How to Manage Pests

Pests in Gardens and Landscapes

Blossom end rot

Plants with blossom end rot show small, light brown spots at the blossom end of immature fruit. The affected area gradually expands into a sunken, leathery, brown or black lesion as the fruit ripens. Hard, brown areas may develop inside the fruit, either with or without external symptoms. The disease is not associated with soil contact or with damage to other plant parts.

Solutions

Blossom end rot results from a low level of calcium in the fruit and water balance in the plant. It is aggravated by high soil salt content or low soil moisture and is more common on sandier soils. To reduce rot, monitor soil moisture to make sure that the root zone neither dries out nor remains saturated. Follow recommended rates for fertilizers. Some varieties are more affected than others. The disease is not caused by a pathogen; there are no pesticide solutions.

Start of blossom end rot on tomato fruit
Start of blossom end rot on tomato fruit
Sunken, leathery lesions on tomatoes
Sunken, leathery lesions on tomatoes
Rotting of zucchini
Rotting of zucchini

Statewide IPM Program, Agriculture and Natural Resources, University of California
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Agriculture and Natural Resources, University of California

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