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Nurserymen on alert for new pests

Diaprepes has finally made it into Southern California nurseries. The protocol being developed by the CDFA in Sacramento is not quite complete, but it’s what we have to work with. CDFA is under a mandate to act in the quarantine, but they also are aware of the industry’s need to continue to do.

There are three pest stages that are critical with respect to eradication, and there are three pesticides that you should be aware of, Sevin (carbaryl) for adults, Dimilin/Adept, (diflubenzuron) for eggs, and Talstar (bifenthrin) for the soil borne larval stage. There is also a predatory nematode that will be important during treatment of long term crops, but the availability and the efficacy is still in question.

The protocol is tailored for the diversity of the industry, so that every plant and pot type in the industry is covered.

A second pest that will have an impact on the ornamental industry is, the Asian Citrus Psyllid. The insect is an efficient vector of Citrus Greening, a phloem-limiting bacterium that was detected for the first time in the U.S. in Florida last year.

Citrus Greening is one of the most serious diseases in the world on citrus. In countries where the disease is endemic, the life span of trees is reduced from 50 to 15 years. In addition, infected trees live only three to five years before death. There is no known cure for the disease. Infected tree removal is the only solution.

The Asian Citrus Psyllid was recently discovered to be well-established in Mexico. We are surrounded, and the citrus industry has been preparing for the invasion.

The Asian Citrus psyllid was first detected in Florida in 1998 and spread rapidly via nursery stock (orange jasmine) to 30 counties by 2001. In addition, they were shipped to Texas via nursery stock (Orange Jasmine) in 2001 as well. USDA/APHIS immediately ordered the halt of all shipments of citrus and citrus related hosts (ornamentals) from Florida to California and other citrus growing states.

The citrus industry in California will act just as the grape industry during the Pierces Disease crisis and the glassy-winged sharpshooter. The citrus industry has already set a long-term goal to strengthen the exclusion programs of ornamental plant material.

Another new Southern California pest, Japanese dodder (Cuscuta japonica) has been introduced into California and nurserymen and other producers should be watching for it in the nursery, greenhouse, and surrounding areas. Japanese dodder is an annual, parasitic vine that has is commonly used by Asian cultures as an herbal remedy.

CDFA considers it a “Q” rated noxious plant, and it is listed as a Federal noxious weed. The dodder itself looks very similar to a thick diameter spaghetti noodle that is bright yellow-orange. It parasitizes host plants by penetrating the vascular tissues with structures called haustoria, and severe infestations can completely engulf host plants draping to the ground potentially killing the host plant. Japanese dodder was found for the first time in California in the summer of 2004 in Redding and in Yuba County in 2005. It is native to Asia and there are infestations in Texas, Florida, and South Carolina.

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