Tomato end rot

Asked August 19, 2015, 3:49 PM EDT

Ron Gill called and has some tomato's that are turning dark on the bottom's. Is this end rot and can it be treated organically? He would prefer to be called at 336-3147.

Crawford County Pennsylvania

1 Response

Blossom end rot on tomatoes is a common problem and often thought of as a disease. The symptoms of this problem look like a leathery black end on the tomato. The tops of the fruit often look ripe and delicious.

This problem is not a disease, virus, or insect problem, but rather a nutritional issue. Calcium is a nutrient provided by the soil. Calcium helps the cell walls in the fruit to form. It moves through the plant by water. In the soil, it becomes even less accessible to the plant if the soil pH is too low. The ideal pH range for tomatoes is 6.2-6.8. When the plant is young, it uses less calcium. As the fruit begins to grow, more calcium is needed for the fruit to develop into a ripe tomato. Since the calcium is moved by water, and the fruit of a tomato becomes mature during the heat of the summer, more water is needed to allow more calcium to be available to the fruit. Hence, if you are not watering regularly during drier times, blossom end rot occurs.

Watering regularly during time of fruit development - approximately one inch per week - and adding calcitic lime to the soil if the pH is low will help insure a healthy tomato. If the problem occurs, your best solution is to pick the fruit that is affected and begin watering regularly.