Location: Horticultural Crops Disease and Pest Management Research Unit
Project Number: 2072-22000-044-010-G
Project Type: Grant
Start Date: Aug 1, 2020
End Date: Dec 31, 2022
Objective:
1. Refine determinants of risk of Rose Stem Girdler (RSG) damage to Pacific Northwest (PNW) caneberry plantings.
2. Develop an enhanced integrated pest management (IPM) program via refined information on the life cycle (phenology) of RSG in the PNW and development of a phenology prediction tool.
3. Assess the biological control potential of a newly discovered parasitoid wasp that may reduce risk of RSG damage to caneberries and play a role in an IPM program.
Approach:
Objective 1: A survey of 12 commercial PNW caneberry field sites will be used to ascertain RSG risk to crops and key risk determinants. Ambient temperature and relative humidity at each site will be recorded with data loggers. Four geographically-distinct 100-row-feet sections and adjacent stands of wild hosts per site will be used to collect data on 1) percent of row-feet with RSG damage after harvest in 2020, 2) after pruning in 2021, and 3) after harvest again in 2021. Data on relative adult RSG population counts will be collected on these areas through July 2021 using beating trays. Weekly scouting will facilitate data collection on RSG emergence dates, duration of adult activity, and phenological development through examining 4 RSG-damaged canes samples/site/week. Passive sticky traps will also be assessed for accuracy and applicability in an IPM program. Nine locations in northwest Washington will also be scouted intensively once in Fall/Winter 2020 to determine if RSG has spread north of King County, Washington, and a local agricultural professional will be trained and employed for RSG monitoring in 2021.
Objective 2: A laboratory study will be used in conjunction with data from the field survey in order to refine estimates of phenological development of RSG in the PNW environment. In the lab, RSG emergence will be artificially induced from a variety of PNW wild hosts and caneberries by manipulating the estimated thresholds for RSG phenological development that were observed in the 1960s. A minimum of 40 samples of RSG-damaged canes collected from each field site in Fall/Winter 2020 will be placed into four incubation chambers (~10 canes from each site/chamber) with differing temperature and relative humidity conditions. Samples will include representative canes that have been effectively girdled and those that are damaged, but un-girdled. The control treatment will be set at optimal temperature and humidity thresholds for unconstrained phenological development, while three other chambers will be set for sub-optimal 1) relative humidity, 2) temperature, and 3) humidity and temperature combined.
Emergence data will be collected twice per week. The percentage of canes lacking emergence will be recorded and examined for phenology stage and examined for other plausible causes of RSG mortality.
Objective 3: Sampling for the Baryscapus wasp (and other possible natural enemies) will occur in conjunction with data collection for RSG. Wasps collected will be sent to UC-Riverside for identification to species. Canes containing wasp larvae or adults will be recorded and compared to the number of canes lacking a viable RSG. Geographical distributions of wasps found, and dependent factors (RSG host species, variety, etc.) will be recorded for compiling summary statistics. The project team will conduct a literature review determine if the identified species is a known parasitoid of RSG or related Buprestids.
