tions for nurseries in the quarantine area that are free of DRW to be $300 per acre. The additional cost for a nursery infested with DRW was an estimated $225 per acre and the total cost to meet quarantine regulations was $525 per acre. At present, nurseries free of DRW but within the quarantine area are required to incorporate the granular insecticide bifenthrin into the soil before plants are potted. The granular treatment is good for 2 years, the growers are then required to use a soil drench every 6 months thereafter. For nurseries with infestations, an additional foliar spray treatment with carbaryl would be required. The per acre cost for the foliar spray treatment was provided by the industry and was estimated to be $599 to $625 an acre. Because only a portion of the total acreage would need to be treated the estimates of the total per acre costs to the nursery industry were calculated assuming that 10% of all acreage had infestations. Applying the percentage decrease in revenues per acre to the total gross revenues for nursery crops required to meet quarantine regulations, the annual losses are estimated to be $1.05 million for the floriculture industry and $4.37 million for other nursery industries. Total annual losses are estimated to be $5.42 million. Conclusion: There was a considerable delay between the time of the initial infestation and when eradication efforts (pesticide treatments) began. The slow response to the invasion most likely allowed considerable Diaprepes dispersal during the time it took the CDFA to develop a treatment protocol. There was also considerable time between the draft nursery treatment protocol and an official protocol. These results demonstrate the need for proactive protocol development so that delays in action do not occur. A noteworthy success in the Diaprepes Project was the cooperation among the nursery industry representatives and CDFA. The nursery industry organized a tour for CDFA policy makers to demonstrate the great diversity of production and plant types in the ornamental production industry. The tours also demonstrated that there could not be a one-size-fits-all approach to protocol development for this industry, while the collaborative involvement of nursery, university, and regulatory personnel helped identify areas of research and funding needed to support the approved treatment protocols. Glassy-winged Sharpshooter – Homalodisca vitripennis (formerly H. coagulata) The glassy-winged sharpshooter (GWSS) probably first entered California as eggs deposited into plant tissues of agricultural plants. GWSS was first collected near Irvine in 1989 but not recognized as a newly introduced species
38 December 2010
until later. The leafhopper was identified by the California Department of Food and Agriculture as a species common in the southeastern states from Florida through eastern Texas and as far north as Missouri. GWSS is considered the prime vector of the bacterium Xylella fastidiosa to peach and grape in Georgia, Florida, and other southern states. GWSS has been seen in high numbers in citrus along the coast of southern California since the early 1990s. During the past few years it has become locally abundant further inland in Riverside and San Diego counties. In 1998 and 1999 high populations on citrus and adjacent vineyards were seen in southern Kern County. In August 1999 after GWSS-spread Pierces Disease had devastated several grape vineyards in Temecula, California, the CDFA preliminary field survey showed GWSS present in eight southern California counties and the CDFA GWSS/PD Task Force was formed. Due to the threat of disease spread, the GWSS was changed from a “C” rated pest (an organism subject to no state-enforced action except to provide for pest cleanliness in nurseries) to a “B” rated pest (an organism of known economic importance subject to: eradication, containment, control or other holding action at the discretion of the individual county agricultural commissioner). GWSS is an insect pest that attacks urban, nursery, agricultural, and native trees and shrubs. Several mutations of Xylella fastidiosa have developed which will mean costly losses to a wider variety of crops and urban landscapes. Native riparian, urban, and agricultural plantings are now potential reservoirs of GWSS and Xylella spp. that can potentially affect their neighbors. Time Line of Key Developments • In 2001, Assembly Bill 1394 was signed; bolstering research and other program activities by providing funding and the Pierce’s disease and Glassy-winged Sharpshooter Board was established to administer the funds. • In 2002 new emergency program regulations were filed and an area-wide GWSS management program was implemented in Ventura County; the area wide control program in Kern County was expanded. • In 2003, permanent program regulations governing the movement of nursery stock, bulk grapes and bulk citrus were adopted and the Coachella Valley Area-wide GWSS Program was begun. Experiments to test the efficacy of pre-shipment treatment of nursery stock at killing GWSS eggs masses were conducted as part of the program to help California nurseries with their efforts at keeping nursery stock shipments free of GWSS.
December CAPCA Adviser