Tips For Verticillium Wilt Treatment in Vegetable Garden

Photo by Howard F. Schwartz, Colorado State University, Bugwood.org

Your plants started to wilt. Are the fungi causing this symptoms - or is it something else? Let's see how verticillium wilt attacks the plants. When you recognize the signs of the infection you can act. When you understand how the fungus spreads, you know how to control it.

Apply the following tips for verticillium wilt treatment in your vegetable garden. Discover which tomato varieties are resistant to this disease. Let's start with the definition to understand your enemy.

What is verticillium wilt?

It's a fungal disease attacking from the soil. There are two different species of verticillium wilts: V. albo-atrum spp.and V. dahliae spp. They come in various strains of different virulence.

This disease can attack over 300 species of plants. Vegetables from Solanaceae family, like tomatoes, potatoes, peppers or squash are typical victims. Naturally growing trees like maple can harbour the disease as well. You may discover the symptoms on the shrub, strawberry, sunflower and other flora in your garden.

These fungi infect the plant through the naturally occuring lesions in the roots. Then the disease spreads along the infected plant's vascular system - the pipes inside the stem transporting the nutrients and water.

This problem occurs usually during July and August. However, it can appear at any time in the season. This fungus is a hardy pathogen which survives winter and remains hidden in the soil for over 10 years.

How does verticillium wilt spread?

• It can spread from plant to plant when roots touch each other or penetrate contaminated soil.
• Gardening tools can transport the disease to the clear area of your garden.
• The new plant rooted in the contaminated soil can be a Trojan Horse. Looking still healthy it introduces verticillium wilt into your veggie patch.
• Seeds obtained from the infected plants may introduce disease as well. These you can fix with fungicide treatment before planting in your garden.
• Fungi can travel in the irrigation ditches for over a mile.

Symptoms of verticillium wilt

• Verticillium wilt releases poisonous substances that weaken the plant. To fight the infection, compromised plant attempts to block the infected vessels. However, this results in wilting - the process which gave a name to this disease.
• You can observe stunted growth.
• Small, yellow leaves may get brown or curl. Sometimes only the areas between the veins on the leaf seem affected.
• Leaves fall off leading to the sunburned fruits due to the lack of foliage protection.
• Fruits grow small and less numerous. Sometimes they stop growing at all and drop off before maturing.
• The vascular tissue appears streaked or discoloured. This effect is most noticeable when you peel off the bark or skin. When you cut through the ill branch, it may look as the dark ring.

Photo by Howard F. Schwartz, Colorado State University, Bugwood.org

Sometimes only one site of the plant seems to suffer, depending on the location of the infection source. The symptoms may last for years on the perennials without doing a lot of damages. Or the attack quickly kills the plant. In severe cases the branches, shoots or the whole plants wilt and die within days.

Is this verticillium wilt?

Other problems cause similar symptoms as well. Consider the possibility of the damage caused by herbicides, fertilisation mistakes, mechanical injuries of the plant, influence of the weather conditions, especially drought or overwatering plants.

Fusarium wilt infection looks almost identical. However, it prefers hot weather and dislikes the frost. On the other hand, verticillium wilt overwinters well and thrives in a cool weather.

Laboratory tests can help to confirm the diagnosis. They are rarely necessary as both diseases respond to the similar treatment. Consider testing only if you are not sure if the fungi cause issues in your vegetable garden.

Verticillium wilt treatment

Chemical fungicides fail to help because they can't reach the fungus lurking in the soil and inside your plants. So how can you treat this disease? You face the two choices.

• Remove and destroy infected plants before verticillium wilt spreads through the whole patch.
• Let them remain in the garden till the end of the season (or longer if you deal with perennials) if the symptoms are mild.

The fungus enjoys wet soil so make sure you irrigate correctly and avoid overwatering. The strong plants resist any disease better and verticillium wilt is no exception. Apply fertilizers containing less nitrogen and more potassium to improve plant's resistance.

Since the fruits can fall off from infected tomato plants, collect them and allow to mature elsewhere.

Verticillium wilt control and management

This fungal disease can survive over ten years in the soil and is difficult to remove. You could fumigate the soil for verticillium wilt, but the procedure is quite expensive, especially when performed on large area. Following tips will help you manage the disease and minimalize the impact of verticillium wilt in your garden.

• Destroy the infected plant remains when the gardening season is over. Burn them or throw away - never compost infected stuff!
• Solarize your soil in the empty areas of your garden during the middle of the summer . How? Irrigate the soil till it's wet. Then spread transparent plastic foil over the ground. Dig the edges into the soil or secure them with stones. Finally, let the soil restfor 6 weeks.
• Till the soil during the fall.
• Use the crop rotation so that there's a few years break before you grow plants susceptible to verticillium wilt in the same spot again. It doesn't kill the fungi completely, but allows you to control the disease.
• Grow the susceptible vegetables in the containers, using the clean soil for planting. It's even possible to grow indeterminate tomatoes in containers. This way you can avoid the infection when growing heirloom vegetables.
• Cultivate vegetable varieties resistant to the verticillium wilt if you don't mind planting hybrids.

These last two tips enable you to succeed when the pathogens lurk in the soil

7 best verticillium wilt resistant tomato varieties

When shopping for verticillium wilt resistant tomatoes, look for the "V" sign on the seed packet. Below you can find the list of 7 best hybrid determinate and indeterminate tomato varieties resistant to fusarium and verticillium wilts and nematodes. Links lead to Amazon.com where you can buy tomato seeds or seedlings.

• Beefmaster VFN - Determinate hybrid with large beefsteak meaty fruits, good for canning, drying and fresh
• Celebrity VFNT - Determinate hybrid, medium fruit good for canning, drying and fresh
• Pik Red VFN - Determinate hybrid variety with medium fruits, best fresh
• Better boy VFN - Indeterminate hybrid with large, juicy fruits, juicy, eat fresh
• Big Beef VFNT - Indeterminate hybrid, medium round fruits, All-American Selections winner
• Lemon Boy VFN - Indeterminate hybrid with medium yellow fruits, specific taste, eat fresh
• Sweet Chelsea VFNT - Indeterminate cherry tomato hybrid with small fruits, best fresh