Brief Summary of Minutes of Annual Meeting

NRSP-005 is a national program committed to minimize the adverse effects of viruses in orchards of the United States by providing virus-free propagation material of important temperate tree fruit varieties from domestic and foreign sources through traditional and innovative methods of virus testing and therapy, and by forging collaborative relationships with government agencies, universities and industry to help maintain U.S. agricultural productivity, market competitiveness, balance of trade, and a diverse, wholesome and affordable food supply. Virus detection: A Shiro plum clone was discovered that is more sensitive to American plum line pattern virus than the standard clones used for years by NRSP-005 and other quarantine programs (USDA-APHIS, CFIA). The standard clone of Shiro plum is a marginal indicator for this virus in the greenhouse and often only a mild yellowing occurs on the leaf tip margin. There are currently no alternative testing procedures for this virus that have been validated. However, this new selection shows extensive venial net chlorosis and line patterns when inoculated with virus. This new virus indicator will continue to be evaluated by this and other programs for its utility as a greatly improved virus indicator plant. Virus sensitivity screening: NRSP-005 continues to evaluate the sensitivity of new potential cherry rootstocks for severe hypersensitive reactions to common viruses. Candidate clones 'VSL2' and 'LC52' are of Russian origin, and died in the presence of either of the two common pollen-transmitted cherry viruses. Sweet cherry trees on 'L2' rootstock from the same breeding program or on mazzard rootstock were tolerant of the viruses in this test. Distribution of virus-tested budwood: NRSP-005 provided over 500 virus-tested varieties to research and industry from July 1, 2005 to April 1, 2006. These included 25,000 buds of proprietary, non-proprietary and foreign clones bringing the total distribution over the past 20 years to 630,000 buds in response to 2,400 requests. In the past year, budwood was distributed to over 80 clients located throughout the country and internationally. They represent universities, nurseries, fruit growers and government regulatory agencies. Thousands of the virus-negative buds were provided to establish foundation material in certification programs for subsequent distribution to orchards throughout the country. Distribution from the virus collection: Beyond the distributions for fruit production, many other types of tissue were distributed to scientists for research purposes. Virus-infected fruit, leaves, seed, flowers, seedlings, pollen and trees were sent to scientists at land-grant universities and government regulatory and research agencies. New clone acquisitions: In the last season, 79 stone and pome fruit cultivars were submitted to NRSP-005 for virus testing and virus elimination. These numbers are significantly lower than in past years, likely as a result of the doubling of service fees charged for these services. The largest proportion of the introductions was from foreign sources. Varieties were submitted for testing only as part of the on-going qualification program for certification in California. Approximately one-third of the clones submitted to the program in the last two years were infected with virus, viroids, phytoplasma and/or Xylella.

A book chapter has been prepared for publication in 2006 by Guerra and Eastwell describing phytoplasma diseases of temperate fruit crops and their detection.