Much faster production of fruit-bearing peach trees may soon facilitate high-density orchards in which 500 to 700 small trees are planted on each acre instead of the usual 150 to 180 trees, according to Dr. Freddi Hammerschlag, USDA Beltsville Research Center scientist.
It will be accomplished by micropropagation techniques, she says. Although this high-density management has been shown to be more productive, until now peach trees have been too expensive and too large to use in this new system.
Hammeschlag has found that with micropropagation she can use a tiny shoot from budwood to produce five to ten shoots every six weeks. Each new shoot can be used to produce many more shoots. If virus-free budwood is used, disease free plants can be achieved.
Traditionally, peaches have been propagated by grafting since peach seeds do not reproduce all the characteristics of parent trees and peach cuttings from most varieties are very difficult to root. In grafting, buds from last year's growth (budwood) are grafted into the stem of one of a few types of peaches produced from seed (rootsticks). This procedure is costly and time-consuming.
Four improved cultivated varieties of holly developed at the National Arboretum (USDA Research) by Gene Eisenbeiss are now available to commercial growers and home gardeners: Clusterberry, September Gem, Sparkleberry and Apollo, according to USDA Science and Education Administration.
Clusterberry is a moderate-sized and broadly branching holly. Its name refers to the tight clusters of 4 to 12 berries that encircle the end of each stem. It grows well in both shade and sunlight, has considerable heat tolerance and is well suited to the southeast.
September Gem, compact, slow-growing, and broadly conical, is especially suited to city gardens, entrance ways, and other limited planting areas. Named for the exceptionally early ripening of its showy red berries, it is heat and shade-tolerant and will grow well in a wide range of soils.
Sparkleberry, large, fast-growing and deciduous, is the result of a 1962 cross between two wild hollies. It is named for its brilliant, glossy fruit which often remains on the shrub will into March.
Apollo was selected and bred to provide Sparkleberry with a reliable pollinator. Similar to its sister variety in growth habit, size and shape, it does not produce berries but instead yields a profusion of small white flowers with conspicuous yellow stamens that are attractive from a considerable distance. The leaves turn an attractive yellow in fall. Both are shade and sun-tolerant and grow well in a variety of dry and wet soils.
Growing Irish potatoes in the rain-fed northeast requires large quantities of pesticides for insect, disease and week control. Conservative estimates put the cost at from $100 to $300 per acre. This means that growers with 100 acres of potatoes were paying from $10,000 to $30,000 per year for pest control.
In addition, the high quantity of pesticides used pose environmental problems, the consequences of which may not be fully realized until some future date.
Two pest managements systems were developed by Penn State scientists to provide forecasts for timing of fungicide applications to control potato late blight and green peach aphids: Blite-cast and GPA-cast. In 1980 both were combined into a single computer program called Spud-cast.
The Spudcast procedure involves setting up a Spudcast station.
A hygrothermograph and a rain gauge collect weather data. The data needed includes daily maximum and minimum temperature, hours of relative humidity above 90 percent, maximum and minimum temperatures during the high relative humidity period, and rainfall in 1/100 of an inch. This data -- along with the number of green peach aphids, crop values, and spray costs -- are required to process and obtain recommendations for potato late blight and green peach aphid.
The station converts the information into usable form for the grower and provides a recommendation for spraying.
The hand-held programmable calculator manufactured by Texas Instruments (T.I.59) and the Radio Shack TRS-80 home computer system are used to deliver the control recommendations to the grower. A pencil and paper technique and microcomputer also are available.
Recommendations indicate whether a spray is needed and the frequency of application. When blight-favorable weather exists, an update can be obtained for part of a week. Future abundance of green peach aphid and its economic status can be determined from weather forecasts.
Much more needs to be accomplished to develop a total pest management program for potato production, the scientists say. One of the areas presently being researched at Penn State is development of an "action threshold" for Colorado potato beetle, telling growers when to spray.
Integrated techniques and crop management practices are being developed and tested to reduce the incidence of disease and chemical effects on nontarget organisms. From these studies, the most effective use of pesticides, immediate and long-range, will be obtained.