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Battle Plum Pox in Pennsylvania
By Jan Suszkiw
September 18, 2001
Near historic Gettysburg, Pa.,
federal and state scientists are facing down a different kind of threat than
that once posed by General Robert E. Lees Confederate troops: an exotic
stonefruit disease called plum pox thats invaded orchards in
Pennsylvanias Adams, Cumberland and York counties.
When and how it arrived there--possibly from Europe--remains speculative.
Fortunately, even before its U.S. presence was announced in October 1999,
U.S. Department of Agriculture scientists
had already begun researching the disease in anticipation of its arrival. Soon
after the announcement, they teamed with scientists from the
Pennsylvania Department of
Agriculture and Pennsylvania State
University to better tackle this new threat to the nations $1.8
billion stonefruit industry.
Through research on six basic fronts, including identification of aphid
carriers and herbaceous weed reservoirs, theyre helping to eradicate plum
pox from the affected counties and devise strategies by which U.S. orchard
managers can cope with the disease should it recur elsewhere, according to
Vernon Damsteegt, a plant pathologist with USDAs
Agricultural Research Service.
Plum pox poses no danger to consumers. But it can ruin the marketability of
plums, peaches, apricots and other stonefruits by causing acidity and
deformities. Adams, Cumberland, and York counties in Pennsylvania are the only
U.S. locations where plum pox (strain D) has been reported.
Since spring 2000, Pennsylvania researchers have been surveying orchards in
the affected and neighboring counties to determine which aphid species occur
there. At ARS Foreign
Disease-Weed Science Research Unit in Fort Detrick, Md., Damsteegt and PSU
scientist Frederick Gildow test the aphids to determine which actually transmit
plum pox to plants. One confirmed accomplice is the green peach aphid.
Meanwhile, ARS horticulturist Ralph Scorza in Kearneysville, W.Va., is
checking the susceptibility of native and ornamental Prunus species.
Both studies will help scientists find, and break, weak links in the plum pox
disease cycle, as well as monitor any possible spread to woodland areas or
A longer story in in the
issue of Agricultural
The research is part of the ARS National Program on plant diseases.