A Master Gardener friend recently contacted me asking if I knew an expert who could talk to her garden group about growing tomatoes . Noting that problems with fungi were “particularly worrisome,” she threw down the gauntlet: “Need to learn more about it and how to control it.”
When I suggested that the high heat and humidity in the District of Columbia provide an ideal environment for fungi, and that selecting disease resistant tomatoes might be a better strategy than trying to keep fungi out of the garden, she got downright testy. My advice was “not helpful,” she said. “I have grown tomatoes for over 35 years and it is a bit more complicated than just looking for the resistant ones. The fungi has (sic) been a concern with local gardeners here and I am looking for a person who has technical info about controlling the spread and what are the options.”
I guess this falls into the category of no good deed going unpunished. But it got me thinking–or rather wondering whether I am simply crazy for thinking that trying to grow tomatoes organically and avoiding fungi are not concepts that work easily together in the same sentence. And am I missing something when I can look at the varieties of tomato plants in my own garden and observe that some of them clearly are more resistant to disease than others?
First, I should say that I have very little experience with pests and diseases in my garden. I rotate my crops every year. I use lots of compost I make myself. I do very little watering. But I don’t know that I’ve ever seen a tomato plant–either in my own garden or elsewhere–that did not experience wilt or some other common ailment at some point in its life. Fungi are everywhere, and they are the most common destroyer of plants.
I looked online and found a report from the University of Maryland stating that commercial tomato growers in the state commonly spray fungicides on their plants. But they also practice crop rotation and selection of resistant varieties.
Standard practices besides rotation are to avoid planting tomatoes where other nightshade cousins such as potatoes, peppers and eggplants were growing previously. Keep tomato plants well separated to promote good air circulation. Try to keep the foliage dry–don’t water from the top down. Don’t touch tomato plants when they’re wet. Wash hands and tools after handling tomatoes. Remove and trash (don’t compost) diseased tomato plant material. Disinfect tomato cages before reusing.
I admit, I intially was not happy about the way my Mortgage Lifter tomatoes started to wilt early in my garden this year. They are a bit unsightly, but boy are the tomatoes good–big, juicy and full of flavor. Integrated Pest Management practices would have me consider whether I can live with the wilt as long as my Mortgage Lifters are producing such great fruit. More and more I’m inclined to think the wilt is tolerable. Our Cherokee Purples and Dr. Carolyns, both heirloom varieties like Mortgage Lifter, have suffered very little. On the other hand, our Striped Zebra plants hardly grew or produced at all–they were completely overcome with wilt. (I see a battle coming, as my wife really likes Striped Zebra tomatoes and can’t believe there isn’t a way to grow them successfully here.) My Big Boy plant, meanwhile, which is a modern variety, not an heirloom, has survived the whole season without wilt, but the fruit isn’t nearly as good at the Mortgage Lifter or Cherokee Purple.
So how do you feel about this, fellow gardeners? Is fungus something we need to control, or are there ways we can co-exist with microbes and still grow great tomatoes?
Note: Southern Exposure Seed Exchange, one of my favorite seed providers located not too far from here outside Charlottesville, Virginia, sells a more disease resitant strain of Mortgage Lifter. The fruit is said to be a little smaller, but equally as delicious.