Verticillium wilt is caused by two different species of a soilborne fungus: Verticillium albo-atrum and Verticillium dahliae. Initial symptoms of Verticillium wilt include yellowing of the lower leaves, wilting, stunted growth, and v-shaped lesions that extend inward from the margin of the leaf. Brown, necrotic tissue begins to develop within the lesions as the disease progresses. Symptoms of wilting may only occur late in the season or once the disease is advanced. Because the pathogen affects the vascular tissue (water and nutrient conducting vessels). Plants may wilt in the afternoon when they are actively transpiring and appear to “recover” in the morning, only to wilt again. Lower leaves will begin to die and fall off, eventually leading to plant death. Similar to Fusarium wilt, longitudinal light brown to cream colored streaks can be seen underneath the outside stem tissue and are most prominent at the base of the plant. Vascular streaking can also be observed in the leaves, and this is a characteristic symptom of Verticillium wilt. Plants that do persist in spite of infection will have greatly reduced fruit yields.

Look alike diseases: Lack of moisture or symptoms of other wilt diseases including bacterial wilt, Fusarium wilt, and southern blight may be confused with symptoms of Verticillium wilt. However, V-shaped leaf lesions are distinctive of Verticillium wilt.

Once plants are infected with Verticillium wilt it is impossible to eradicate disease with treatment. Preventative measures to inhibit disease introduction are the most effective options.

• Select resistant varieties. Planting resistant varieties will help inhibit severe symptoms of disease. See the Southeastern US Vegetable Crop Handbook for a list of varieties with resistance. However, widespread deployment of resistant varieties has led to the development of pathogen races that can overcome resistance. If a variety that is resistant to Verticillium wilt has been deployed and symptoms are still observed, then non-race 1 strains are likely to be present for which there is no known resistance at this time.
• Incorporate crop rotations. Rotating to non-host plants at 4-5 year intervals is advised for disease control. The wide host range of the Verticillium wilt pathogen may limit possible rotational crops, but non-susceptible grass and wheat species are recommended.
• Discard infected plant material. The fungus can survive for extended periods of time within plant tissue. The immediate removal of infected plants is necessary to discourage the persistence of the pathogen, if possible.
• Soil solarization. Heating the top six inches of soil to high temperatures for an extended period of time can kill the fungus and reduce the number of infected plants. However, this practice is difficult to implement in the southeastern US because it must be done during summer months. Frequent rainfall and cloudy days make it difficult to maintain the high temperatures needed to be successful.
• Sanitize equipment and tools. Tractors and other equipment that travel between fields should be cleaned frequently to avoid transport of infected soil. Rinse pots and tools thoroughly with water and treat for at least 30 seconds in a 10% bleach solution or 70% alcohol.
• Grow early-maturing varieties. Quickly-maturing crops are likely to begin producing fruit before they completely succumb to disease. This can improve fruit yield in fields with a history of Verticillium wilt.
• Control weeds. Asymptomatic weedy plants can spread disease to susceptible crops. Fields should be frequently and diligently maintained.
• Use mulch from resistant trees. Mulch used from susceptible trees may introduce Verticillium wilt. Conifers, beech, hickory, white oak, and poplar trees are resistant to this disease and a safer source of mulch.