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Old July 13, 2010   #7
duckfan
Tomatovillian™
 
Join Date: Jun 2010
Location: Long Island formerly zone 6
Posts: 61
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Late Blight has three requirements;
1) A host plant
2) the presence of the disease
3) weather conditions favorable to the spread of the disease.
In any of the conditions aren't met, you can't have Late Blight.

I am growing tomato plants.
I have a recent confirmed case of Late Blight less than 5 miles from my garden.
The weather here is scheduled to be damp and cooler.
I sprayed Sunday night. I will be doing it again on Saturday but only because of all the rain I've had so far this week. If there are no new cases reported locally before the end of July, I am going to assume the disease is no longer present and I will probably discontinue my precautionary spraying.

If you don't meet any of the three conditions listed above, why are you spraying? If you have hot, dry weather and there are no reports of the disease within 100 miles of your garden, I think you're safe.The information you need to make an intelligent decision is readily available.

Late Blight is a relatively rare disease. Even among those of us who see it every year, most don't see it until late in the season after we've harvested most of our tomatoes. In that case our weather is getting cooler and the disease is brought North by Tropical Storms. We could spray and prevent it but why bother? In the very worst case we only lose a few days of production. It's true that a lot of us lost plants last year but most of that can be attributed to the infected plants imported and sold by Bonnie Plants. There is no debate. They caused the epidemic. They were the Typhoid Mary of last year's problem. Even though the one case reported in my area this year was on Bonnie Plants, the rest of them appear clean and there has only been one confirmed case. I hope it's the only one.
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