Asked April 14, 2017, 8:45 AM EDT
We get blight every year. We've sprayed with copper sulfate, put the in planter on deck, put them on carpet in planters, fresh dirt several times, moved areas in yard.Can we fix the problem?
Crow Wing County Minnesota
Sounds like you are doing a good job, replacing soil in containers, etc. Not sure if you have other plants with blight, peppers, eggplants, or potatoes, etc. in the area? The copper spray is a good treatment.
It occurs to some extent every year wherever tomatoes are grown. In spite of its name, the disease may occur at any time during the growing season. The fungus attacks leaves, stems and fruit. It can also cause disease on potato, pepper, and eggplant. Alternaria solani can survive from year to year in old, diseased vines left in the field. Splashing rain, running water, and even hands can spread the fungus. Symptoms are usually visible about 10 days after the plants are infected. Infection takes place slowly unless the plants have been weakened or wounded.
Space plants to allow good air circulation, thereby permitting plants to dry off rapidly after rain and dews. This will reduce the risk of disease development. Pruning the lower leaves and infected leaves asap. Disinfect your scissors with alcohol that you use to cut infected plants.
Remove infected leaves as well. Keep watering at the soil level to avoid splashing the leaves. Covering the soil with straw or something that can be replaced helps with water splash. With the rainy, moist spring weather the past few years it has been a problem. Also make sure you are purchasing plants from a good grower and if you always plant the same variety of tomato try a different one. Some are more resistant than others.
You probably won't be able to get rid of it completely but you can stay on top of it. Here is a link that you may find helpful.