VCR – Vegetable Crop Report – September 17th, 2020

The weather and pest forecasting dashboard is live! Check out values specific to your region at https://onvegetables.com/weather-dashboard/

Temperature – Day temperatures remain in the mid-teens to low 20s across Ontario and

many regions will see single digit night temperatures into the weekend. Environment Canada has issued a frost warning in northern and eastern Ontario. Cabbage maggot is at threshold in Wellington and Peterborough. Degree day data for each region is shown below.

Rainfall – There is no rain in the forecast for southern Ontario over the next week but eastern and northern Ontario have a small chance of showers towards the end of next week. Sudbury has now met it’s 10 year precipitation average and Huron county has surpassed it’s 10 year average. Precipitation data for each region is shown below.

Crop Updates

Brassica Crops – Bacterial head rots in cabbage and broccoli are present in both southwestern and eastern Ontario. Downy mildew and Alternaria are widespread. Scout for aphids in the growing points of the plant and continue to monitor for late season flushes of thrips, especially in cabbage destined for storage.

Celery – Harvest continues. Multiple pathogens are present causing celery leaf curl, Cercospora leaf spot, Sclerotinia rot and bacterial rots. When scouting late in the season, avoid moving through the crop 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.

Cucurbits – Phytophthora fruit rot of pumpkin caused by Phytophthora capsici has been found in several counties. Symptoms often appear where the fruit is in contact with soil. Because conditions have been conducive to the development of this disease, now is a good time to monitor for low levels of disease. Phytopthora can build in soils and if low populations are present, crops should be rotated away from cucurbits and solanaceous crops. Phytophthora produces motile zoospores which are attracted to plant root exudates and can swim through water films and spread throughout wet fields. Improving drainage can be helpful in managing this pathogen. It is important to clean equipment and sanitize footwear between infested fields. Harvest of infested fields should be scheduled after healthy fields have been harvested where possible.

Cucumber beetles are still active and can cause direct feeding damage to the rind of cucurbits, reducing marketability and potentially leading to infection.

Figure 1. Cucurbit challenges. Clockwise from top left: Spotted cucumber beetle damaging watermelon rind, Simcoe ON, 8 Sept. Striped cucumber beetle on pumpkin, Elgin county, Sept 15. Leaky lesion on acorn squash, and similar symptom on buttercup squash showing underlying tissue damage Haldimand-Norfolk, Sept 15. Mild petiole infection by powdery mildew, Elgin county, Sept 15. Mini-pumpkin infected with *Phytophthora capsici,* 15 Sept.

Figure 2. A variety of decorative gourds ripening in the field. Elgin County, Sept 15.

Onions – Harvest is underway. No downy mildew outbreaks have been confirmed in Ontario.

NOTE: Data as of September 16th, 2020

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
Essex*	2543	2364	1873	1584	1179	2030	2364	1447
Chatham-Kent*	2352	2179	1714	1434	986	1861	2179	1299
Norfolk**	2330	2158	1680	1401	958	1831	2158	1266
Huron***	2067	1911	1478	1206	781	1617	1911	1074
Wellington**	2053	1891	1454	1187	774	1593	1891	1060
Simcoe County***	2092	1933	1500	1232	820	1640	1933	1104
Durham***	2244	2080	1629	1359	929	1771	2080	1228
Peterborough	2031	1867	1424	1155	740	1564	1867	1026
Kemptville***	2171	2010	1563	1296	880	1703	2010	1169
Sudbury***	1830	1688	1288	1043	665	1416	1688	926