Hello,

Thank you for using the Ask Extension service. I have some follow-up questions.

How did you determine that the disease was anthracnose? You had the flattened circles with growth starting in the middle of the ripe tomato fruit? See some photos in this article. Do you have any photos that you can send me of both the fruit and the tomato plants growing in the garden?

The soaker hose was a good idea, to get the water where it needs to be, at the base of the plant. How did you trellis the tomatoes? Did you do any pruning of the tomato plants, and space them well for good air circulation?

Would you say that the plants are in full sun? Full sun is very important for good vegetable production, especially tomatoes.

It sounds like you do already have in place a few of the “cultural control” methods that would be recommended (soaker hose, trellising, mulching, planning crop rotation). Also, dispose of diseased plant parts and fruit and remove them from your garden area. Do not put them in the compost (if you have one) if that compost will go back on the vegetable garden.

To your main question, I do not know of a product to treat anthracnose in the soil. There are some fungicide products that can be applied as a soil drench to manage root rot pathogens, like fusarium or verticillium, but these would be recommended for commercial growers. The soil is a complex matrix, with beneficial and pathogenic microbes in it, and it is not easy or desirable to kill off most of the microbes there. I also asked our most senior MSUE Commercial Vegetable Educator and he would not recommend a soil-applied fungicide.

If you decide that a fungicide is necessary to protect the upper parts of the plants this season, look for a product where the label mentions that it can be used for the specific crop you would like to protect (tomatoes), and against the specific diseases/pathogens that you think you have in your garden. Please see the resources I listed below for fungicide options. Make sure to READ AND FOLLOW all label instructions when using a pesticide product. The label is the law. Monitor your plants throughout the growing season for signs of disease and try to catch it as early as possible.

I also recommend looking for disease-resistant tomato varieties. It seems like there are almost no tomato varieties resistant to anthracnose (I found 1 variety on a Cornell list of many tomato varieties), however having tomato plants with some resistance to other diseases will help keep your plants healthy overall.

Cornell has nice tables of disease-resistant vegetable varieties. They separate the tomatoes into cherry, grape, heirloom, plum, slicer. The couple tip sheets I am going to list for resources on early blight and late blight on tomato also have a few variety suggestions each. You can also look for notes about disease resistance or tolerance when browsing transplant varieties in the garden center. Plus, check the roots, soil line, and upper parts of the transplants in the store for potential disease symptoms before purchasing plants!

Some resources:

A Pocket Guide to Common Diseases in the Urban Garden from MSU

Homeowner’s Guide to Fungicides from the University of Kentucky, updated 2019

Home Garden Fungicides from the University of Wisconsin-Madison, revised 2012

Lists of Disease-resistant tomato varieties from Cornell University – click on the details links in each category to see the tables that include details about which diseases the varieties have tolerance to

Tomato Disease Identification Key from Cornell University – Vegetable MD Online

Tomato diseases, insects, and disorders webinar from MSU Extension

Organic Management of Early Blight on Tomato from MSU Extension

Organic Management of Late Blight on Tomato from MSU Extension

Also consider going to our MSU Extension Gardening in Michigan website and checking out our resources on growing vegetables, including our Smart Gardening vegetable tip sheets.

Regards,

Irene