Weather Update
Many regions have recently fallen below their 10-year average in growing degree days as things start to cool off and become wetter.
Recent storms pushed August rainfall above the 10-year average in most regions, with some receiving more than double the average. September has also started wet, with many regions already receiving 20 to 30 mm (0.8 to 1.2 inches) of rain and locally higher amounts.
For more specific data see below for a list of regions and counties
Crop Updates
Brassica Crops – Conditions continue to be very favourable for many fungal and bacterial pathogens including Alternaria, black rot, downy mildew and sclerotinia. Numbers of aphids, diamondback moths and tarnished plant bugs continue to be high in multiple regions. Slug damage around field borders is also prevalent in some fields (Figures 1-2).
Garlic – Planting season has started. Cloves should be planted within 7 days of cracking to ensure vigour and best chance of overwintering survival. If Fusarium basal rot was an issue this past season, consider following:
- Follow a long crop rotation; aim for 7 or more years before returning to the same field
- Use planting stock with intact basal plates and looks disease-free
- Avoid planting garlic in fields that were wheat or sorghum Sudan grass was grown the previous season as there is some evidence that Fusarium species that colonize garlic are also a host in these crops (Fusarium proliferatum in wheat and Fusarium oxysporum in Sorghum Sudan grass)
- Consider planting in raised beds if the field is likely to be saturated with water at any point during the growing season
- Plant cloves after cracking as soon as possible and avoid planting anything that was split over 7 days ago
If you are still considering purchasing new planting stock for the 2026-2027 field season, remember that low levels of stem and bulb nematodes can be found in planting stock. Testing one bulb for every 200 lbs of planting stock or one in every 1000 bulbs could be a good indication of if there are nematodes present. Along with avoiding stem and bulb nematode, here are some other things to consider before purchasing new planting stock: https://onvegetables.com/2022/08/05/garlicplanting/.
Onions – Harvest has been postponed in many areas due to the rain events over the past week.
Potatoes – With the recent storms, weather has been ideal for a number of diseases but especially Late blight. Multiple regions (New York, Eastern Ontario (home garden), Quebec (earlier in the season), and Michigan) have now reported the presence of late blight at some point this season so risk is considered high for later harvested potatoes. Registered products can be found at this link. Wet harvest conditions also raise the risk of Pink rot, Soft rots and Pythium leak.
If you grew Colomba this season, did you see symptoms like those in the pictures below? In order to determine the extent, investigate some possible causes and find solutions, I’m interested in hearing from you. (contact: Dennis Van Dyk – 519-766-5337)
Snap Beans – be on the look out for two spotted spider mites. They often appear in the field edges along side dusty laneways or gravel roads. The symptoms are very subtle, until they aren’t! Look for yellowing between the leaf veins accompanied by bronze-to-brown stippling. Dirt will often stick to the lower leaf surface where the mites have left webbing. The mites themselves are very difficult to see with the naked eye and may require a 10x hand lens to confirm they are there. The following article outlines the current status of miticide resistance in Ontario as well as the identification of new species of mites feeding in beans.
Spider Mites Active in Some Fields – Scouting is Advised – Field Crop News
Sweet Corn – the recent storm activity puts sweet corn at higher risk of infestation by corn earworm, especially as trap counts in the mid-west have recently spiked. If you are trapping for corn earworm on your farm, consider reporting the findings to the Great Lakes and Maritimes Pest Monitoring Network. All corn at the green silk stage is attractive to egg-laying females.
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 below |
| Bruce*** | 1777 | 1630 | 1214 | 962 | 632 | 1348 | 1630 | 845 |
| Essex* | 2427 | 2263 | 1790 | 1490 | 1073 | 1944 | 2263 | 1345 |
| Chatham-Kent* | 2254 | 2091 | 1625 | 1336 | 948 | 1778 | 2091 | 1203 |
| Norfolk** | 2053 | 1897 | 1462 | 1192 | 816 | 1601 | 1897 | 1062 |
| Huron*** | 1945 | 1791 | 1356 | 1091 | 731 | 1497 | 1791 | 966 |
| Wellington** | 1882 | 1734 | 1318 | 1058 | 703 | 1451 | 1734 | 934 |
| Simcoe County*** | 1926 | 1778 | 1366 | 1106 | 755 | 1500 | 1778 | 984 |
| Durham*** | 2039 | 1888 | 1463 | 1197 | 839 | 1601 | 1888 | 1074 |
| Peterborough | 1918 | 1769 | 1350 | 1090 | 729 | 1487 | 1769 | 966 |
| Kemptville*** | 2029 | 1881 | 1452 | 1191 | 834 | 1591 | 1881 | 1068 |
| Sudbury*** | 1682 | 1551 | 1187 | 960 | 638 | 1305 | 1551 | 850 |
| Timiskaming*** | 1641 | 1510 | 1152 | 926 | 604 | 1266 | 1510 | 817 |
| Lambton** | 2154 | 1994 | 1545 | 1275 | 895 | 1690 | 1994 | 1145 |
| Thunder Bay | 1534 | 1405 | 1052 | 838 | 534 | 1164 | 1405 | 734 |
| Middlesex* | 2159 | 2002 | 1557 | 1283 | 901 | 1702 | 2002 | 1151 |
| Renfrew | 1754 | 1625 | 1256 | 1034 | 734 | 1376 | 1625 | 932 |
*- 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:
Bruce
Chatham-Kent
Durham
Essex
Huron
Kemptville
Lambton
Middlesex
Norfolk
Peterborough
Renfrew
Simcoe
Sudbury
Thunder Bay
Timiskaming
Wellington Centre
Wellington North
