Like many gardeners you may have had problems with gray spots on tomatoes this year. This is due to a widespread epidemic of a fungal disease called late blight. Southern states were especially hard hit. See What Caused Texas Tomato Plants To Die. Late blight causes gray spots on tomatoes which have a greasy appearance and causes tomato plants to wither and die and not produce fruit.

What is this disease called late blight that causes gray spots on tomatoes? Late blight was first identified in the mid 1800′s when it was found to be the cause of the Irish potato famine. This widespread famine affected potatoes across Ireland, which were the main source of food. The same potato fungus causes gray spots on tomatoes and rotten flesh in the fruit.

What To Do About Gray Spots On Your Tomatoes

If your tomatoes have gray spots like the ones in the photo above, you may have an infestation of late blight fungus in your garden. Depending on how far gone the plants are, you may be able to stop it with an application of fungicide or copper spray.  My county extension agent recommended that I treat any plants which showed the first signs of late blight with Serenade Anti Fungal or a copper based spray. If the fungus is on all of the tomatoes and plants you should remove them all from the garden and place them in a garbage bag to be hauled away. Don’t compost tomatoes or plants with late blight.  Also, to prevent spreading the fungus to other tomato plants, don’t walk through a dew covered tomato patch touching other plants. Clean all shears, hoes, rakes, that were used with alcohol.  If you see tomatoes with gray spots in your garden you should act quickly to prevent the spread of late blight to your garden and that of your neighbors.