Verticillium wilt

Verticillium Wilt is a soil-borne fungal disease that affects a wide range of plants, including vegetables, fruits, ornamentals, and trees. The disease is caused by the fungi Verticillium dahliae and Verticillium albo-atrum.

Symptoms

The first symptoms of Verticillium Wilt often appear as yellowing and wilting of lower leaves, typically on one side of the plant or one branch of a tree. As the disease progresses, wilting and yellowing spread upward to the rest of the plant, often followed by browning and death of the foliage. In some cases, the plant may die back completely, only to regrow and then exhibit symptoms again.

Disease Cycle

The Verticillium fungi survive in the soil as microscopic, dark-colored structures called microsclerotia. These structures can survive for many years in the soil, even in the absence of a suitable host. When conditions are favorable, the microsclerotia germinate and infect the roots of susceptible plants. The fungi then grow up into the water-conducting vessels of the plant, producing toxins and blocking the flow of water and nutrients.

Management

Management of Verticillium Wilt involves a combination of cultural practices and, in some cases, the use of resistant varieties. Cultural practices include crop rotation, sanitation, and soil solarization. Crop rotation with non-host crops can help reduce the amount of Verticillium in the soil. Sanitation involves removing and destroying infected plant material to prevent the spread of the fungi. Soil solarization, a method of heating the soil by covering it with clear plastic, can kill the Verticillium fungi in the top few inches of soil.

Resistant Varieties

Some plant varieties are resistant to Verticillium Wilt. These varieties can be a good choice for areas where the disease is known to be present. However, resistance is not immunity, and even resistant varieties can become infected under high disease pressure.

See Also

• Fusarium Wilt
• Dutch Elm Disease
• Plant Pathology