By Carter Peru, AAg, BSc, Integrated Pest Management Agrologist
The 2019 pest survey season is currently underway and has started with a number of different insect surveys. Diamondback moth pheromone traps were set up at the beginning of May and will be monitored into June. The pheromone used in the delta traps attracts male diamondback moths. Diamondback moths do not overwinter in significant numbers in Saskatchewan. Adult moths are blown in on wind currents from the south. The pheromone traps provide an indication of when diamondback moths have arrived and also provide an estimation of population levels. The data collected from the diamondback moth survey is used to provide regular updates on our Diamond Back moth web page.
Pheromone traps are useful as an early warning system. However, in-field monitoring for the presence of the diamondback moth larvae is required to guide insecticide application decisions. The economic threshold for diamondback moth when canola is in the advanced pod stage is 20 to 30 larvae per 0.1 m2, or approximately two to three larvae per plant. More information on diamondback moth monitoring and economic thresholds can be found on the Prairie Crop Pest Monitoring Blog.
The aster leafhopper survey is also being done in conjunction with the diamondback moth survey. Yellow sticky cards used to catch aster leafhoppers are set up near the diamond back traps. Aster leafhoppers are a concern in canola, flax, wheat, and many other crops due to the phytoplasma disease aster yellows, which they may transmit when feeding on host plants. This survey is being led by Agriculture and Agri-Food Canada (AAFC) in Saskatoon and will be used to support ongoing research.
The bertha armyworm survey will begin the first week of June. Supplies to monitor more than 250 sites have been sent out to cooperators throughout the province. Similar to the diamondback moth survey, pheromone traps are used to attract the adult male moths. Bucket-style traps are used to capture the moths. Cooperators report moth counts every week during the monitoring season to the Ministry of Agriculture. This data is used to create a weekly cumulative bertha armyworm population map, which was most recently updated in August of 2018. The 2019 bertha maps will soon be available. If you are interested in participating in the bertha armyworm survey, please email firstname.lastname@example.org.
Higher moth numbers in mid-June to July generally indicate a greater risk of damage in July and August. The bertha armyworm survey provides a regional assessment of risk, giving farmers and agrologists an early warning of a bertha armyworm outbreak. Insecticide application decisions must be made based on the levels of larvae present in a specific field, which can be assessed through in-field monitoring. In-field monitoring for larvae should begin as soon as adult moths are noted to be present. More information on bertha armyworm monitoring and economic thresholds can be found on the Prairie Crop Pest Monitoring Blog.
The pea leaf weevil survey begins once field peas are at the second node stage. During this survey, surveyors assess field pea plant for the distinctive notching damage that adult pea leaf weevils cause on foliage. A detailed overview of the pea leaf weevil survey and pea leaf weevil management practices can be viewed in the “Pea leaf weevils in pea and faba bean fields" article included in this issue.
Many more insect surveys will be beginning shortly. Disease surveys will begin in July. Watch for updates in future Crop Production Issues to learn more about crop pest surveys.