By Tyce Masich, AAg, Crops Extension Specialist, Outlook
June 2024
Prior to the growing season, producers had major concerns regarding potential grasshopper damage to their crops. This was due to high populations in 2023 and mild winter conditions that favoured egg development. Hot and dry growing season conditions were initially forecasted for the 2024 growing season which further added to producer concerns.
Contrary to early season forecasts, much of the province has experienced cool and wet conditions this spring. These conditions likely did not kill or drown grasshopper eggs and provincial entomologist, Dr. James Tansey, doesn’t expect this to impact populations this summer. However, the cool and wet conditions seen in much of the province delays grasshopper emergence and allows crops to be more vigorous when grasshoppers emerge. This means there is a greater time buffer between grasshopper emergence and insecticide use, where yield loss from grasshoppers is minimal.
Grasshopper activity currently varies across the province. In some areas there have been reports of grasshopper nymphs feeding on crop seedlings. Some producers in southwest Saskatchewan near Fox Valley have sprayed insecticides multiple times this year due to the high populations. Maple Creek and Swift Current have nymphs in ditches and susceptible crops. Nymph damage in headlands and some insecticide application is also occurring in central Saskatchewan around Rosetown, Outlook, Aberdeen, Watrous, Humboldt and Strasbourg areas. Experts are predicting a hot summer in 2024 which means high grasshopper activity is expected in south, west and central Saskatchewan. Therefore, producers in these areas should frequently scout susceptible cereal, oilseed and pulse crops for grasshoppers this growing season.
Producers can predict grasshopper risks to their crops by reviewing the 2023 grasshopper survey map and considering grasshopper populations in their area last year. Insecticide application should be based on accurate grasshopper species identification and economic thresholds for specific crops. Only four out of the 85 grasshopper species in Saskatchewan threaten crops; therefore, species in your area should be identified as a pest prior to spraying. If a pest grasshopper species is in your fields, then monitor populations and consider spraying once populations exceed the economic threshold. For most crops, the threshold for grasshopper nymphs is 30-45 nymphs/m2. Economic thresholds for adult grasshoppers differ for each crop and are outlined below:
- Cereals: 8 to 12/m2
- Canola: 14/m2
- Lentils: 2/m2
- Flax (after bolls have formed): 2/m2
- Oats and field peas are not preferred by grasshoppers, but damage can still occur.
Various insecticide options that control grasshoppers can be found in the 2024 Guide to Crop Protection. Group 3 insecticides are effective at controlling nymphs. Producers need to be aware of restrictions on Lambda-cyhalothrin products such as Matador, Zivata, Labamba and Silencer. Lambda-cyhalothrin products cannot be applied to any crops used for animal feed or grazed by livestock.
For more information on grasshopper thresholds, damage and control measures, please call the Agriculture Knowledge Centre at 1-866-457-2377 where you can talk to your local crops extension specialist.