There is verticillium wilt in the front corner of my yard. An affected tree...
There is verticillium wilt in the front corner of my yard. An affected tree was removed and now I want to re-landscape the area. In the process of amending the soil, I'll end up removing some of the existing soil. How should I dispose of the removed soil that I know contains the verticillium wilt fungus?
Ramsey County Minnesota
Thank you for the question. The answer depends on how much soil you think will be discarded. If it's just a small amount it's possible that your trash hauler will let you dispose of it in plastic bags but you should check with them first. Do not add it to your home compost pile due to the risk of spreading the disease. The same is true for municipal compost sites. Most won't accept soil in any case.
If the area is larger, there are some techniques to reduce the amount of verticillium in the soil. I have never done this nor have I known anyone who has but I'll include links for your information and you can decide for yourself. The two techniques are called soil solarization which involves using a transparent film and the heat of the sun to kill the organisms, and anaerobic soil disinfection which involves creating anaerobic soil conditions by incorporating easily decomposable organic materials (wheat bran, molasses, rice straw, and rice bran, for example) into soil that is irrigated and subsequently covered with plastic film. The advantage of anaerobic soil disinfestation over soil solarization is that the method does not require high solar radiation so it can be applied to cloudy areas or periods of low sunlight, thus a growing season is not lost. These processes are labor intensive and may not be suitable for homeowners. Read here to learn about soil solarization http://www.ext.colostate.edu/pubs/crops/00505.html Read here to learn about anaerobic soil disinfection http://www.extension.org/pages/64951/soilborne-disease-management-in-organic-vegetable-productioc Interesting options for treating soil borne infestations n#.VVn7wblVhB
Another option if you have lots of soil is to check into hiring a licensed pesticide applicator to fumigate the soil.
And of course, only plant verticillium wilt resistant plants back in this location because no matter what you do, some of the organisms will live indefinitely in the soil.
Thank you for contacting Extension.
Thank you for your response to my question about disposing of soil that contains the fungus verticillium wilt. The arborist from the tree company originally diagnosed the problem. How can I determine whether and/or how much of the fungus is left after treating the soil? Is there a soil test? The area involved is about 15 square feet.
You will have verticillium wilt fungus in your soil for an indeterminate number of years that's why it's important to use resistant plants. A routine soil test checks soil fertility but not for pathogens so I suggest you call the University of Minnesota Plant Pathology lab and check with them. They do test for verticillium wilt on plants and maybe they would on soil but I don't know. There is a cost for this service and their prices are listed http://pdc.umn.edu/