Tips For Verticillium Wilt Treatment in Vegetable Garden

Verticillium wilt in vegetable garden picture
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 signs of an infection, you can act to help veggies. When you understand how the fungus spreads, you'll know how to control it.

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

What is verticillium wilt?

It's a fungal disease, which attacks 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 its 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 plants through naturally occuring lesions in their roots. Then, the disease spreads along the infected plant's vascular system - the pipes inside the stem transporting the nutrients and water.

The problem occurs usually during July and August. However, it can appear at any time in the season. This fungus is a hardy pathogen, which easily survives winter. It 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 the contaminated soil.
  • Gardening tools can transport the disease to the previously clear area of your garden.
  • Any new plant, rooted in the contaminated soil, can be the Trojan Horse. Looking, as if it were still healthy, it introduces verticillium wilt into your veggie patch.
  • Seeds obtained from the infected plants may introduce disease as well. However, you can fix them with fungicide treatment, before planting any in your garden.
  • Fungi can travel in 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 off its infected vessels. However, this results in wilting - the process which gave a name to this disease.
  • You can observe thestunted 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 like the dark ring.

Verticillium wilt symptoms discoloration picture
Photo by Howard F. Schwartz, Colorado State University, Bugwood.org

Occasionally, only one side of the plant seems to suffer, depending on the location of an infection source. The symptoms may last for years on the perennials, without doing a lot of damages. Or the attack may quickly kill 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 a damage caused by herbicides, fertilisation mistakes, mechanical injuries of the plant, influence of the weather conditions, especially drought or overwatering plants.

A 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 with confirming the diagnosis. They are rarely necessary, as both diseases respond to a similar treatment. Consider testing only, when you are unsure, if the fungi cause issues in your vegetable garden.

Verticillium wilt treatment

Chemical fungicides fail to help, because they can't reach the fungus, which lurks in the soil and inside your plants. So how can you treat this disease? You face 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 a wet soil, so make sure to irrigate correctly and avoid overwatering. Strong plants resist any disease better, and verticillium wilt is no exception. Apply fertilizers, which contain 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 the large area. Following tips will help you manage the disease and minimalize the impact of verticillium wilt in your garden.

  • Destroy any infected plant remains, when the gardening season is over. Burn them or throw away - never compost the infected stuff!
  • Solarize your soil in 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 susceptible vegetables in containers, using the clean soil for planting. It's even possible to grow indeterminate tomatoes in containers. This way, you can avoid an infection, when growing valuable heirloom vegetables.
  • Cultivate vegetable varieties, which are resistant to the verticillium wilt, if you don't mind planting hybrids.

These last two tips enable you to succeed, when 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. These 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, smooth and firm 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