Jul 6, 2010

New York state still fighting plum pox

New York state field survey crews place collected leaves directly into a cooler. Leaves are kept chilled from the time they are collected in the field to the time they are tested in the lab in order to keep the samples viable. Photos: New York State Department of Agriculture and Markets

New York state is commencing its largest survey to combat plum pox virus, a serious plant virus that infects stone fruit trees, reducing fruit yields and disfiguring fruit to the point that it becomes unmarketable. New York is the only remaining state in the nation with plum pox, according to a press release from the state agriculture department.

“We are fortunate to be able to utilize $1.3 million in federal funding to ramp up our surveillance efforts and initiate the largest, most aggressive survey to date to knock this virus out of our orchards, ensuring healthy and marketable growing stock and a viable future for our stone fruit producers in New York state,” said Patrick Hooker, the state’s agriculture commissioner.

Over the course of this summer, 30 state field surveyors will be collecting more than 227,000 samples in the eradication zone and outside of it to determine the exact location and severity. The current eradication zone includes Wayne, Niagara and Orleans counties – all locations where the virus has previously been detected.

In addition, surveys will be taken in Chautauqua County and the Finger Lakes, popular growing regions of stone fruit. An additional 23,000 samples will be collected from homeowner trees by USDA staff.

Field survey crews will collect leaves from Prunus species stone fruit, including peaches, apricots, nectarines and plums. While cherries are also considered stone fruit, they are not naturally infected by the strain of plum pox found in North America. Prunus species trees within 5 miles of a previous infestation will be sampled, and 25 percent of the trees will be sampled beyond the 5-mile perimeter. Collected leaves are kept chilled and shipped overnight to the New York State Agricultural Experiment Station in Geneva. Under the direction of Marc Fuchs, a plant pathologist at the station, the submitted leaf samples will be ground and tested for the presence of plum pox. There is no visual way to reliably detect for this virus.

Plum pox first appeared in the United States in Pennsylvania in October 1999. Since its discovery, the virus has spread to New York, where it was first detected in a Niagara County orchard in 2006. The virus was also detected in Michigan in 2006; Michigan’s small infestation was eradicated. Last summer, Pennsylvania successfully eradicated the virus, leaving New York as the only U.S. location with the virus; however, it is also present across the border in Ontario, Canada.

While plum pox does not pose any human health risks, the virus causes symptoms in the leaves and the fruit that reduces the quantity and quality of fruit. The virus makes the trees more susceptible to other insects and diseases, which will ultimately kill them. The virus also has the ability to infect wild native species and weed species. Aphids can serve as carriers of the virus.

The virus stays viable in the aphid’s mouthparts for a period of approximately one hour and most aphids can generally transmit infection moderate distances from the initial source plant.

The only method of eradication is to remove the infested plant material. Orchard and nursery growers of plum pox-impacted Prunus species can be compensated for their loss through an 85-15 federal-state cost-share program.
New York state has more than 4,000 acres devoted to peaches, nectarines, cherries, plums and apricots. The state is ranked 17th in the nation for peaches, producing 11 million pounds that were valued at $4.8 million in 2008, according to the press release.