
A Dwarf Pear Tree: Another Genetic
Engineering FirstBy Judy
McBride July 2, 1999The first genetically engineered dwarf
pear tree of an existing variety has been developed by
Agricultural Research Servicescientists. Dwarf trees are more productive than traditional-size trees and
offer growers other advantages as well. ARS horticulturists Ralph Scorza and Richard Bell at the
Appalachian Fruit Research
Station in Kearnesyville, WV, dwarfed Bosc pear trees by inserting a gene
originally isolated from a bacterium. The new dwarf trees are growing in
greenhouses at the lab, and the scientists expect the trees to bear fruit in
about two or three years. The bacterial gene can be used to dwarf rootstocks or to make the
scionthe top part of the treesmaller or dwarf. According to Bell,
the pear industry relies on only a few major varieties and needs to improve
them. Dwarfing will do that. In addition to being more productive, dwarf fruit trees allow high-density
plantings of smaller trees that can produce more fruit in the same area of land
than the larger, standard-size trees. And theyre easier to manage, prune,
spray and harvest. Fruit from a dwarf tree is the same size as fruit from a
normal tree. For those growers not interested in dwarf trees, Scorza and colleagues have
developed a peach tree with a new, columnar shape. Perfect for the home
gardener with limited space, the columnar tree has upright, narrow branches
that grow close to the tree trunk without shading other fruit or vegetables
that may be growing nearby. Like dwarfs, the columnar trees require much less management and will allow
high-density growing. They eliminate the large space necessary between
traditional trees. Therefore, chemicals and fertilizer need be applied only to
a very small area, saving the grower money and reducing environmental impacts.
Compared to traditional size trees, at least three times as many columnar trees
can be grown per unit of land. These new treeswhich bear excellent quality fruitare expected to
be available to home gardeners within the next few years. ARS is USDAs chief scientific
research agency. A more detailed story on this research is available in the
agencys July Agricultural
Research magazine, available on the Internet at: http://www.ars.usda.gov/is/AR/archive/jul99/fruits0799.htm Scientific contact: Ralph Scorza and Richard Bell, ARS Appalachian
Fruit Research Station, Kearneysville, W.Va.; fax (304) 728-2340; phone (304)
725-3451, Scorza (Ext. 322), Bell (Ext. 353),
[email protected],
[email protected]. Story contacts Richard L Bell Ralph Scorza U.S. Department of Agriculture | |