VCR – Vegetable Crop Report – May 16th, 2024

Crop Updates

Brassica – Transplanting continues across the province. The first-generation threshold for cabbage maggot has been reached in the warmest parts of the province and adult flies will be laying eggs. Currently 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. Scout for flea beetles and early imported cabbage worm damage.

Garlic – The number of leek moth catches has gone down in most areas over the past week. Many fields have reached 10 leaves per plant and will be sending out a scape soon. The Garlic Growers Association of Ontario is hosting the 2024 field day Saturday, June 1st at Van Raay Farms near Dashwood, Ontario. Equipment from multiple manufacturers will be on display, along with products from fertilizer and pest control product suppliers. The agenda includes a tour of a new garlic curing and storage facility along with a field tour of cultivar, clean seed, intercropping and planting date trials. Registration starts at 10:00, the agenda starts at 10:30 and goes until 3:30. Lunch will be provided. Van Raay Farms is located at 37871 Dashwood Road, Dashwood, Ontario, and all are welcome to join, rain or shine. Please register for the field day by going to https://www.garlicgrowersofontario.com/event-details/field-day-2024-2.

Onion – With the threshold for the first generation of onion maggot reached in many locations over the past two weeks, eggs are hatching out and larvae damage is starting to be observed in transplant fields (Figures 1 & 2). 2023 was the last year to use Lorsban / chlorpyrifos products for maggot management. Transplants are at the greatest risk since no products are registered as a transplant drench, and seed treated with Sepresto 75 WS will have likely worn off by the time the onion is transplanted. Releasing sterile onion maggot flies has shown to successfully manage onion maggot in 2500 acres of onions in Quebec and nearly 100 acres of onions in Ontario. More information about this technology can be found in this past ONvegetables article: How sterile flies replaced Lorsban for two onion growers

Figure 1 – Transplant starting to wilt due to onion maggot larvae, May 14, 2024.

Figure 2 – Recently hatched, first-generation onion maggot larvae found in the transplants shown in Figure 1, May 14, 2024

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***	295	243	127	71	22	160	243	51
Essex*	497	434	273	191	90	322	434	155
Chatham-Kent*	436	377	231	159	67	274	377	125
Norfolk**	410	350	198	126	50	243	350	96
Huron***	351	296	158	92	34	199	296	66
Wellington Centre**	319	263	138	78	20	173	263	54
Wellington North**	310	258	133	77	23	170	258	53
Simcoe***	310	257	133	72	17	169	257	46
Durham***	345	288	153	88	25	193	288	62
Peterborough	312	258	133	71	19	170	258	49
Kemptville***	326	271	151	93	32	184	271	69
Sudbury***	195	157	75	37	8	98	157	23
Timiskaming***	180	148	74	39	7	95	148	24
Lambton**	407	351	205	132	55	249	351	101
Thunder Bay	138	105	36	16	4	53	105	11
Middlesex**	414	356	208	135	57	252	356	106
Renfrew	316	264	145	92	34	179	264	71