You’re an eager home gardener who has lovingly nurtured a tomato patch from seed to fruit. But alas, just as your mouth waters for the first ripening gems, a black, leathery spot appears at the base of the fruit.
Blossom end-rot is thankfully a frustrating disorder and not a disease of the fruit. The black scar tissue is caused by a deficiency of calcium in the developing fruit, usually brought on by extreme fluctuations in soil moisture. And we seem to be going from an extreme of too much water to an extreme of too little water rather early this year, so blossom-end rot is likely to be prevalent.
The spot develops on the blossom end of the fruit, opposite the point of stem attachment, thus the name blossom-end rot. The scar is usually firm and leathery, although secondary rotting organisms may enter through the damaged tissue and cause a soft rot to develop.
Tomatoes aren’t the only fruits affected by blossom-end rot; summer squash and other cucurbit-type plants are less often affected.
Newly developing fruits can be helped, but those that have already developed the scar cannot. Since most tomatoes are still in the early stages of flowering and fruit formation, you can try to prevent blossom-end rot before it gets started. Watering during dry spells and mulching to conserve soil moisture will help reduce fluctuations in the moisture supply, preventing calcium deficiency in the fruits.
There is no spray that will control blossom-end rot, except maybe from the irrigation hose. Most Indiana soils have plenty of calcium, although some sandy soils may be deficient.
Reviewed 7/12/02; Released: 6-4-98