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tomato blight

Posted: Fri Jul 03, 2015 1:38 pm
by LesSmith
Our tomato patch has the blight and we are not planting tomatoes there for the next two years. Is that sufficient time for the blight to die off? Also, would planting peppers and watermelons in the patch allow the blight to stay viable?
We have a potted tomato growing on the patio and a black area has appeared on the stem; leaves show no sign of distress. Have attached pictures. Does anyone know what this is, and if it can be cured?
All have an enjoyable and safe Independence Day weekend..

Re: tomato blight

Posted: Tue Jul 14, 2015 3:45 pm
by lorijones
Blight diseases, including late blight and early blight, are fungal diseases that are spread by spores that are found in the soil and on plant debris that is left in the garden. The spores infect plants when they are splashed up on the stems and leaves, germinate, and begin to grow. The spores can remain viable in the soil for four years or perhaps longer. It is usually recommended to practice crop rotation on a 4-year cycle to avoid or at least reduce the incidence of soil borne diseases and insect pests. When crops are rotated, you avoid planting vegetables of the same family in the same section for four years. Since peppers are in the same family as tomatoes (and also eggplants and potatoes), I would not plant them in that section. It would be fine to plant watermelons there.
When you plant tomatoes in your tomato patch again, be sure to mulch them well to prevent any soil from splashing up on the tomato stems and leaves. I put down several layers of newspapers and then straw on top of the newspaper. It works VERY well! It also keeps the weeds down and helps keep even moisture in the soil around the plants. Water the garden in the middle of the day so that the foliage has a chance to dry more quickly. It is also a good idea to plant varieties that are disease resistant.

The stem lesion on the tomato in the pot looks very much like the lesions that can form as a result of one of the blights, perhaps late blight. It is interesting that there are no symptoms on the leaves. It might be good to spray with a fungicide like Bonide Liquid Copper or Fung-onil or Daconil as a preventative measure.