Temperature – Daytime temperatures are forecasted to stay in the low thirties over the weekend and drop out into the twenties for many regions during the next week. All regions minus Peterborough remain above their GDD 10-year average.
Carrot Rust Fly is in its third and final threshold in Sudbury. Cabbage Maggot is at its final threshold in the regions of Norfolk, Huron, Simcoe, Durham, and Kemptville. European Corn Borer is at its threshold in the bivoltine region of Chatham-Kent and the overlap region of Norfolk. GDD data for each region is shown below.
Rainfall – Most regions are forecasted to have rainfall starting Saturday and going through the weekend ending on Monday. All regions except for Essex are behind their 10-year precipitation averages by at least 20mm. Precipitation data for each region is shown below.
Brassica Crops – Cabbage maggot is active in many areas across the province. Alternaria is becoming more widespread across the province over the past week. Bacterial rots and downy mildew are present in some areas while tip burn is becoming prevalent again in fields with low amounts of moisture. Pressure from imported cabbageworms, and diamondback moths remain high. Avoid scouting or working in the crop when the crop is wet and start from the cleanest plantings first and move to plantings with known pathogens later in the day. Continue to scout for cabbage aphids, Sclerotinia white mould and Fusarium yellows.
Carrots – Aster yellows incidence is high this year. Alternaria and Cercospora leaf blights are increasing as well, use a 25% incidence spray threshold for fungicides.
Celery – Conditions have been favourable for bacterial blight. Continue to scout for Cercospora, Septoria as well as celery leaf curl. Disc harvested blocks to reduce pest pressure and plant a cover crop to prevent soil erosion in areas that have been harvested.
Onions – The pressure of thrips is building due to favourable conditions and in some cases, they are migrating from lodging or harvested fields. The risk of downy mildew varies but areas with heavy dews in the morning and longer periods of leaf wetness are at higher risk. Royal MH can be applied for sprout control when 50% of the crop has lodged and there are green tops that are still present to absorb the product. Apply Royal MH at least 10 days before the crop is harvested.
Potatoes – With the hot weather recently late blight risk has lessened but later harvested fields still need to be protected from late blight. Aphids have been seen in some fields, scout for aphids on the underside of potato leaves.
Pest Degree Day Forecasting
*NOTE: Data as of Aug 25th, 2021
|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|
*- 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: