VCR – Vegetable Crop Report – July 24, 2025

Welcome back to the next VCR of 2025!

Currently most counties are trending slightly above their 10 year average GDD, with Sudbury, Thunder Bay, and Timiskaming county trending slightly below their 10 year average.

Crop Updates

Cucurbits – Spider mites can be damaging to a wide range of horticultural and field crops, including cucurbits and snap beans. Hot spots of activity have been identified in East Elgin and Norfolk. They thrive in hot, dry conditions and often appear in fields grown on sandy-loam soils. Product selection can be challenging due to resistance, longer pre-harvest intervals and varying levels of knock-down activity.

Look for plants with off-coloured leaves, a bronze coloured stippling, or areas of yellow leaf tissue between darker green veins. Mite damage can easily be confused with other types of injury, including nutrient deficiencies and air pollution.

bean plants heavily infested with spider mites

Thrips have also been found in cucumbers. Their feeding damage is slightly different. Their rasping mouthparts remove the tender tissue on the lower leaf surface, leaving and bleached or silver appearance on the upper leaf surface. Like mites, it also tends to appear in the areas between the leaf veins.

Both insects will cause crop stress, aborted fruit and lower overall yields.

Potatoes – Late blight remains the main concern at this time. A second field of late blight on potatoes has been reported in Dufferin County, near the first occurrence. As mentioned in the latest Late Blight Update, with thunderstorms over the next few days, chances of spore spread are high. Ensure you have adequate protection with late blight specific fungicides. Now is a good time to apply P-acid products for foliar and tuber protection. P-acid products have shown to be an important part of successful late blight programs over the last 2 years.

Late blight sporulation viewed under a microscope. These sporangia can be blown long distances, especially in thunderstorms.

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 legend below
Bruce***	1168	1059	759	588	372	853	1059	512
Chatham-Kent*	1481	1358	1014	817	561	1121	1358	726
Durham***	1341	1229	921	732	494	1020	1229	647
Essex*	1587	1462	1112	903	627	1224	1462	807
Huron***	1297	1181	870	691	464	967	1181	612
Kemptville***	1355	1245	933	747	514	1033	1245	665
Lambton**	1429	1306	972	779	534	1078	1306	693
Middlesex**	1453	1334	999	800	548	1106	1334	711
Norfolk**	1400	1280	945	751	510	1051	1280	663
Peterborough	1259	1148	840	662	436	938	1148	582
Renfrew	1344	1236	929	749	521	1028	1236	667
Simcoe***	1281	1169	866	686	465	962	1169	608
Sudbury***	1025	933	675	527	333	757	933	460
Thunder Bay	896	808	566	422	237	642	808	355
Timiskaming***	993	902	655	512	320	733	902	444
Wellington Centre**	1268	1156	846	665	440	945	1156	585
Wellington North**	1271	1160	848	676	450	947	1160	598