By Vicky Boyd

The U.S. Department of Agriculture has confirmed what was suspected of being citrus black spot in Florida is indeed that disease.

Earlier, two University of Florida researchers had conducted independent tests, and both identified the disease as citrus black spot. But a disease find isn't considered official until USDA tests confirm its identity.

The Division of Plant Industry collected a suspicious sample from a commercial valencia orange grove near Immokalee in Collier County on March 8.

The sample was collected as part of a routine Citrus Health Response Program inspection requested by the grove owner.

The USDA has issued emergency action notices for five groves near the find, says Nolan Lemon, a public information officer with the department's Animal and Plant Health Inspection Service in Raleigh, N.C. The notices essentially quarantine the operations.

The notices require hand picking of the fruit, tarping of all fruit trailers, and proper sanitation of all equipment and personnel leaving the groves, among other items.

All of the fruit is destined for processors, who also will be required to clean and sanitize trailers and to properly dispose of the rind and other plant material, Lemon says.

DPI and USDA inspectors are conducting delimiting surveys around the initial find. So far, they've checked groves within a 7-mile radius, he says.

A risk analysis will need to be conducted before any rule making for a quarantine is started, Lemon says.

The USDA did notify the nation's trading partners of the find before issuing the press release.

"The biggest thing is we are working with our trading partners to ensure that these markets will remain open," he says.

The European Union, for example, will not accept fruit from an area, such as South Africa, with black spot.

The department will continue to keep foreign trading partners as well as officials in citrus-producing states abreast of happenings, Lemon says.

Joel Nelsen, president of Exeter, Calif.-based California Citrus Mutual, says his state's growers are definitely concerned about the find in Florida.

"The one thing in our favor is that the [Florida] fresh fruit season is winding down in the next couple of weeks, and the detection was extremely far removed from any fresh fruit production that is making it's way into the market," he says. "I think our vulnerability is extremely limited this season. However, we've told the USDA and we have talked to our colleagues in Florida that moving fresh fruit from a black-spot infected area to any state is a non-starter."

As its name implies, the fungal disease causes black spots on the citrus peel, rendering it unmarketable.

In severe cases and if the disease goes untreated, it can cause severe premature fruit drop. It is caused by the fungus Guignardia citricarpa.

Lemons and late-season oranges are more vulnerable, although most cultivars are suspceptible to the disease.

It can be controlled with many of the same products used for citrus canker.

For more information on citrus black spot, click here for the University of Florida EDIS publication.