Search

Phytoseiid mites are key predators in agricultural crops. However, not all species regulate pest populations below economic thresholds, and therefore knowledge of which species are associated with particular crops aids pest control recommendations. Surveys of 12 crops across six geographical regions of California demonstrated that phytoseiid species varied by crop and geographical location, with subtropical crops exhibiting the lowest species diversity and grape the greatest. The western predatory mite, Galendromus occidentalis, long cited as a dominant species in California crops, was not found to be the major species in most situations. Euseius stipulatus, a species introduced in the 1970s, was found in the surveyed crops in many areas of the state and appears to be displacing E. hibisci along the south coast.

Efforts to exclude disease organisms from farms growing irrigated lettuce and leafy vegetables on California’s central coast are conflicting with traditionally accepted strategies to protect surface water and environmental quality. The agricultural community, scientists and producers, are caught between the requirements to safeguard water quality and efforts to ensure a safe food supply. These programs evolved independently, albeit side-by-side, leading to separate habits of thought among environmental and food safety scientists in academia, business, and non-profit programs. The potential for coordinated management of water quality and food safety on-farm management practices was the focus of a conference held in San Luis Obispo, California in April 2007. Conference presentations, discussions, farm visits, and working groups used existing technical guidance to frame research and organizational objectives. These conference products were summarized for inclusion in iterative on-line questionnaires, with conference attendees participating as respondents. This process, called a Delphi process, produced general research priorities in coordinated management. Conference participants, who self identified as having either food safety or water quality as their primary area of focus, prioritized research objectives under theme areas. There were general research objectives, which approached consensus by the whole group, including: 1) persistence and fate of pathogen in the crop and in conservation practices; 2) pathways by which pathogens move through the crop production system; and 3) identification of environmental conditions that promote pathogen survival and proliferation. Conference participants and Delphi respondents were not able to identify an existing forum for gathering and disseminating coordinated management information. Respondents placed their highest priority on the formation of a Coordinating Council, and identified those entities that ought to play specific roles within the Council. Two technical guidance documents, one emphasizing on-farm management of food safety and one stressing water quality practices, are already in use by a majority of leafy greens growers on California’s Central Coast. Used together, these technical guidance documents can be used to develop an initial framework for the evaluation and development of coordinated management practices that protect both human health and the environment. The conference final report and accompanying materials are published online at http://groups.ucanr.org/wqfsconf/.

The red gum lerp psyllid is an insect native to Australia, where it feeds upon eucalyptus species. Since 1998 this psyllid has spread throughout California, resulting in millions of dollars in damage and control costs. To help suppress the red gum lerp psyllid, a biological control program was initiated and a psyllid-specific parasitic wasp was imported from Australia in 1999 and released in 2000. In most coastal regions this biological control agent has provided substantial control, but in some interior regions the psyllid still remains a problem. Researchers are continuing their investigations to determine if full statewide suppression will be realized eventually, or if further importation of new parasitoid species is needed.