Temperature – The cool wet spring has continued into the summer in all growing regions of Ontario with all counties marginally, to significantly behind their 10-year average degree day accumulations. While some regions are now receiving near average temperatures, late planting dates has slowed the growth and development of many crops in most planted areas compared to normal.
Rainfall – Rainfall has generally slowed in most regions again this week and planting in most regions is now near completion, or completed already. Kemptville and Norfolk county have exceeded their 10-year precipitation averages, while Chatham and Sudbury are quickly approaching their respective averages for June. The remaining growing regions range from significantly below, to marginally below their 10-year average rainfall totals for June.
Brassica Crops – Crop conditions have been favourable for Alternaria in some areas. Depending on the Brassica, not all fungicides are labelled for use; see Table 1 below for fungicides registered on different crop groups. Diamondback moths, imported cabbageworms, tarnished plant bugs and aphids are active. Cabbage maggot and flea beetle levels are high in several areas.
Carrot – Carrot weevil activity should be winding down in the Southern part of the province.
Celery – Carrot weevils are active. On celery, carrot weevils leave scratch marks along the stalk that turn a yellow/orange colour as the wounds heal. The degree day threshold for aster leafhoppers and tarnished plant bugs has been reached in all growing regions.
Garlic – Many areas have finished scaping and many fields are showing leaf tips starting to senesce. Tip dieback is likely due to stress which could be from infrequent soil moisture, lack of or surplus of nutrients or root dieback. Continue to scout for leek moth by looking for damaged leaves and stems. The frass and chewed pieces of leaf looks can look like sawdust on the leaves. Leek moths have been found in low numbers this past week but we are likely close to the second peak flight.
Onions – Direct seeded onions are at the 3rd to 6th leaf stage and transplants are up to 8 leaves in some areas. Stemphylium leaf blight has been detected in transplants and direct seeded onions and given the weather, keep scouting for Botrytis and downy mildew. Cutworm damage has been high in some fields and the level of thrips has been low thus far into the season. The second peak of onion maggot will be starting in many areas over the next couple of weeks.
Potatoes – We’ve seen potato leafhopper numbers jump in some fields. Be on the lookout for leafhoppers and symptoms of hopperburn (seen in the picture below). Overwintering Colorado Potato Beetle adults are active and laying eggs. Eggs are hatching and small larvae are being found in some fields. If you used a neonic at seeding, make sure you are using a different mode of action for any follow-up applications. If you are not seeing the control you usually do, please contact Dennis (519-766-5337) for free resistance testing.
Pest Degree Day Forecasting
|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: