VCR – Vegetable Crop Report – May 8th, 2025

Welcome back to the next VCR Report of 2025! Excluding the northern counties of Sudbury, Thunder Bay, and Timiskaming, all counties are currently trending above their 10 year average GDD.

Crop Updates

Brassica crops – Transplanting continues. Seedcorn maggot is active in Essex, Chatham Kent, Lambton, Norfolk and Middlesex counties and nearing its first-generation threshold in several other counties while cabbage maggot fly is still a while away given the cooler weather we have been experiencing. 2023 is the last year to use Lorsban / chlorpyrifos products for maggot management. Success (Group 5) and Verimark (Group 28) are registered as greenhouse tray drenches and Verimark can also be used as an in-furrow application in the transplant water at the time of transplanting. An Emergency Use Registration for Cimegra has been approved for broccoli, Brussels sprouts, cabbage, and cauliflower against cabbage maggot for the 2025 field season. Be on the lookout for flea beetle emergence as soil temperatures go above 10°C and cutworm damage. In the greenhouse, play close attention to any yellowing leaves in plug trays and catch bacterial and fungal pathogens before they spread throughout the greenhouse.

Garlic – Plants are at an average of 5-8 leaves. Most plants are past the 5th leaf stage, so avoid applying nitrogen to reduce the number of rough bulbs at harvest as well as to encourage longer storage life. Cooler weather as well as herbicide applications, have caused leaf tips to yellow in many fields. The first leek moth flight has concluded across Southwestern Ontario and eggs are likely to be hatching out and larval feeding may be observed in the next two weeks. Seedcorn maggot fly damage has been observed in SW Ontario and has reached its first-generation threshold in Essex, Chatham Kent, Lambton, Norfolk, and Middlesex counties and nearing its first-generation threshold in several other counties. Dig up plants that have wilted leaves to look for seedcorn maggot larvae, wireworms or millipedes.

Onion – Transplanting is underway across the province and many fields have been direct seeded warmer regions across the province. The threshold for seedcorn and onion maggot fly have been reached in Essex, Chatham Kent, Lambton, Norfolk, and Middlesex counties and nearing its first-generation threshold in several other counties. The cool, dry weather has made it difficult for some seeded fields to germinate evenly and transplants have been slow to establish. Once seeded onions have emerged, count out 25 plants per row and put a marker at each end and record the number of plants every week. These damage plots will be valuable to monitor the amount of damage due to maggot flies or other pests.

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***	162	130	59	32	6	78	130	21
Chatham-Kent*	302	255	139	90	36	171	255	71
Durham***	189	155	80	43	11	102	155	30
Essex*	336	287	165	106	43	201	287	83
Huron***	236	196	107	66	24	132	196	50
Kemptville***	207	172	89	51	17	113	172	38
Lambton**	286	239	131	83	31	163	239	64
Middlesex**	263	222	119	73	23	148	222	55
Norfolk**	277	233	125	76	25	156	233	56
Peterborough	194	158	76	45	15	99	158	34
Renfrew	185	153	75	41	16	97	153	30
Simcoe***	190	154	74	38	7	97	154	26
Sudbury***	72	57	24	12	3	32	57	9
Thunder Bay	43	29	5	1	0	8	29	0
Timiskaming***	64	48	19	9	2	25	48	5
Wellington Centre**	205	168	85	48	11	110	168	32
Wellington North**	208	173	87	52	15	112	173	38