Eliminate tomato blossom-end rot on your garden tomatoes with Bonide Rot-Stop Tomato Blossom-End Rot Concentrate. Blossom-end rot appears as a round, brown sunken area on the end of the tomato fruit opposite the stem and is caused by a calcium deficiency. The blemish may also be aggravated by the application of too much nitrogen fertilizer, or by a period of rapid growth followed by dry conditions. When used as directed, this concentrate helps correct the calcium deficiency and is effective as a supplement to a regular fertilization program for your tomato, cucumber, pepper, and melon plants. Control the blossom end-rot in your garden with Bonide Rot-Stop Tomato Blossom-End Rot Concentrate.