Backyard Local: Fight Tomato Blight

Warning to all backyard gardeners: there is a serious epidemic of late blight this year affecting tomato and potato plants. This is the same fungus that caused the Irish Potato Famine, and a combination of conditions this year (wet weather and contaminated tomato plants sold at places like Home Depot) have made this the worst outbreak of late blight in decades. Our CSA, Brookfield Farm, just mowed down all their potatoes in the hopes of saving the tubers and preventing the spread of the fungus to their tomatoes.

What makes this fungus particularly pernicious is that its spores are airborne, passing from plant to plant on the breeze. If you have tomatoes in your garden, regardless of where you got them, please go out and check them for blight. See www.longislandhort.cornell.edu/vegpath/photos/lateblight_tomato.htm for pictures of late blight. Look for brown patches on the stem and wilting leaflets around it. If you find blight, remove ALL affected foliage immediately. If it's in the stem, you will likely have to remove the entire plant.

Do NOT put infected foliage in your municipal yard waste, where the fungus can infect their mulch and compost. Bag it and throw it away. In New Mexico, we'd burn it, but I doubt that's allowed around here.

If you have other tomatoes or parts of tomato plants that show no blight yet, spray it with fungicide immediately and after every rainfall (yes, this is a pain, but, o! the horror of a summer with no tomatoes). There are many recipes for homemade fungicide, including:

• http://site.cleanairgardening.com/info/recipe-for-home-made-fungicide.html
• http://answers.yahoo.com/question/index?qid=20090619125802AABbIUf (you can substitute dishsoap)
  

Or you can buy this organic fungicide: http://www.cleanairgardening.com/greencure.html. Brookfield Farm is using copper as a fungicide.

Here's a good FAQ on late blight and how to deal with it: http://www.longislandhort.cornell.edu/vegpath/lbfaq.pdf

Also, keep in mind that there are plenty of other fungi around to prey on your tomatoes. The tomatoes in my community garden have early blight, and I'll be directing our gardeners in foliage removal and fungicide spraying this afternoon. Early blight is much less deadly than late blight, but it can transfer to other species like eggplants. It's treated in the same way as late blight, although treated plants are much more likely to survive. Tomatoes are going to be precious and rare at farmers' markets this year, so it will be well worth it to maintain your own love apples. And squash plants of all kinds are likely to be affected by fungus as well, so it's worth checking your squash for a white dusting on the leaves and treating it with fungicide or at least soapy water.

On the plus side, all the rain has had other benefits. Our greens, carrots, cucumbers, beans, and squash are going crazy, and despite the cool temperatures, I've got a lot of peppers and eggplant (hurray for black row covers). And for the first time this year, we had a noticeable blueberry harvest (we suffer from alkaline soil, but we seem to have finally brought up the acidity enough - sulfur helps, too) and will harvest our first lingonberries ever!

Side note: if you have midsummer-bearing raspberries, they should be running out of fruit right now. Once the fruit is gone off the canes, you should prune away the fruitbearing canes, leaving the new canes (those with no little stubs from the fruit) to grow as much as possible before winter. These non-fruiting canes will bear fruit next year. Removing the old canes means the roots only have to support the new canes, and they will be healthier and more prolific next summer.