A new disease could sour Georgia's sweet peach crop. Strict preventive measures have kept it out of the state so far, but experts say it could still sneak into small, backyard orchards.

Plum pox virus can devastate entire peach orchards, said Phil Brannen, an Extension Service plant pathologist with the University of Georgia College of Agricultural and Environmental Sciences.

Infected trees produce unsweet, blemished fruit that can't be sold. And once a tree is infected, there is no cure.

To keep the disease from spreading when an infected tree is identified, Brannen said, you have to destroy every tree within a 500-meter.

"If several trees were to be infected in an orchard, the total production of that orchard could be wiped out," he said.

Photo:USDA

Peach trees infected with Plum Pox virus produce fruit that is misshapen and discolored.

The disease isn't harmful to humans. But a disease like plum pox would be poison to Georgia's $24 million annual peach crop.

Preventive Measures

A UGA CAES peach team of horticulturists, plant pathologists and entomologists began an aggressive survey last year to keep the disease out of Georgia orchards.

It's not in the state's commercial orchards now, Brannen said. But the disease could find its way in through the small numbers of trees people plant in their backyards.

"People buying peach trees for home or small orchards need to be careful where they get the trees," Brannen said. "They shouldn't bring in budwood from outside the state."

Budwood cuttings are branches taken from a desirable tree variety. The buds from these branches are grafted onto other trees to produce seedlings.

In general, the tree material sold in Georgia is safe, he said.

In peaches, an infected tree produces white ring spots on the leaves and fruit. But it could take years before an infected tree shows signs of the disease, he said.

Photo:USDA

Plum Pox virus causes peach trees to produce unsweet fruit, which would make Georgia's peach crop worthless.

Plum pox can be carried short distances by small insects known as aphids. But for long-distance travel, the disease needs human intervention, Brannen said.

It Could Happen

Plum pox virus has caused disease in peaches and other stone fruits, such as plums and nectarines, in Europe since 1915. But it hadn't been identified in the United States until the fall of 1999, Brannen said.

That year, the disease was confirmed in Pennsylvania orchards. More than 1,000 acres of peaches and nectarines have been destroyed in hopes of containing the virus there.

But the virus was recently found in Canada, where it has caused extensive damage to the peach industry.

No one knows for sure how the disease made its way into the United States. But more than likely, Brannen said, someone brought tree material into the country.

"If we get it (plum pox), it's going to be really hard to control," he said. "If we get to that point, we would have to live with it. And the cost of production would be huge for Georgia's peach industry."

Brannen said it would be hard for Georgia growers to competitively produce peaches with plum pox. "We're trying to make sure we don't have that same situation in Georgia," he said.

So far, the 2001 Georgia peach harvest is off to a good start. The Georgia Agricultural Statistics Service reports that 93 percent of the peach crop is in good to excellent condition.

As of May 27, about 11 percent of the peaches were harvested.