In the Garden:
Middle South
July, 2003
Regional Report

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Rain helped give my tomatoes a terminal case of late blight. To prevent problems next year, these plants are on their way to my sick plant graveyard in the woods.

The Fungus Among Us

It's been a soupy summer so far -- wonderful for our forests, which have suffered from drought for the past four years. The forests may be happy, but prolonged dampness may be taking its toll on your garden. It's a good time to get to know the fungus among us.

Leafspot Life Cycles
Most of the fungi that cause leaf spots on plants – including blackspot of roses and the late blight that's ruining my tomatoes – reproduce by making thousands of powdery spores. These spores spread to new leaves constantly, yet most of them cannot come to life unless the leaf surface is wet. But given a little water, the spores germinate and use enzymes to break down cell walls and get inside the leaves. Next thing you know, the dark spot that appeared yesterday is releasing fungal spores that will infect more leaves tomorrow.

Gentle Interventions
The most direct way to limit fungal problems is to remove infected leaves as soon as you see them. Use pruning shears or a small pair of scissors to snip off leaves that show spots, and dispose of them far from your garden. Work when the leaves are dry to avoid spreading the spores. Older leaves are easy prey to fungal diseases, so it's a good idea to trim them off at the first sign of trouble. If entire plants appear sick, either pull them out or prune them back hard.

Fungicides can help with leafspot diseases when they are used before a disease becomes well established, but they are of little help to badly infected plants. As an alternative to chemical fungicides, a baking soda spray can help prevent outbreaks of leafspot diseases. Mix 1 teaspoon baking soda in a quart of water, add a few drops of dishwashing liquid, and spray it on plants that are at high risk of developing fungal diseases.


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