Verticillium Wilt – What to Grow

Verticillium Wilt is a soil-borne fungus that affects a wide variety of plants, from vegetables and perennials to trees and shrubs. The fungus damages and kills plants by ‘plugging up’ its vascular tissue, preventing water and nutrients from flowing throughout the plant. The first signs of damage are usually seen midsummer when we have our first week without rainfall and individual branches suddenly die- this is called ‘flagging’. This is caused by the fungus preventing much-needed water from reaching the tips of these branches.

It is an incurable and often terminal disease in plants. There is no cure once a plant is infected. You may be able to keep the plant alive by regularly watering, but every time the plant is stressed more of its parts will die.

The good news is that Verticillium Wilt is usually a localized disease. I have seen trees of the same species growing only 20 feet from one another where one is infected and the other is perfectly healthy. When it comes to management, there are two strategies:

If your landscape is free of Verticillium:

• DO NOT use “free” mulch or wood chips in your garden beds as this can introduce the fungus from the infected chips.
• DO NOT allow infected leaves to collect on-site. Leaf mulches are great as long as they come from healthy trees.

If your landscape has Verticillium:

• DO sanitize your pruning equipment between cuts on infected plants with 70% alcohol.
• DO keep infected plants healthy through proper watering and mulching
• DO plant resistant species.
• DO NOT plant susceptible species in areas you know have it.
• DO NOT transplant your plants elsewhere in your landscape or give them to friends.
• DO NOT keep infected plant parts on site- burn them or dispose of them in the garbage.

See the below table for information on plants that are resistant and those that are susceptible to the disease. This list does not currently include vegetable/food crops.