Brief Summary of Minutes of Annual Meeting

Introductions were made. The agenda was discussed. Steve Loring explained the purpose of the W1007, how regional coordinating committees work and how a person can join. Participants that have not officially joined are encouraged to contact their experiment station or extension directors. The mid year report was presented and there was a discussion of the pros and cons of becoming a regional project versus a coordinating committee. Reports on curly top in western states were given by several individuals. Rebecca Creamer gave an overview of curtoviruses in New Mexico and discussed research on the curly top isolates infecting chile and weeds in the state. The distribution of the viral species, BSCTV, BMCTV, PeYDV, and pepper curly top virus have varied since 2001. New viral species occur through recombination. Claudia Nischwitz discussed an outbreak of curly top in spinach in Arizona. The plants showed characteristic symptoms. They were positive for curtoviruses by PCR, as were nearby weeds, London rocket and Chenopodium. Sequencing showed the plants to be infected with pepper curly top virus (98% identity). Graeme Davis presented an ecological study on the leafhopper vector of curotviruses, Neoaliturus tenellus (Baker), which is a change in genus for the leafhopper. Leafhoppers were monitored by sweep net and beat bucket for the last two years in southern New Mexico. The leafhoppers were separated by age and the plants were assessed for eggs. All nympal stages, eggs, and adults were collected primarily from London rocket and Kochia. The leafhopper appears to have extended generations from March through July and another generation in the fall. The ratio of males to females changed around April 1, with a large increase in the proportion of males. Rebecca Creamer presented a comparison of the beet leafhopper in California to that in New Mexico. Stylet track staining was done to compare overall preferences. While the leafhoppers are morphologically identical, they differ in feeding preference and mt coi sequence, while leafhoppers within New Mexico were similar. Robert Call reported that curly top pressure was very low in Arizona, particularly in chile and tomato. Pinto beans were reported infected at a in a single field. Mary Olsen reported infection in Arizona in leafy greens. Bob Hammon sent his report on Colorado. He said that curly top rates were relatively low in western Colorado in tomatoes during 2009, with losses less than 10% and many growers experiencing only 1-2% loss. An occasional commercial Kabocha squash field was also found infected. He compared reflective plastic mulch to red mulch in drip irrigated plots. Insect counts were highest on red mulch early in the season, but generally leafhopper counts were low all season. In comparison, thrips numbers were very high. The final results from the 2009 research will be posted at http://wci.colostate.edu by mid October. The California report was sent via email from Rod Clark, CDFA. He explained that the state Beet Curly Top Virus Control Program in California was re-initiated, but with severe budget cuts due to the poor state economy. They obtained a permit and treated beet leafhopper populations during spring 2009. The infection rate in tomatoes was dramatically reduced as compared to the spring 2008 when as estimate $20,000,000 damage resulted from the inability to treat rangeland. They collected plant and leafhopper samples which were processed at UC Davis by Dr. Robert Gilbertsons lab. So far, more BMCTV has been found than BSCTV in both plant and leafhopper samples. Tomato spotted wilt virus has been an increasing problem and symptoms in tomatoes can easily be confused with those caused by curly top. Stephanie Walker sent her report on curly top in New Mexico. Curly top incidence was very low in chile. A larger concern was infection of chile with alfala mosaic and tomato spotted wilt viruses. Phil Miklas sent the report from Washington. He said that curly top pressure was very low during the last year (below average), based on reduced incidence in his bean plots, and other crops such as pumpkin. Stephanie Walker and Ed Curry sent brief comments as to their attempts to use sugarbeets as trap crops for chile. Both state that they had mixed results and would need additional tests. Practical questions and comments for curly top management were raised by the extension personnel. Will trap crops work for a variety of different crops at different locations? When is the optimal time to control weeds to reduce disease? Which weeds should be controlled? Can another leafhopper be introduced to replace the beet leafhopper in the same weed ecosystem? Can we add something to the xylem to deter the leafhopper from feeding on crops? There is a need for better diagnostics for curly top in various crop hosts. There is a need for resistance/tolerance in spinach and other leafy greens. There was a brief discussion as to the 2010 meeting, with ideas for locations. One suggestion was to hold the meeting in western Colorado, so that participants could view the ongoing mulch trials.

A collaborative project for 2010 was established at the meeting between Rebecca Creamer, Mary Olsen, and Claudia Nischwitz.

Stafford, C. A., Walker, G. P., Creamer, R. 2009. Stylet penetration behaviour resulting in inoculation of beet severe curly top virus by beet leafhopper, Circulifer tenellus. Entomologia Experimentalis et Applicata 130:130-137. Wintermantel, William. 2009. Beet curly top virus. Pages 51-53 in: Compendium of Beet Diseases and Pests, 2nd ed. RM Harveson and LE Hanson, eds., APS Press, St. Paul, MN. Wintermantel, William. 2009. Resistance to curly top viruses through virus induced gene silencing. Proceedings of the 35th Biennial Mtg American Society of Sugar Beet Technologists. Miklas, P. N., Seo, Y.-S., Gilbertson, R. L. 2009. Quantitative resistance to bean dwarf mosaic virus in common bean is associated with the Bct gene for resistance to beet curly top virus. Plant Disease 93:645-648. Lam, N., Creamer, R., Rascon, J., and Belfon, R. 2009. Characterization of a new curtovirus, Pepper yellow dwarf virus, from chile pepper and distribution in weed hosts in New Mexico. Archives of Virology 154:429-436. Stafford, C. A., Walker, G. P., and Stafford, C. A. 2009. Characterization and correlation of DC electrical penetration graph waveforms with feeding behavior of beet leafhopper, Circulifer tenellus. Entomologia Experimentalis et Applicata 130:113-129. Chen, L,-F. and Gilbertson, R. 2009. Curtovirus-cucurbit interaction: acquisition host plays a role in leafhopper transmission in a host-dependent manner. Phytopathology 99:101-108.