Saturday, August 30, 2008

Fighting Nature

Maybe I shouldn't be so shocked, but I'm still surprised when I run across a gardener who insists on being able to control nature.

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.

5 comments:

el said...

I think one has to co-exist with "problems" like fungi. There are some things one can do with tomatoes (and you are surely doing them) to ensure a strong bunch of plants that have resistance to anything that comes along. Spacing them fairly far apart, trimming them mercilessly (especially lower and inner leaves), removing the top flowers are three things that ensure, in sequence, more air circulation, a strong root system and bigger fruit. Such practices are helpful with wilt and fungi.

FWIW, Green Zebras are always fairly pathetic plants with not much fruit set: it's what makes them so precious. I experimented this year with them. I trellised some in the greenhouse, I let one run free (untrellised, on the ground) in there, and I trellised a couple outside in different beds far apart from each other. The one that's running wild is doing fine, the ones outside are looking fairly pathetic this time of year, but the trellised ones inside the greenhouse are going bonkers. Still not as many fruits as other varieties though.

De in D.C. said...

There are always going to be up years and down years in the garden. Accepting this, and the knowledge that the next year will be different, is what keeps us planting those seeds each spring. That said, I think there are things that organic gardeners can do to give their plants the best chance at fighting things off. Excellent soil is a must. Things that you mentioned, such as not watering overhead, so make a difference. However, don't be afraid to try products such as Bt, Neem and Serenade. I think it's silly to continually fight a loosing battle (there's a good reason I don't grow squash vines in my low-light yard), but for the occasional problem, there are things that might help. These can be pricey though, so I wouldn't want to tell a gardener to always spray tomatoes with Serenade to prevent fungus, because as you pointed out, tomatoes often continue producing even when a fungal infection attacks. But if it comes down to the possibility of loosing your entire broccoli crop to caterpillars, I think a little Bt would be a wise move.

I think it comes down to the gardener knowing where their priorities stand, and working accordingly.

Ed Bruske said...

El, as usual you have such great intel. I never cease to be amazed how you keep track of everything with this mosaic of plantings you have in so many different locations. I did absolutely nothing to my tomatoes this year in terms of training or trimming them. They are in big cages made of concrete reinforcing wire, which give them room to grow up and out. Still, thinking the lower and interior foliage sounds like a good idea. What's the idea behind removing the upper blossoms?

De, I have to admit that I am really clueless about garden products, whether organic or no. I've never used any of them and really never saw any need. That may be because my garden is so isolated from any other vegetable garden. I hear about these kinds of problems much more from community gardeners, where everyone is growing the same thing year after year in close proximity. It's hard to get those gardeners to think in terms of pest management without some form of spray or chemical--strategizing, in other words, to avoid problems rather that applying something when the problem occurs.

Sylvie said...

I am with you. I practice many age-old techniques like you do (rotation, compost...), and I accept that some years will be better than others.... for something.

And there is enough poison around that selecting disease resistant varieties make a lot of more sense than spreading more poison around. Try different cultivars and see what works best for you. This is how heirloom came to be after all: plant selected for some desirable traits for a given locality and propagated from year to year.

Finding a balance in the garden will also make the gardening and the eating a lot more enjoyable.

Ed Bruske said...

Sylvie, right on. It's all about balance.