Learn to pronounce this word -- phytophthera. That's fye-toe-FTHAIR-uh. You'll need to practice that "fth" sound. But there's nothing like throwing out a little Latin to make people think you know what you're talking about.

Phytophthera is the fungus that causes late blight, and it is the tip of everyone's tongue right now. Well, not literally -- that would be gross -- but everyone is talking about it. Forget swine flu; we're in a serious Phytophthera epidemic.

This is the disease that caused the great Irish potato famine in the 1840s and populated the police departments of several East Coast cities. I have no idea why only the Irish policemen emigrated to America.

Conventional wisdom says that the famine resulted because all the potatoes in Ireland were of a single clone, so there was no resistance. Truth is that we now have many genetic strains of potatoes, and they are all still susceptible to late blight.

Phythopthera hits all solanacious crops -- not just potatoes but tomatoes and eggplant and tomatoes and petunias and tobacco and tomatoes. Did I mention tomatoes?

Do not confuse this disease with early blight, which we all get every year. It makes the tomato plants look ugly and can reduce production in severe cases. Late blight kills the plants. Fast. Often within a week.

Part of the problem seems to be that the fungus was introduced by a couple of big growers who supplied the big box stores. All tomatoes had to be removed from chain stores in all the New England states and parts of New York. But mainly the problem is a weather phenomenon called a Smith Period.

A Smith Period is a 48 hour period with warm nights, not too hot days, and rain or high humidity. Those are the conditions for fungus spoors to sprout. We have not had a Smith Period, we've had a Smith Summer. Even my Volcano strain phlox, normally very resistant to powdery mildew, is white and fuzzy.

What can you do? Not a whole lot. You can use a fungicide like Immunox on your roses and other ornamentals. But once your tomatoes get late blight, you can only slow it down a little. The key is prevention, not cure.

I have been following an on-line discussion of preventive measures with other garden writers, and they speak as with one voice: "My method works and yours doesn't." I shall pass on some of the suggestions, eliminating only those which involve nudity and bonfires.

First, mulch your tomatoes deep with straw or grass clippings. This actually makes sense. The fungus starts when it is splashed by rain from the soil to the lower leaves. Mulch limits that. And prune off the lowest tomato branches.

Spray with liquid seaweed, which can be found in large garden centers. Do this once a week or after every rain or every day -- same thing, this year -- depending on which expert you believe. Worth a try, because seaweed has a number of other benefits anyway.

Or spray with a mix of one part milk and three parts water. Same frequency as the seaweed. Seems to me your garden would smell like sour milk, but some swear by it. Or compost tea. Or horsetail tea; I assume they mean the plant, not real horse's tails.

These are preventive measures, before you get it. If you already have it, you need something with copper in it like Bordeaux mix. And pick off all the infected leaves, for what good that will do you. Some claim copper is a cure, others that it will just slow the disease spread, which might be enough to get you some tomatoes.

If none of this works, you might as well try that bonfire thing. Let me know when and where.

-Duane Campbell, a nationally known agricultural expert, can be reached at R6, Box 6092, Towanda, PA 18848 or by e-mail at dcamp@chilitech.net for questions or comments.

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