Blossom End Rot (BER) is not caused by an insect or disease; rather, it is a physiological disorder often caused by a calcium imbalance within a plant (most commonly tomatoes…but peppers, melons and eggplants may also be affected).

IDENTIFICATION: BER starts as a sunken, dark spot on the blossom end (bottom) of the fruit. The spot gets larger and more leathery as the fruit matures.

CAUSE OF BER: Several factors may contribute to blossom end rot. Planting too early, when the soil is cold, may cause early fruits to have BER. Cultivating the ground too closely to the tomato plant may damage the feeder roots near the surface and cause it. Uneven moisture levels in the soil may contribute to it. A lack of calcium, or the inability of the plant to utilize the calcium due to a low pH level, is often the culprit. Plants which are growing rapidly and then are suddenly exposed to drought conditions are especially susceptible.

WAYS TO PREVENT BER: Check the soil pH; ideal levels are 6.5 to 6.8. Adding gypsum to the soil will add calcium without significantly changing the pH level. Adding eggshells to the soil will also add calcium to it. Use a low nitrogen fertilizer; nitrogen made from ammonia can disrupt the soil chemistry. Mulch your tomatoes and keep the soil moisture level even.

WAYS TO TREAT BER: A liquid calcium supplement can be sprayed on tomato plants with affected fruits. Carefully remove any tomatoes showing signs of BER; they will not be edible. BER does not spread from fruit to fruit or from plant to plant in your garden.

RESISTANCE TO BER: There are no varieties totally resistant to BER; however, you may find that some varieties you grow may be more or less inclined to have the problem. By planting after the ground warms up in the spring and by keeping your moisture levels consistent, you can often reduce the problem.