Eggplant Verticillium Wilt Control : Treating Verticillium Wilt In Eggplants
Verticillium wilt is a common pathogen among many varieties of plants. It has over 300 host families, spanning edibles, ornamentals, and evergreens. Eggplant verticillium wilt is devastating to the crop. Plants in the nightshade family, such as tomatoes, eggplant, and potatoes are all adversely affected. The symptoms mimic those of several other diseases, so it is important to know them completely and make an accurate diagnosis.
Symptoms for Eggplants with Verticillium Wilt
Verticillium wilt in eggplants is caused by a fungus that lives and overwinters in the soil for years. It not only occurs in nightshades but also cucurbits, evergreens, herbs, flowering ornamentals, and even trees. The disease attacks vascular tissue, disrupting the movement of nutrients and water. Over time, the plant will become stunted, fail to produce useable fruit, and eventually die. The plant material is still very contagious and has to be destroyed rather than go into the compost heap.
Yellowing, wilting eggplants are the first sign that something is wrong. Young plants become stunted with leaves that are too small and yellowish-green. The disease can splash up on leaves, which means those closest to the soil line are generally first to show signs of infection. Leaves fade at the edges, roll inward, and eventually turn brown and dry. The disease will progress to other leaves and stems, and finally the root system.
The fungus produces a toxin that gums up the vascular system, preventing the movement of water. Unlike fusarium rot, yellows, and bacterial wilt, verticillium prefers to linger in temperate regions where the soil is cool. Vascular streaking in leaves and stems can help differentiate eggplant verticillium wilt from other common diseases.
Preventing Verticillium Wilt in Eggplants
Annual cleanup is an effective way of reducing the possibility of re-infection. Old plant material is a host for the pathogen and should be destroyed. Crop rotation may be beneficial, especially with nightshade hosts. Keep weeds out of the area, since some are also hosts to the disease.
As always, prevent contaminating fields by washing tires and cleaning tools and other equipment. Solarization of a soil area may also control the fungus.
If at all possible, get hold of resistant varieties. These will have a “V” marked on the seed packet. The cultivars ‘Classic’ and ‘Epic’ seem to have some good resistance to the disease.
Treatments for Wilting Eggplants
Unfortunately, there are no easy-to-use chemicals to spray on your garden bed or field. After testing to ensure that the disease really is caused by verticillium, licensed applicators are required to handle the recommended chemicals. A soil fumigant is the most common application.
The fungicide, benomyl, has been shown to be useful as a transplant dip to reduce contamination but it is only useful initially and cannot protect roots after the plant has gone into contaminated soil.
Eggplants with verticillium wilt are difficult to treat. Better still are preventative measures such as resistant varieties, sanitation practices, sterilized soil, and removal of host plants.
How to Manage Pests
Pathogen: Verticillium dahliae
(Reviewed 4/10 , updated 4/10, pesticides updated 5/16 )
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.
Comments on the Disease
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 Verticilliumpathogen, 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.
|Common name||Amount per acre**||REI‡||PHI‡|
|(Example trade name)||(hours)||(days)|
|When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide's properties, efficacy, application timing, and information relating to resistance management, honey bees (PDF) , and environmental impact. Not all registered pesticides are listed. Always read the label of the product being used.|
|A.||1,3-DICHLOROPROPENE* / CHLOROPICRIN*|
|(InLine)||Label rates||See label||NA|
|COMMENTS: Multi-purpose liquid fumigant for the preplant treatment of soil against plant-parasitic nematodes, symphylans and certain soil-borne pathogens using drip irrigation systems only. Use of a plastic mulch or tarp seal is mandatory for all applications of this product.|
|(Vapam)||Label rates||See label||NA|
|COMMENTS: For use in sprinkler, drip, or furrow-irrigated fields. Apply with enough water to penetrate 18 to 24 inches and treat at least 50% of planting bed width. Follow recommended waiting period on label before planting to avoid injury to plants.|
|**||See label for dilution rates.|
|‡||Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing.|
|*||Permit required from county agricultural commissioner for purchase or use.|