Saturday, August 22, 2009

Late Blight

Ugh - I think I have it. Well, I don't have it, but my potatoes and tomatoes do. "It" is late blight, that fungal disease that is sweeping the nation.

I heard about it here and there, but not having television, my exposure to it has been minimal. And I've been in denial. I couldn't possibly have late blight. I get my spuds from good sources, certified seed potatoes. I start my tomatoes from seed...heirloom varieties. None of my neighbors have gardens. Of course I was safe.

But lately I haven't been so sure.

Sure, every year some of my potato plants look poorly (shrivelled stems with no leaves), but I've attributed that to the potato beetles. Hm...could it be late blight?

And every year some of my tomato plants look poorly, but that was because it was so dry and hot, or wet and cool. Rot. And those brown spots on the fruits? Poor air circulation - that's gotta' be it.

Well, I decided to look up late blight today, just to be sure, and what I found was not good. And wet and cool seem to be key words.

Late blight, Phytophthora infestans, nails things in the Solonaceae family (potatoes, tomatoes, nightshades, et al). And it thrives in cool, wet weather, just like this summer.

To really know if you have this disease, you need to patrol your garden a couple times a week. Look for brown lesions on the stems or leaves of your tomato and potato plants. If you see it, destroy it! Look for white fuzziness - these are the spores. If you see it, destroy it! Look for dark, greasy-looking lesions on tomatoes. If you see it, destroy it! Look for brown spots and granular texture on your spuds. If you see it, destroy it!

The spores apparently spread with great ease on the wind. An infected plant can be dead within four days. The fungus can live in spuds that overwinter in the ground, for spuds are living tissue.

So, how are you supposed to destroy the plants? I finally found details for this, and there are several ways you can go.

1. Don't do anything until you have a sunny warm day. UV radiation, apparently, will destroy any spores that shake loose.

2. Pull up the plants and bag 'em. Leave them in a sunny location for several days. The heat will kill the fungus. Then send them to the landfill.

3. Pull up the plants and put 'em in a pile. Cover the pile with a tarp and let the sun bake the whole thing for several days. The heat will kill the fungus.

4. Pull up the plants and dig a really deep hole. Bury them.

5. You could compost them, provided your compost pile gets very hot. If not composted correctly, it could mean doom for your plants next year.

6. Infected spuds can be spread out on the ground and left there for the winter. Apparently the fungus can be killed by freezing. Freezing is not a problem here in the Adirondacks.

Also any plants (potato or tomato) that volunteer from last year's garden (like all those spuds that I missed that subsequently sprouted) should be ripped out (and destroyed - see choices above) before they really get going.

When you dig your spuds, look for infection. Even healthy-looking tubers (or tomatoes, for that matter) can be infected. So far research hasn't found any problems with eating healthy tissue, but you want to avoid ingesting infected tissues.

So, the next sunny day we get (next week?), I'll be yanking out all my tomatoes. I'll probably do the spuds, too. What a waste. >heavy sigh<

For more information, go to: http://www.nysipm.cornell,edu/pulications/blight/ . This is very informative. Also check out - a Fact Sheet of Frequently Asked Questions.

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