The Q&A Archives: Black Spots On Tomatoes

Question: I have black spots on my tomatoes and I am wondering if this is caused by a certain weather condition or if this is a bug. Either way is there some way I can prevent this?

Answer: Moisture on the leaves encourages the growth of fungal diseases that cause leaf spot. Water the soil, not the leaves, and water in the morning, if possible, so that any water splashed on the leaves can evaporate quickly. In addition, a good preventative measure is to spray your plants (this is the only time the leaves should be wetted intentionally) with a compost tea solution. To make it, mix one part mature compost that contains some manure with five parts water. Let the mixture sit in the shade for two weeks, then filter through cheesecloth and spray on plants. You can dilute the solution by half or use it full strength. Spray every two or three weeks. The residue leftover after filtering can be spread around your plants.

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