VCR – Vegetable Crop Report – May 11th, 2023

Welcome to the second week of the VCR Report for the summer! Fields have started to dry out and planting is underway across the province.

Brassica crops – Cabbage maggot is likely active in Essex county and nearing its first-generation threshold in several other counties. Seedcorn maggot fly is likely active in Essex, Chatham-Kent and Lambton counties. Dig up wilted transplants and inspect roots for insect damage. 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. Be on the lookout for flea beetle emergence as the soil temperature reaches above 10°C. If you were unable to attend the 2022 Brassica Crops IPM Scout Training workshop, a recorded version can be viewed below: https://www.youtube.com/watch?v=fHf0y1xG0kI

Garlic – Plants are at an average of 4-8 leaves. Cool weather as well as herbicide applications, have caused leaf yellowing in many fields. The nightly lows have not been above the 9.5°C required for leek moth in most regions, however, leek moth has been detected and is likely active across the province in sheltered areas that experienced warmer night temperatures. Seedcorn maggot fly damage has been observed in SW Ontario and has reached its first-generation threshold in Essex, Chatham-Kent and Lambton counties. Dig up plants that have wilted leaves to look for seedcorn maggot larvae, wireworms or millipedes as described in last week’s VCR.

Onion – Transplanting is underway across the province and many fields have been direct seeded in drier areas. The threshold for seedcorn and onion maggot fly have been reached in Essex, Chatham-Kent and Lambton counties. If you were unable to attend the Onion IPM scouting workshop, a recorded version can be found at: https://www.youtube.com/watch?v=OwGISdtuNEU

Carrots – We have not reached the Degree Day threshold for any carrot insect pests to emerge. With a warm weekend we should reach emergence of carrot weevil in the SW regions of the province.

Potatoes – Be mindful of applying herbicides in cool, wet soil conditions as efficacy is generally decreased and potential for crop injury is increased.

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***	153	126	67	40	18	84	126	31
Essex*	274	227	123	80	35	150	227	63
Chatham-Kent*	249	206	113	73	35	139	206	59
Norfolk**	228	186	101	64	30	124	186	49
Huron***	182	147	81	52	25	98	147	41
Wellington**	177	148	85	56	29	104	148	46
Simcoe County***	194	162	92	64	36	112	162	53
Durham***	201	165	86	54	23	106	165	43
Peterborough	194	162	86	55	28	106	162	45
Kemptville***	216	184	106	66	28	129	184	50
Sudbury***	122	101	52	26	6	67	101	16
Timiskaming***	109	88	33	11	0	49	88	6
Lambton**	243	204	112	76	39	138	204	61
Thunder Bay	43	29	4	0	0	11	29	0
Middlesex*	222	184	103	67	31	125	184	53
Renfrew	178	147	72	37	9	94	147	25