therefore, here are tips to distinguish between fusarium and verticillium:
*Verticillium wilt mainly affects plants when they approach maturity, whereas fusarium wilt can affect plants at any growth stage.
Cut the stem open lengthwise and see how far up the plant the dark vascular discoloration extends; *In verticillium wilt, discoloration does not occur as far up the plant as it does in fusarium wilt.
Wilting is the main symptom of verticillium, and appears similar to bacterial canker which may cause confusion. Although, in bacterial canker, a yellow to white ooze can be seen when the stem is cut at the base of the plant,
Caution and careful notice should be taken when using any plant protection products (insecticides, fungicides, and herbicides). It is the grower’s sole responsibility to keep track of the legal uses and permissions with respect to the laws in their country and destination markets. Always read the instructions written on labels, and in a case of contradiction, work in accordance to the product label. Keep in mind that information written on the label usually applies to local markets. Pest control products intended for organic farming are generally considered to be less effective in comparison to conventional products. When dealing with organic, biologic, and to some extent a small number of conventional chemical products, a complete eradication of a pest or disease will often require several iterations of a specific treatment or combination of treatments.