Bloom Rot on Squash

Blossom End Rot

• Bloom rot on squash is usually called blossom end rot. As the name implies, this is a dry, dark rot at the fruit’s blossom end caused by a calcium deficiency. The lack of calcium may simply result from the soil containing an inadequate level of calcium or it may signify an inability of the plant to absorb calcium through its root system.

Calcium

• Test the soil before planting squash. If a calcium deficiency exists, applying lime helps restore the calcium content. Squash plants should not receive excessive fertilization in the form of large amount of potash or nitrogen, as these nutrients affect the ability of the roots to absorb calcium.

Rot Prevention

• The efficiency of squash roots in uptaking calcium increase if the surrounding soil is moist. Applying of a thick mulch layer helps ensure that the soil does not quickly dry out. Adding organic matter to the earth encourages a ready flow of calcium. Bloom rot is discouraged if squash plants are grown in raised beds that hydration balance.

Bloom Rot Management

• The soil’s pH level plays a role in blossom-end rot with calcium most easily absorbed when the pH level rests between 6.5 and 6.7. Foliar calcium sprays are not effective, as squash leaves cannot absorb calcium in this manner. The nutrient must be delivered by the root system. Whitefly infestations must be controlled, as these insects spread curly top virus, a disease that contributes to bloom rot on a squash.