Using digital imaging techniques, entomologists
identify morphological variations used to identify mite species that spread
citrus leprosis. Click the image for more information about
story to find out more.
On the Lookout for Mite-Borne Citrus
Threat By Luis
March 11, 2004
A mite-borne plant disease moving slowly north from South
America is on the radar screen of many scientists, including those at the
Agricultural Research Service's
Systematic Entomology Laboratory (SEL) in Beltsville,
They're concerned that citrus leprosis, a virus that
substantially damaged Florida's orange crop early last century, will once again
affect U.S. citrus growers. They're out to stop it by focusing on its vector:
flat mites of the genus Brevipalpus.
SEL's mite expert, entomologist Ronald Ochoa, says the disease's
presence in Central America has caught the attention of U.S. Department of
Agriculture scientists at ARS and at the Animal and Plant Health Inspection
Service (APHIS). ARS is the
USDA's chief scientific research agency.
Mite species believed to be capable of spreading the disease are
already abundant in Florida, California and Texas, three states that are the
backbone of the U.S. citrus industry. SEL scientists are collaborating with the
Florida Department of Agriculture and
Consumer Services to clarify differences among the Brevipalpus
species implicated as leprosis vectors. This work is part of a wider
project--funded in part by USDA's Foreign
Agricultural Service and APHIS, and led by University of Florida acarologist Carl C.
Childers--seeking to minimize the virus's impact.
Symptoms of citrus leprosis include small, chestnut-brown spots
commonly referred to as "nailhead rust" that appear on fruits, leaves and green
twigs of afflicted trees. The resulting tree canopy growth loss and premature
fruit and leaf drop reduce plant productivity.
During its previous outbreak, the virus had spread to 17 Florida
counties by 1925 before being eradicated by several factors, including citrus
growers planting in new locations and controlling mites with sulfur. The
overuse of sulfur can kill citrus trees.
about this research in the March issue of Agricultural Research