Verticillium in cabbage: symptoms, causes, control

Verticillium in cabbage is a fungus that causes wilting and poor cabbage productivity. In this article from “WORLD OF PLANTS,” we discuss the most important methods of prevention and control.

Introduction to Verticillium in cabbage

• Scientific name: Verticillium spp
• Type of disease: fungal
• Verticillium wilt is a soil-borne fungal disease that affects many vegetable crops grown in Utah. It causes similar symptoms in its hosts.
• Verticillium wilt is caused by Verticillium dahliae or V. albo-atrum, both of which have been repeatedly diagnosed in Utah.
• Verticillium wilt is a soil-borne plant disease that attacks vascular tissue. It causes similar symptoms in its host and is difficult to control as it can survive in the soil for many years. Once a plant is infected, there is no treatment. Therefore, management should focus on preventive and cultural control practices.

Verticillium families in cabbage

. It is found in grapes, beans, peppers, hot peppers, eggplant, cabbage, apricots, peas, cucumbers, pumpkin, zucchini, tomatoes, potatoes, peas, chickpeas, cotton, garlic, corn, strawberries, and currants.

Cause of Verticillium disease in cabbage

Verticillium wilt is caused by the soil-borne fungus Verticillium dahliae, from the Dahlia species, which can grow on crop residues in the soil when there is no host present. It penetrates into the vascular tissue through roots or phloem wounds. When the fungus enters the roots of a plant or tree, it grows rapidly and blocks the transfer of water and nutrients from the roots to the shoot, causing wilting and decomposition of the plant tissues exposed to the air (leaves and trunks). The disease increases in warm, sunny weather conditions. In advanced stages of the disease, the fungus colonizes dead tissue, forming black structures, which can be seen with magnifying glasses. These structures allow the fungus to survive for many years in the soil.

Suitable environment for Verticillium in cabbage

Verticillium resting structures are able to survive freezing, thawing, thermal shock, dehydration and many other factors and are very strong and difficult to break down. The only factor it does not tolerate well is long periods of anaerobic conditions (such as during floods)

Life cycle of Verticillium in cabbage

The basic life cycle is similar in all Verticillium species although V. albo-atrum forms mycelium, V. dahliae forms microsclerotes, V. nubilum forms chlamydospores, and V. tricorpus forms all three. These resting structures can survive in the soil anywhere from 4 to 15 years depending on conditions such as temperature, water, and non-host crops.

When the roots of the host crop approach the dormant structures, root exudates (chemically diverse secretions) cause the filamentous fungal structures to germinate and grow toward the plant. Verticillium is a vascular disease and generally requires an opening in the root system to access the vascular structure of the plant. Verticillium produces conidia that are released into plant xylem tissue and colonize the plant in less than 24 hours. Verticillium is a cold weather disease that grows best in the 70-85°F range.

Symptoms of the disease include wilting, spotting or chlorosis of leaves and discoloration of vascular tissue in roots and lower stems. Wilting may occur on only one side of the plant.

Severely infected plants can quickly succumb and if not removed can release survival structures into the nearby environment where they will wait for the next host to repeat the cycle. The disease can spread from root to root and through infected seeds (up to 13 months). It rarely spreads above ground to healthy plants. Insects that feed through plant cuttings, such as leafhoppers and aphids, can transmit the disease from one plant to another.

The importance of Verticillium in cabbage

It has similar devastating effects on many of these plants. Generally, it reduces the quality and quantity of the crop by causing tissue discolouration, stunting, premature defoliation and death. Stock from infested nurseries may be restricted. Once a plant becomes infected, there is no way to treat it. Verticillium wilt is a particular concern in temperate and irrigated regions. Verticillium spp. It can occur naturally in forest soils, and when these soils are cultivated, the pathogen will infect the crop.

Symptoms of Verticillium in cabbage

. The disease appears in the form of yellowing of the plant leaves, and begins at the tips.

. But the main veins of the leaf remain green.

. Black lines also appear on the stems.

. The plant begins to wilt.

. Symptoms vary greatly between different crops. Yellowing and dryness often appear at the edges of older leaves on the plant. The plant's wilting extends to the rest of the tissue, giving the leaf a wilted appearance, often wilting on one side. This particular characteristic is called segmental yellowing or “unilateral” wilt. Black streaks develop on the trunk and extend from the base upward, leading to wilting of the trunk throughout the tree. The main symptoms are poor growth, premature leaf death, stunted growth, and death of entire branches. Discoloration of the wood tissue in the form of circular rings or slices may represent additional symptoms. Sometimes, upon close examination with a lens, small black dots can be seen on the affected tissue, or on adjacent healthy tissue.

Preventive measures for Verticillium in cabbage

• Use plant varieties that are resistant or susceptible to infection.
• Do not use mixed planting with sensitive crops that can spread the disease.
• Avoid fertilizers rich in nitrogen and excessive watering.
• Use plant tonics to strengthen plants against infection.
• Prune, remove and burn infected plant material.
• Clean all tools and equipment after handling infected plants.
• Do not work in the fields when the tree leaves are wet.
• Be careful not to damage the roots while working in the field.
• Expose the soil to solar radiation for a period of time (insolation).
• Remove and mix plant residues deep into the soil or burn them. Practice crop rotation with non-host plants.

Recommendations regarding pictures of Verticillium in cabbage

We recommend applying organic control in the early stages of the disease or when the crop is close to harvest. In the more advanced stages of the disease, please use chemical control.

It is not recommended to mix or use different products at the same time.

Organic control

The use of biofungicides containing the bacterium Streptomyces aydicus can break the disease cycle and help stop disease progression.

Chemical control

An integrated approach with preventive measures and biological treatments, if available, should always be relied upon. If trees are affected by the disease, it is difficult to get rid of them. Soil fumigation is considered a successful control method, but it is expensive. The success of the fumigation process depends on the chemical used for fumigation, the rate of use, and the environmental conditions during the fumigation process. Affected plant parts can also be treated

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References

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