Zucchini Growth Problems

Zucchini grows well during the warm season.

Zucchini squash, a main ingredient in many Italian dishes, thrives in warm weather. This summer squash is similar in appearance to the cucumber and ranges in color from a green so dark it appears black to a creamy pale green with light-colored flesh. Unlike its vining relatives, many zucchini varieties grow on bushlike plants compact enough for the smaller urban garden. To keep plants healthy and productive, gardeners need to watch for signs of common pests and problems.

Pollination Problems

Zucchini plants have both male and female flowers. The male flower is attached by a thin stem, but female flowers sit close to the plant on a small round ovary or unfertilized fruit. Bees and other insects transfer pollen from the male flower to the female flower, fertilizing the ovary creating fruit. A lack of bees to transfer pollen between the flowers results in little or no fruit. Poor pollination can also result in deformed fruit. Gardeners can pollinate the flowers manually, transferring pollen from the male flower to the female flower with a cotton swab.

Cross Pollination

Zucchini can cross-pollinate with other varieties of squash grown nearby such as pumpkins or acorn squash. This cross-pollination does not affect the current crop of zucchini. However, this cross-pollination does affect the seeds of the crop. If planted, these seeds may produce a "pumzini" or some other kind of crossed, unappetizing fruit.

Pests

Zucchini is susceptible to squash bugs, squash vine borers and striped cucumber beetles. Squash bugs suck the sap out of leaves with piercing-sucking mouthparts. Their feeding interrupts the flow of water and nutrients through the plant, causing wilting and possibly even death. The larvae of the squash vine borers bore into the stems of the plants to feed, preventing water from reaching the rest of the plant. Left unchecked, the wilting plant eventually collapses and dies. Both the larvae and the adult striped cucumber beetles feed on the leaves of the plant. However, the adult striped cucumber beetles can also infect the plant with bacterial wilt, which is a fatal plant disease.

Diseases

Common diseases that affect zucchini plants are bacterial wilt, powdery mildew and yellow mosaic viruses. A plant infected with bacterial wilt will ooze a milky white bacterial substance when cut. Once infected, the plant cannot be saved. Powdery mildew is a fungus that appears as a white powdery growth on the underside of a leaf and spreading to cover the entire leaf. Powdery mildew stunts plant growth, distorts leaves and affects the quality and flavor of the fruit. Yellow mosaic virus is transmitted by aphids. The leaves of an affected plant have a yellow mosaic pattern, the fruit is small, mottled and malformed, and growth is severely stunted.

References

• University of Minnesota Extension; Growing Zucchini and Summer Squash in Minnesota Home Gardens; Vincent A. Fritz, et al; 2009
• University of Illinois Extension; Common Vegetable Gardening Questions; Sandra Mason; July 2006
• Cornell University Vegetable MD Online; Virus Diseases of Cucurbits ; T. A. Zitter, et al; October 1984
• University of Minnesota Extension; Squash Bugs in Home Gardens; Suzanne Burkness and Jeff Hahn; 2007
• University of Minnesota Extension; Squash Vine Borer Management in Home Gardens; Jeffrey Hahn and Suzanne Burkness; 2007
• University of Minnesota Extension; How Do Those Bugs Eat?; Charlie Rohwer; June 2005