Wasps released to fight N. County citrus pests

Tiny, parasitic wasps are being released in North County to fight the spread of a deadly citrus disease carried by an insect called the Asian citrus psyllid.

Psyllids carry the disease, called Huanglongbing (HLB), from tree to tree as they feed on the leaves. The wasp, called Tamarixia raidata, is a natural predator of the psyllids and reduces their population, according to an announcement from the California Department of Food and Agriculture.

Pesticides also are being used, according to state officials. Licensed applicators are treating trees where the psyllids have been observed with a combination of the foliar spray Tempo and a root drench of the systemic Merit. Foliar sprays work best when leaves are new, and root treatments are best in summer and fall.

Homeowners can use the foliar pesticides Sevin and Malathion. Other options include horticultural oils and insecticidal soaps, but these products are short-lived and must make direct contact with the insects, so they must be applied more frequently.

The first sign of the disease in San Diego County was discovered in August in two trees on residential property in Oceanside, leading to a 60-square-mile quarantine of citrus fruit, plant parts and nursery stock.

The quarantine area extends from Vandegrift Boulevard on Camp Pendleton south to Carlsbad Village Drive, and from the Pacific Ocean east to Melrose Drive.

While the disease is relatively new to San Diego County, it has been confirmed in more than 2,400 residential trees in five Southern California counties with the majority in Orange County. Trees that have the disease, also called citrus greening, cannot be cured and must be carefully removed to prevent its spread.

California agricultural officials say the disease is a major threat to the state’s citrus industry.

HLB originated in China. It was first found in Florida in 1998, where since then it has killed off entire orchards and decimated the state’s $9 billion citrus industry. Thousands of Florida growers have dropped out of the citrus business, according to news stories. Those that remain are spending 50 percent more each year on preventing the disease.