VCR – Vegetable Crop Report – August 1st, 2024

Welcome back to the next VCR of 2024!

Almost all counties continue to trend above their 10 year average GDD, with the exception of Thunder Bay which is on trend with its 10 year average.

Crop Updates

Brassica Crops – Nutrient disorders have been a common problem in head brassicas, from tip dieback on leaves to uneven head development to leaf edema. Conditions have been favourable for Xanthomonas or black rot of Brassicas. Populations of thrips are increasing and could become problematic in cabbage.

Cucurbits – Phytophthora infections are being reported in watermelon, pumpkin and squash across the SW Ontario growing region (Fig. 1). Once established in a field, there are no effective treatments that will control the spread. If the infection is limited to an isolated area, and has not begun to spread, destroying the infected plant may prevent further spread.

**Fig. 1** Phytophthora capsica on watermelon

Garlic – Harvest has mostly finished. As garlic cures, check bulbs in the middle of pallet boxes or totes regularly to get a good sense of how the entire crop is drying out. Thinking of planting a new cultivar or purchasing new planting stock for 2024? Test any new planting stock for bulb and stem nematode before planting in your field. Low levels of nematodes can be found in planting stock that otherwise looks great. Here is an article summarizing the things to consider before purchasing new garlic planting stock: https://onvegetables.com/2022/08/05/garlicplanting/

Onions – Transplants continue to be harvested. Some areas may still be at a high risk for onion downy mildew given the high humidity and heavy dews. Stemphylium continues to progress in many fields, especially those where the older leaves are senescing early due to excess moisture. Bacterial blights are common in fields that were flooded in the past.

Sweet corn – Aphid populations are still uncommonly high and appearing in many late-planted fields. Heavy aphid pressure at the pre-tassel stages is a concern. If colonies form on the tassels prior to pollen-shed, they may prevent pollination and kernel formation on the cob.

Also of note, vegetable research day is coming up this August the 15th at Ridgetown Campus at the University of Guelph. A flyer with details about the event can be found below.

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***	1412	1284	937	727	452	1046	1284	631
Chatham-Kent*	1749	1614	1236	1010	688	1356	1614	899
Durham***	1606	1472	1106	887	593	1223	1472	784
Essex*	1885	1744	1353	1116	784	1478	1744	1003
Huron***	1532	1399	1030	811	529	1148	1399	709
Kemptville***	1612	1480	1130	917	626	1239	1480	816
Lambton**	1719	1586	1209	982	675	1330	1586	874
Middlesex**	1733	1597	1215	986	675	1337	1597	879
Norfolk**	1684	1547	1163	937	630	1285	1547	830
Peterborough	1512	1381	1025	809	526	1139	1381	710
Renfrew	1609	1480	1130	923	636	1241	1480	824
Simcoe***	1509	1380	1025	810	528	1138	1380	707
Sudbury***	1314	1200	886	695	440	986	1200	604
Thunder Bay	1104	993	694	522	299	787	993	443
Timiskaming***	1291	1181	877	691	444	975	1181	603
Wellington Centre**	1519	1386	1030	816	528	1142	1386	715
Wellington North**	1499	1369	1014	804	524	1128	1369	704