Public urged: Be careful with citrus trees

With a dramatic increase in the number of Asian citrus psyllid detected in western Arizona, including Yuma County, the Arizona Department of Agriculture has updated the quarantine that limits the movement of citrus plants.

The agency already had a quarantine in place for the southwestern portion of Yuma County. The new quarantine adds a 20-mile area around Lake Havasu City, from about 10 miles north of Interstate 40, south to the Avi Suquilla Airport (north of Parker in La Paz County) and all areas west of Alamo Road.

Asian citrus psyllid, an insect no bigger than a grain of rice, is a threat because it can carry citrus greening disease, otherwise known as huanglongbing (HLB).

Citrus greening is the most devastating disease known to infect citrus trees, according to Laura Oxley, spokeswoman for the Arizona Department of Health Services.

There is no known cure. Once a tree is infected, it will die, she noted.

When the Arizona Department of Agriculture first detected the Asian citrus psyllid in San Luis, Ariz., in October 2009, the agency feared it would destroy homeowners' citrus trees and the citrus fruit and nursery stock industries, which add at least $37 million each year to the state's economy.

However, it quickly halted the spread of the pest by establishing a quarantine and control measures.

Since then, the agency and partners have maintained a statewide trapping program. Until January, only single adults of Asian citrus psyllid were found in 17 locations with no repeat detections at any of those sites.

But multiple detections in the Lake Havasu City area prompted the state to update the quarantine boundaries.

And the department is asking for the public's help in controlling the spread of the pest by buying only inspected, certified citrus nursery stock for home planting.

The agency also requests that personal citrus plants, including grafting material, or homegrown citrus fruit not be moved without certification from a state regulatory official.

If homeowners have citrus trees, they should check for the presence of the psyllid, which typically lay eggs during the fall and winter months. If found, the homeowner should call the Arizona Department of Agriculture. (See below for identifying characteristics of the pest.)

HLB is a bacterial disease that attacks the vascular system of plants. It does not pose a threat to humans or animals.

Infected Asian citrus psyllid spread the bacteria causing the disease as they feed on citrus trees and other plants. The insect leaves white threads on the tips of new leaves.

The disease threatens Arizona and California's $2.2 billion lemon industry. Arizona is the second-leading state in the U.S. for lemons and third for tangerines, much of that produced in Yuma County, according to the 2010 Arizona Agricultural Statistics.

In 2009, lemons were grown on 7,155 acres in Yuma County for a value of nearly $19 million.

For more information on Arizona's quarantine and ACP work, visit www.azda.gov/psd/acp.htm. For more information on citrus health issues, go to www.saveourcitrus.org.

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What does the Asian citrus psyllid look like?

Adults:

• 3-4 mm (0.12-0.16 in.) in length

• Mottled, yellowish-brown body with brown legs and a light brown head. The underside (ventral part) of the body is greenish-white.

• Abdomen of females turns bright yellow-orange when ready to lay eggs (gravid).

• Transparent wings with white spots, or light-brown with a central beige band. Forewings widest near tip.

• Very short antennae (0.48 mm or 0.019 in.), eight yellow segments, two terminal black segments, and two short hairs at the tip.

• Appears dusty due to a whitish, waxy secretion.

Immatures:

• Five nymphal instars.

• 0.25 mm-1.7 mm (0.01-0.07 in.) in length.

• Light yellow to dark brown.

• Red eyes.

• Well-developed, large wing pads.

Eggs:

• Approximately 0.01-0.15 mm (less than 0.005 in.).

• Bright yellow-orange.

• Almond-shaped, thicker at the base, and taper toward the opposite end.

— Source: idtools.org