Black spots on tomatoes

Asked June 6, 2018, 8:43 AM EDT

I assume these are some sort of mold or fungus. We planted a grape tomato plant on our deck. Plant doing well but a lot of fruit has these spots. How do I handle? Len

Jefferson County Kentucky

1 Response

Growing tomatoes can be economical and fun, but it can be frustrating when the plants develop problems. Many times it is disease related but occasionally it is due to growing conditions. Keep in mind these may occur on peppers, too. This is a common disorder called blossom end rot. It is caused by a calcium deficiency with-in the fruit.

Pick and discard all affected fruit to allow the plant to keep producing blooms and new fruit.

Blossom End Rot - The bottom of fruit develops a brown leathery skin. This is due to a calcium deficiency during fruit development. Generally the problem is not insufficient soil calcium levels but rather inadequate soil moisture preventing calcium delivery to the plant. Consistent irrigation is the control. Mulching the plants will help with soil moisture consistency.

For detailed information on both physiological and disease problems on Solanaceous Crops in Kentucky:

http://www2.ca.uky.edu/agc/pubs/id/id172/id172.pdf

Feel free to contact our office if you have other questions.

Let me know if I can help you further!


Carol Wilder
Horticulture Technician
Jefferson County Cooperative Extension Service
Email: carol.wilder@uky.edu

502-569-2344
200 Juneau Drive

Louisville KY 40243