Anthracnose spores are spread by the wind, rain, insects, or by people working among wet plants and spreading the disease.
The spores can enter through wounds or penetrate the leaf or stem surface during wet conditions.
Anthracnose appears in the Eastern and Central U.
S and Southeastern Canada.
It doesn't seem to be a big problem in arid regions.
Dark spots or lesions, often sunken and wet looking, are characteristic of anthracnose, followed by formation of pinkish or salmon colored spores at the center of the lesions.
Tomatoes develop sunken spots with concentric rings.
Spores may form at the center of these spots, thus making them able to be transferred if not properly disposed of.
Secondary rot may set in and ruin the tomatoes.
Seedlings that sprout from seeds infected with anthracnose may show symptoms similar to damping off.
The best way to protect your tomatoes from anthracnose is to remove infected parts or the whole plant.
Stop using sprinklers to water your tomatoes from overhead, water at the base and root zone of the plant.
Spraying with sulfur will prevent the spread of anthracnose, but since the disease spreads mainly during wet conditions, it is difficult to apply the spray efficiently.
Check your tomato plants daily at harvest time and harvest the tomatoes as soon as they ripen.
Tomato fruits develop symptoms after harvest due to infection by spores on the surface of the fruit at harvest.
To prevent spread, wash and dry all healthy looking fruits as soon as you bring them inside.
Keep infected fruit separate from healthy fruit.
You need to practice good gardening techniques to prevent the spread of anthracnose.
Clean your garden of debris both during the growing season and at the end.
Anthracnose fungi survive the winter on seeds, weeds, and garden debris (especially infected tomatoes that have dropped off the vine and allowed to seed).
When the harvest is complete, discard all of the infected remains.
Be alert during the growing season to discard tomatoes that fall off the vine, don't just let them lay there or there will be seeds left over in the ground when the tomato decomposes.
Choose resistant varieties whenever possible.
Also, if you didn't clean up all of the fallen tomatoes the year before, keep an eye out for the seedlings that they produce the next year.
Uproot and discard them as soon as you spot them.
Allow the proper spacing between your tomato plants and stake them to allow for the proper air circulation.
Try preventive sprays of Bacillus subtilis.
As for crop rotation solutions, do not plant tomatoes in a spot that had any member of the nightshade family (peppers, eggplant, potatoes) there the previous year.
If you do have a problem with anthracnose, skip planting tomatoes in the same spot for at least two years, the disease should run its course by then.