Prevention of Undesirable Fruit

Apples, pears, and cherries are examples of trees that produce edible fruit. Ornamental trees also produce fruit. In some cases, these fruit become annoyances. The green ash, honeylocust, crabapple, and ginkgo are popular ornamentals that may produce objectionable fruit. The best way to avoid objectionable fruit is to select fruitless varieties when available.

The green ash is a widely planted shade tree. It is hardy, adaptable, and fast growing. Fruit of the green ash are single-seeded samaras. The fruit are widely dispersed by the wind. The fruit become a problem when they begin germinating in perennial beds, hedges, and other garden areas. Often the only way to kill green ash seedlings is by pulling or digging them up. 'Patmore', 'Bergeson,' and 'Dakota Centennial' are excellent seedless greenash varieties.

The honeylocust is a native tree valued for its rapid growth and lacy foliage. Native honeylocust trees have vicious thorns and 6 to 12 inch pods. Select honeylocust varieties that are thornless and produce few, if any, pods. 'Shademaster,' 'Skyline,' 'Halka,' and 'Imperial' are recommended honeylocust varieties for Iowa.

Crabapples are popular spring-flowering trees that also produce fruit. The fruit of some older varieties, such as 'Hopa,' are relatively large. They drop to the ground in late summer. Fruit drop onto patios, sidewalks, and other areas can be quite messy. Many of the newer crabapple varieties produce small fruit that persist well into winter. The fruit are seldom a problem as robins, cedar waxwings, and squirrels do a good job of devouring the fruit. The only widely sold fruitless crabapple variety is 'Spring Snow.' Unfortunately, 'Spring Snow' is highly susceptible to apple scab which may cause considerable leaf drop by summer.

Fossil records indicate that the ginkgo has been growing on earth for more than 150 million years. The ginkgo is noted for its fan-shaped leaves and unique growth habit. The ginkgo is open and pyramidal when young, becoming wide-spreading and irregular with age. It is also relatively pest free. Ginkgoes are dioecious. Male and female flowers are borne on separate trees. Female trees produce tan, 1 to 1 1/2 inch, plum-shaped fruit. The fruit (actually fleshy coated seeds) drop to the ground after a hard freeze and produce an offensive odor. Some have described the fruit as smelling like rancid butter. To insure against unwelcome fruit, plant male ginkgo varieties, such as 'Princeton Sentry' and 'Lakeview.'

Little can be done to prevent the fruiting of trees currently growing in the landscape. Hormonal sprays, such as Florel Fruit Eliminator, may be effective in reducing or preventing fruit set on trees. These materials, however, are often difficult to obtain and results are often disappointing.

This article originally appeared in the April 28, 1995 issue, p. 50.


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