What Are the Causes of Cucumbers With Shriveled Blossom Ends?

Black Rot Symptoms and Causes

• True to its name, black rot causes black decay, which usually initially forms at the fruit's blossom end. Areas affected by the black rot will eventually shrivel and dry up. Beyond the fruit, the leaves of the affected plant will often turn yellow. The rot may only affect certain areas of the plant, but can easily become systemic and kill your entire cucumber plant. Black rot is caused by the fungus Didymella bryoniae, which lives in organic matter or in the air. The fungus is often spread through open wounds in plants and through infected soil.

Black Rot Prevention

• Once black rot has taken hold of a cucumber plant, there is little that can be done to stop it. It is best to remove an infected plant from the area and destroy it so the fungus is not spread. Rotating crops will lessen the chances of the fungus surviving in soil and coming back season after season to destroy your cucumbers. Most importantly, since you can never be certain your soil is free of the fungus, be very careful not to wound the cucumber plant. If there are no open areas on the cucumber plant, there will be no point of entry for the fungus to infect it.

Belly Rot Symptoms and Causes

• Belly rot is caused by the fungus Rhizoctonia solani, which is found in most soils. Fruit becomes infected directly through contact with the soil. If your cucumber fruits are touching soil and their blossoms are beginning to rot, belly rot is most likely the cause. The blossom ends and underside of the fruit, where it touches soil, will begin to form moist, yellow lesions that will become sunken and soon begin to shrivel.

Belly Rot Prevention

• This fungal disease can easily be avoided by making sure your cucumber fruits do not come into direct contact with your soil. Once infected, there is little that can be done for individual fruits, but the fungus is not systemic and only individual fruits will become infected. Deep plowing may kill a large population of the Rhizoctonia solani, but you may lose beneficial fungi and bacteria in the process as well. A preventative fungicide will yield the same results. Laying down landscape cloth or some other barrier between the soil and your fruits is an effective preventative measure if your plants are not situated in such a way that they will not touch the soil's surface.