VCR – Vegetable Crop Report – September 15th, 2022

This will be the final week for the 2022 edition of the Vegetable Crop Report.

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Temperature – All counties continue to match or surpass their 10 year GDD average except Peterborough. Peterborough’s cumulative GDD dropped earlier in July with some cooler temperatures but afterwards has followed the same upward trend as the 10 year average. Southern Ontario daytime temperatures are forecasted to remain in the mid- to high- 20s this week before dropping at the end of the week. Eastern Ontario may see temperatures in the low- to -mid 20s and northern Ontario may see some days in the high-teens.

Precipitation – All regions received at least some rain over the last week. Norfolk has now received just under half of it’s 10 year average rainfall for September. Essex and Kemptville have now received approximately one third. Southern and eastern Ontario can expect some rain at the start of the week with the risk of thunderstorms in some areas. Rain and possible thunderstorms are also in the forecast in northern Ontario over the weekend and into the start of the week.

Crop Updates

Brassica Crops – Harvest continues throughout Ontario. Alternaria is becoming more of an issue in fields with the extended periods of leaf wetness. An Emergency Use Registration (EUR) for SWITCH® 62.5WG Fungicide was approved from July 8th, 2022, until July 7th, 2023 for broccoli, cauliflower and Brussels sprouts as it is fully registered on cabbage and leafy brassicas. We are monitoring for Alternaria fungicide resistance, so if you would like a sample analyzed from your field, please contact travis.cranmer@ontario.ca. Be on the lookout for bacterial head rots, especially in cabbage that is going into long-term storage. Diamondback moths have been an issue in some regions for head brassicas this year and the level of thrips is starting to accumulate in some storage cabbage fields. The final wave of cabbage maggot has met its degree day threshold for Wellington, Peterborough and Sudbury. Dig up wilted plants with a shovel and inspect roots for maggots, nematodes or clubroots to properly identify the pest/pathogen. If you or field hands are interested in Brassica pest and pathogen training, we will be hosting a Brassica IPM workshop in spring 2023. A registration announcement will be posted on the ONvegetables blog in early 2023.

Celery – Harvest continues throughout Ontario. Monitor for leaf curl, sclerotinia and bacterial rots. When scouting late in the season, avoid moving through the crop in the morning when the leaves are wet as pathogens can spread easily on clothes/equipment throughout the field. Continue to monitor for aphids, tarnished plant bugs, aster leaf hoppers, and leafminers.

Garlic – Garlic planting has started across SW Ontario for the 2023 crop. If you are purchasing planting stock, it is extremely important to purchase cloves that are free of stem and bulb nematode. Even cloves with an intact basal plant and no observable damage my have nematodes present. The post: Things to consider before purchasing garlic planting stock gives a good summary of the things to look for when purchasing garlic planting stock. For growers using Chateau at planting, be sure to apply the product within the time frame that is indicated on the label. Crop injury is observed regularly in several fields where Chateau was applied greater than 3 days after planting.

Onions – Harvest is underway. No downy mildew outbreaks have been confirmed in Ontario. In green onions, keep an eye open for leaf miner damage, including distorted leaves and brown pupae (Figure 1) within the compromised leaf as seen in this post about Allium leaf miner. If Allium leaf miner damage is found, please contact travis.cranmer@ontario.ca. We will be hosting an onion and carrot pest and pathogen workshop in spring 2023. A registration announcement will be posted on the ONvegetables blog in early 2023.

**Figure 1.** Allium Leafminer pupa on onion. If pupae are found, please contact travis.cranmer@ontario.ca. Photo by L. Donovall, USDA APHIS.

Pest Degree Day Forecasting

*NOTE: Data as of September 14th, 2022

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
Essex*	2580	2406	1908	1605	1185	2070	2406	1460
Chatham-Kent*	2386	2217	1735	1441	983	1892	2217	1302
Norfolk**	2328	2162	1682	1383	921	1839	2162	1242
Huron***	2135	1973	1505	1216	773	1656	1973	1078
Wellington**	2070	1909	1443	1155	717	1595	1909	1023
Simcoe County***	2115	1953	1491	1203	766	1642	1953	1068
Durham***	2244	2078	1604	1311	857	1758	2078	1171
Peterborough	2015	1853	1388	1106	676	1539	1853	972
Kemptville***	2232	2063	1592	1304	849	1742	2063	1164
Sudbury***	1895	1749	1320	1049	628	1461	1749	921