Report for June/July 2016
Courtesy UC Davis
Program-wide notice
- The Beet Curly Top Virus Control Program (BCTVCP) began conducting fallow field and beet leafhopper (BLH) population surveys after ground rig treatment was completed in June.
- The Program began mapping fallow fields that had good coverage of fall host plants, such as Russian thistle and goosefoot. Preparations to send out treatment waivers will take place in August.
- The widespread nature of fall host plants permits the BLH to scatter, making it difficult to observe high counts in sweep surveys. BLH populations at the end of July were low throughout the San Joaquin Valley. As property owners begin to receive treatment waivers, many fallow fields will be disked or grazed. This reduction in host plant acreage concentrates BLH on the remaining host plants, increasing counts and allows for better control during the fall treatment campaign.
Fresno County
- Program personnel monitored roadside host vegetation and fallow fields for BLH populations and fall host plants in Firebaugh, Mendota, Huron, Five Points, Three Rocks, Cantua Creek, and Coalinga.
- Fallow fields were identified and mapped from Highway 198 in Fresno County, working north to Kamm Avenue and from Kamm Avenue north to the Merced County line. The predominant host plants were Russian thistle, Bassia, goosefoot, and lambsquarter.
- BLH counts were low, with an average of 0-2 BLH per sweep. Counts typically increase as fallow fields are disked or grazed. Program personnel observed high concentrations of aphids and thrips during surveys.
- Approximately, 20,000 acres in Fresno County have been mapped for potential fall treatment. Acreage will be adjusted as fields are disked, grazed, and as BLH populations concentrate. Waivers will be sent in early August.
- Twenty four (24) symptomatic tomato plant samples were collected and sent to the lab for virus analysis in June and July. Eighteen (18) were positive for curly top virus.
Imperial County
- BLH and host plant vegetation surveys were conducted the week of May 23, 2016.
- Three (3) host plant samples were obtained and sent for virus analysis. All three samples were positive for curly top virus.
- Three (3) BLH samples were collected and sent for virus analysis. All three samples were positive for curly top virus.
Kern County
- Program personnel monitored roadside host vegetation and fallow fields for BLH populations and fall host plants.
- Fallow fields were identified and mapped with the majority of the fields detected in the Lost Hills/Devil’s Den area of Kern County. The predominant host plants were Russian thistle and Bassia.
- BLH counts were low. Counts typically increase as fallow fields are disked or grazed.
- Approximately, 40,000 acres have been mapped for potential fall treatment. Acreage will be adjusted as fields are disked, grazed, and as BLH populations concentrate. Waivers will be sent in early August.
- Two (2) sorghum plant samples were collected and sent for virus analysis. Both were positive for curly top virus.
- Thirteen (13) symptomatic tomato plant samples were collected and sent to the lab for virus analysis. Six (6) tested positive for curly top virus and two (2) were positive for tomato spotted wilt virus.
- One (1) BLH sample was collected and sent for virus analysis. It was positive for curly top virus.
Kings County
- Program personnel monitored roadside host vegetation and fallow fields for BLH populations and fall host plants.
- Fallow fields were identified and mapped with the majority of the fields detected southeast of Kettleman City and east of Interstate 5 and Utica Avenue. The predominant host plants were Russian thistle and Bassia.
- BLH counts were low. Counts typically increase as fallow fields are disked or grazed.
- Approximately, 12,000 acres in Kings County have been mapped for potential fall treatment. Acreage will be adjusted as fields are disked, grazed, and as BLH populations concentrate. Waivers will be sent in early August.
- Twelve (12) symptomatic tomato plant samples were collected and sent for virus analysis in June. Eight (8) were positive for curly top virus.
Merced County
- BLH population surveys, host plant vegetation surveys, and fallow field surveys were conducted. BLH counts were low with an average of 0-2 adult BLH per sweep. In one fallow field near Ward Road south of Phillips Road, BLH counts were higher, with 4-5 adults and 5-6 nymphs per sweep. The host plants in that field were purslane, goosefoot, and some Bassia.
- Tomatoes where surveys were conducted appeared to be in good condition.
- Eleven (11) symptomatic tomato plant samples were collected and sent for virus analysis. Six (6) were positive for curly top virus.
- Seven (7) BLH samples were collected and sent for virus analysis. Six (6) were positive for curly top virus.
- Personnel will continue to monitor BLH populations and collect both host plant and BLH samples for virus analysis.
Monterey County
- Surveys were conducted the week of May 23, 2016 in Salinas Valley.
- Two (2) host plant samples were collected and sent to the lab for virus analysis. One (1) sample tested positive for curly top virus.
- Two (2) BLH samples were collected and sent to the lab for virus analysis. Both samples were positive for curly top virus.
Riverside County
- BLH and host plant vegetation surveys were conducted the week of May 23, 2016.
- Four (4) host plants samples were collected and sent for virus analysis. All four samples were positive for curly top virus.
- Four (4) BLH samples were collected and sent for virus analysis. All four samples were positive for curly top virus.
Sacramento Valley
- Program personnel conducted surveys the week of June 13th. Roadside vegetation and tomato fields were surveyed. There were very few BLH observed during the week.
- Surveys began in the northern portion of Sacramento Valley, in Glenn and Butte Counties, where the tomato fields were limited, but increased near the Colusa County border. Tomato fields looked good with minimal damage. There were no BLH observed during surveys.
- Surveys were conducted in Sutter and Colusa Counties. Tomato fields appeared to be in good condition. There was more roadside vegetation but only 1 adult BLH was observed during surveys that day.
- Surveys continued in Sutter and Colusa Counties, working through Yolo County as well. There was a significant increase in host plants that included Russian thistle and Bassia. A total of seven adult BLH were observed during surveys. Tomatoes in the area appeared to be in good condition.
- Surveys were conducted in Sacramento County between Woodland and Sacramento. Tomato fields were limited, but appeated to be in good condition. No BLH were observed during surveys.
- Eleven (11) host plants were collected and sent to the lab for virus analysis. All samples were negative for curly top virus.
- Four (4) symptomatic tomato plant samples were collected and sent for virus analysis. All samples were negative for curly top virus.
San Joaquin County
- BLH population surveys, host plant vegetation surveys, and fallow field surveys were conducted. BLH counts were low with an average of 0-2 adult BLH per sweep.
- Two (2) symptomatic tomato plant samples were collected and sent for virus analysis. One (1) was positive for curly top virus.
- Two (2) BLH samples were obtained and sent for virus analysis. Both samples were positive for curly top virus.
- Personnel will continue to monitor BLH populations and collect both host plant and BLH samples for virus analysis.
Stanislaus County
- BLH population surveys, host plant vegetation surveys, and fallow field surveys were conducted. BLH counts were low with an average of 0-2 adult BLH per sweep. In a couple of areas with purslane, BLH counts were higher, with 3-4 adult BLH per sweep.
- One (1) host plant sample was obtained and sent for virus analysis. It was negative for curly top virus.
- Four (4) symptomatic tomato plant samples were collected and sent for virus analysis. All four were positive for curly top virus.
- Five (5) BLH samples were collected and sent for virus analysis. Three (3) were positive for curly top virus.
- Personnel will continue to monitor BLH populations and collect both host plant and BLH samples for virus analysis.