Symptoms: A persistent fungal disease, verticillium wilt is found on many fruits and garden vegetables, especially tomatoes, potatoes, peppers and eggplant. Fruit trees and woody ornamentals subject to infection include pear, cherry, plum and roses.
Verticillium wilt attacks the “circulatory system” of host plants and interferes with the upward flow of water. Symptoms are indicated by new growth dying-off in summer months. Typically, leaves at the ends of branches turn yellow, wilt and fall before the entire limb or branch dies. Often one branch or one side of the plant is affected.
Verticillium wilt overwinters in garden debris and fallen fruit, and lives in the soil. The disease is transmitted and moved during cultivation, transplanting, or by flowing water and soil moisture. Verticillium is also transmitted from plant to plant by grafting and budding.
Note: Verticillium fungi can survive for 10 or more years in the soil without a host plant.
Control: There is no cure for this soil borne disease. Sulfur applications applied weekly once the symptoms appear may have some effect, but prevention practices will be more effective in the long run. Choose resistant varieties when available. Remove stricken growth and sterilize clippers between cuts. It is best to remove the entire plant and solarize the soil* before planting again in the same location. Crop rotation will have limited success, as so many crops are susceptible to the disease fungi. Avoid high nitrogen fertilizers.
* To solarize your soil, you must leave a clear plastic tarp on the soil surface for 4-6 weeks during the hottest part of the year. Soil solarization will reduce or eliminate many soil inhabiting pests, including nematodes, fungi, insects, weeds and weed seeds.