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:
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.