Temperature – Day temperatures are forecasted to range from mid-teens to low-twenties based on region.
Nighttime temperatures are forecasted to be in the high single digits to low teens for most regions. The Growing Degree Day values have continued to increase faster than the previous 10-year averages, especially in the past week. Degree Day data for each region is shown below.
Rainfall – The forecast mostly sunny or partly cloudy for a majority of regions until Wednesday, June 2nd. Wrapping up with May, there has been very little rain in most regions, with most being behind by over 30mm. Precipitation data for each region is shown below.
Brassicas – Head brassicas are establishing well. Imported cabbageworms, flea beetles and even diamondback moths are active. Observe the roots of wilted transplants and look for wireworms or cutworm larvae. Check stunted plants for wirestem. Seedcorn maggot has reached the threshold for first generation emergence and cabbage maggot will be emerging soon in most regions across the province and is likely already active in Essex and Chatham-Kent.
Celery – Transplants are establishing well, and most fields have been planted across Southwestern Ontario. The threshold for aster leafhopper has been reached in Essex, Chatham-Kent, Norfolk, Huron, Wellington, Simcoe, Durham, Peterborough, Kemptville, Sudbury and every county has had enough growing degree days for tarnished plant bug.
Garlic – The most advanced plants have 9 leaves, but the majority have 6 across the province. Plants in warmer areas, such as Essex are starting to scape which is early. Leek moth trap counts are low in areas where the moth has established.
Onions – Seeding and transplant onion planting is mostly complete across the province. Seeded onions are growing slowly in areas without adequate moisture and are anywhere from the flag to 1st leaf stage while most fields are past the first leaf stage. Transplants have established well in fields that have received adequate levels of moisture. Both onion and seedcorn maggot flies are active across most regions. If wilting is observed, dig up the roots and look for larvae of maggot flies, or wireworms to confirm the insect that caused the damage.
Carrots – Dry conditions continue in most areas of the province with the majority of the carrots now seeded. Irrigation is ongoing and might be needed to ensure consistent germination this season.
Potatoes – With the bulk of potato planting wrapped up, we could use a little bit of rain. Many fields have adequate moisture below but the top is quite dry. Don’t be surprised with reduced activity from pre-emergent herbicides this year unless you can irrigate them or we receive some rain to activate them. Keep an eye out for emergence issues.
Pest Degree Day Forecasting
*NOTE: Data as of May 26th, 2021
|Pest||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|
*- 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: