News Release
Sept. 3, 2007

Landscaping Tips: Good gardening practices help prevent blossom-end rot

By Jim Gill, extension educator, UW CES

This time of year, some gardeners across the state are bringing tomatoes, peppers and other vegetables having weird looking, dark-colored spots into University of Wyoming Cooperative Extension Service county offices.

The gardeners are wondering what causes the spots, how they can be prevented and if vegetables with such spots can be consumed.

Quite often, the spots are caused by a physiological disorder called blossom-end rot. This is a common problem in tomatoes, peppers, squash, eggplant and some melons.

The affected vegetables will have water-soaked areas and decay near the blossom end of the vegetable. These areas become enlarged and turn brown to black. This is due to the fungi and bacteria that often colonize on the distorted tissue.

This problem is often referred to as “vacationers disease” because folks leave the garden for an extended trip or vacation in summer when the vegetables need watering the most. The plants become stressed, making the plant more susceptible to insects, diseases, fungi and other problems. To help avoid such problems, ask a reliable friend to irrigate your garden during your absence.

The primary cause of blossom-end rot is a calcium deficiency at the growing point of the fruit. This deficiency causes deformity at the blossom end. While affected vegetables are unsightly, the unaffected portions are safe to consume.

Several environmental and management factors contribute to blossom-end rot.
Poor root growth caused by continuous watering will reduce calcium uptake by the plant. Providing adequate water to saturate the root zone of the plant once or twice a week is sufficient.

Management practices that aggravate the problem include setting out transplants when soil temperatures are below 50 degrees. Injuring roots by cultivation or hoeing is often associated with the problem; however, the biggest factor is improper watering.

The key to blossom-end rot prevention and control is to maintain uniform watering and fertilization schedules. In general, a mixed fertilizer ratio of one part nitrogen to three parts phosphate is ideal. Water deep, and avoid light, frequent irrigation. A 10-inch screwdriver can be used to help assess soil moisture conditions in the garden. If the screwdriver can easily be pressed into the soil, this indicates adequate moisture. Conversely, if it can only be pressed into the soil an inch or so, it is time to irrigate.

If you have other questions about blossom-end rot or other gardening-related items, contact your local University of Wyoming Cooperative Extension Service (UW CES) office. Contact information is at http://ces.uwyo.edu/Counties.asp

Another good resource is the UW CES Horticulture Web page at http://ces.uwyo.edu/PUBS/Horticulture/Horticulture_Publications_Main.htm.

Among the bulletins are Gardening: Vegetables in Wyoming, B-1115, and Gardening: Extending the Vegetable Growing Season, B-1148. These bulletins can be downloaded free or are available from CES offices.

Copies can also be ordered by e-mailing cespubs@uwyo.edu.
 

Contact: Robert Waggener, Editor
Phone: (307) 766-3571
E-mail: robertw@uwyo.edu

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