Welcome back to the VCR Report for 2023!
Brassica Crops – Plants are establishing well, and transplanting continues across the province. Diamondback moth has already been identified in Chatham-Kent, and imported cabbageworms are active in most counties. The nighttime lows have generally been above temperatures that would result in frost damage in head brassicas in most regions. In areas with hard frosts, plants may see older, outer-most leaves turn yellow and wilt over the next week. Plants that were not properly hardened off before transplant are at a greater risk of frost damage. It has not been warm enough for the first generation of cabbage maggot to reach its threshold in any county, however, adult flies are likely around in low numbers in more-protected areas. Dig up wilted plants and inspect the roots for wireworm or millipede damage.
Garlic – Cool nights have led to many fields showing yellow tips on older leaves, despite whether herbicides have been applied in the past. Leek moths have been captured in most areas across the province. Leek moths can be monitored to inform insecticide timing by using Delta 1 traps and more information can be found here: May 17, 2023 ONVeg article. Dig up wilted plants and look for Delia maggot larvae (Figure 1).
Onion – Most fields have been dried enough for the majority of transplants and direct seeded onions to be transplanted. Cooler nights have made it difficult for transplants to get established. Onion maggot flies have reached their threshold for the first-generation emergence in most counties and damage from early season activity will likely be observed shortly. Dig up wilted plants and inspect roots for onion maggot larvae. Once seeded onions have emerged, count out 25 plants per row and put a marker at each end and record the number of plants every week. These damage plots will be valuable to monitor the amount of damage due to maggot flies or other pests throughout the season.
Pest Degree Day Forecasting
|County||Carrot Rust Fly||Onion Maggot||Carrot Weevil||Aster Leafhopper||Tarnished Plant Bug||Cabbage Maggot||Seedcorn Maggot||European Corn Borer|
|THRESHOLD||329-395, 1399-1711||210-700, 1025-1515||138-156, 455+||128+||40+||314-398, 847-960, 1446-1604||200-350, 600-750, 1000-1150||See legend below|
*NOTE: Data as of May 18th, 2023
*- Bivoltine region for ECB. First Peak Catch: 300-350 DD, Second Peak Catch 1050-1100 DD
**- Overlap region for ECB. First Peak Catch: 300-350 DD Second Peak Catch 650-700 DD, Third Peak Catch 1050-1100 DD
***-Univoltine region for ECB. Peak Catch 650-700 DD
Use these thresholds as a guide, always confirm insect activity with actual field scouting and trap counts.
Select a region below for the latest weather, crop and pest degree day information: