An adult Asian citrus psyllid has been found in a trap in a commercial citrus grove in early June - the first time ever in California.

The discovery is not the first psyllid found in San Luis Obispo County, but marks the first time the dangerous pest has been found in commercial citrus, according to Martin Settevendemie, agricultural commissioner in San Luis Obispo County.

Settevendemie said the grower and his pest control advisor (PCA) were cooperative with agricultural officials and immediately completed an eradication treatment in response to the find. The treatment includes targeted chemical applications on citrus within 800 meters, or roughly one-half mile.

The find was in a conventional citrus grove, Settevendemie said.

The area where the trap find was made has three citrus groves. Agricultural officials are working with other growers in the area to inform about the find and work to find treatment options to move the fruit.

The bulk of San Luis Obispo County’s commercial citrus, which is in the Nipomo area, is not under quarantine at this time because of where this and previous finds were made. Other county finds are in the cities of Cayucos (northern county), San Luis Obispo (central part of the county) and in Arroyo Grande (southern portion).

According to the 2014 crop report, San Luis Obispo County has about 250 acres of Valencia oranges and over 1,600 acres of lemons.

Officials warn growers and homeowners to inspect citrus trees for signs of the ACP, particularly as trees are developing new flush, which is particularly attractive to the ACP. The pest will feed and lay its eggs in this new flush or growth on the trees.

Since the insect is so small (about the size of a pencil lead), it takes a trained eye and a hand lens to inspect for the pest, particularly for evidence of unhatched nymphs.

The ACP can vector a disease called Huanglongbing (HLB), which is deadly to citrus trees. One confirmed case of HLB was reported in suburban Los Angeles in 2012. The disease is present in Mexico and is widespread in Florida.

Information on the disease and its symptoms can be found online.

Commercial citrus growers considering pesticide treatments in their groves are urged to consider including ACP-active materials in upcoming grove treatments. University of California pest management guidelines, including a list of broad-spectrum foliar insecticides for the ACP, are available online.

As of July 1, the use of Chlorpyrifos is labeled “restricted-use” by the California Department of Pesticide Regulations. It is also included in separate regulations pertaining to the use of low-VOC compounds in the San Joaquin Valley.

Review the label instructions before using the product.