Verticillium Wilt

Verticillium dahliae can infect eggplant plants at any growth stage. Symptoms include yellowing and drooping of leaves on a few branches or on the entire plant. The edges of the leaves roll inward on infected plants, and foliar wilting ensues. The foliage of severely infected plants turns brown and dry. Plants infected early in the season can be severely stunted with small leaves that turn yellow-green. Subsequently, the dried leaves and shriveled fruits remain attached to plants that die. Brown discoloration of the vascular tissue is visible when the roots and lower stem of a wilted plant are cut longitudinally. Root rots also cause similar foliar symptoms; however, root rots cause extensive browning and rotting of the root cortex, while the roots of V. dahliae-infected eggplant plants show no external discoloration or decay.

Verticillium wilt, caused by Verticillium dahliae, is a soilborne fungus that colonizes the vascular tissues of plants. Verticillium dahliae has a broad host range, causing vascular discoloration and wilt of many economically important crops. Microsclerotia produced by V. dahliae may survive under field conditions for up to 14 years in the absence of a host. The microsclerotia germinate in the vicinity of host roots and cause infection. Verticillium wilt is favored by cool air and soil temperatures.

Soil fumigation of V. dahliae using chloropicrin (most effective) or metam sodium is effective. Because of the longevity of microsclerotia and the broad host range of V. dahliae, crop rotation is usually not a feasible option for control of Verticillium wilt in many crops. However, rotations with broccoli, corn, wheat, barley, sorghum or safflower for a period of at least 2 years (the longer the rotation, the better) can reduce inoculum. These crops are not hosts for the Verticillium pathogen, and populations of the pathogen will decline in fields where host plants are not present. In any case, do not replant eggplants in the field for a minimum of 3 years. There are no known varieties with resistance.

While solarizationis very effective against Verticillium, its use is limited because the process is done during the middle of summer, which interrupts the growing cycle of the eggplants. Beds that are solarized are actually being prepared for planting the following year. For more information see Soil Solarization for Gardens and Landscapes or UC Publication 21377 Soil Solarization: A Nonpesticidal Method for Controlling Diseases, Nematodes, and Weeds. (PDF)