VCR – Vegetable Crop Report – May 23rd, 2024

Welcome back to the next VCR Report of 2024! Currently, all counties are above their ten year average for GDD.

Crop Updates

Brassica Crops –The degree day threshold for cabbage maggot emergence has been met in Essex, CK, Lambton and Middlesex counties which means eggs should be hatching out soon. Cimegra (active ingredient broflanilide, IRAC group 30) has been temporarily registered as an emergency use for cabbage maggot management for broccoli, Brussels sprouts, cabbage, and cauliflower for use from May 17, 2024 to December 31^st, 2024. Broflanilide is a new active ingredient that can be applied as a post-planting drench banded spray. For best results, apply at peak egg laying activity based on sticky card counts or growing degree days for your region. Otherwise, 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. Use the table below to determine if the degree day threshold for cabbage maggot has been reached or visit the ONvegetables Weather Dashboard, select your region to determine if the thresholds have been met since this VCR has been published. Slugs have been an issue along field edges in some areas and swede midge is likely active if they have been a problem in the field in past years.

Carrots – Aster yellows in carrots is spread by aster leafhoppers (Fig. 1). Early season testing in Michigan is finding very high infectivity and high counts of aster leafhoppers which is abnormal for this early in the season. If you have early planted carrots, get your orange sticky cards up or start sweep netting to monitor for populations.

Fig. 1. Aster leafhopper on sticky trap.

Garlic – Many plants are still green to the tip across the province. 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 being reached for onion maggot in many regions over 20 days ago, damage from larvae have been observed over the past two weeks. Set up damage plots by counting out 100 plants in four areas of the field to determine what percentage of onions are lost over the next few months due to damage by maggot fly larvae or other pests.

Potatoes – Planting in the SW counties of Ontario has pretty much wrapped up. Planting in Central Ontario continues in-between rain events with around 60% of the crop planted in the region. With the milder winter, expect a higher number of volunteers to have survived and overwintered. Manage them in rotational crops as well as possible to prevent an early source of late blight. Higher numbers of Colorado Potato Beetles will also likely have overwintered. Adult Colorado Potato Beetles have already been spotted walking around fields so be sure to scout populations and ensure your at-plant insecticide treatment is holding up. Hopefully if you’re seeing adults they look like this: (Fig. 2).

A reminder that Potato Scout Training will be on Wednesday June 5^th. You can register here: 2024 Integrated Pest Management Training Registration Form – V2 (site.com)

Our survey for soft rots and blackleg samples continues all season long. If you’re seeing blackleg symptoms on emerging plants or if you had any questionable seed you didn’t plant, we’d like your samples. More details here: Potato Bacterial Soft Rot Survey – ONvegetables

Tomatoes – planting has begun for processing tomatoes and fresh market tomatoes are starting with their staggered planting schedules. Be sure to keep an eye out for early season insect pests like black cutworm (Fig. 3), wireworm (Fig. 4) and Colorado potato beetle (Fig. 5) . These pests are becoming more of an issue with the loss of some key insecticides and early detection is key to managing them effectively. Make sure to read all product labels carefully before any pesticide application.

Fig. 3. Damage to tomato transplant caused by black cutworm.

Fig. 4. Wireworm damage and larva inside tomato transplant stem

Fig. 5. Colorado potato beetle egg mass on underside of tomato leaf.

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***	389	331	194	124	53	233	331	97
Essex*	618	548	366	270	148	422	548	227
Chatham-Kent*	550	484	317	231	118	367	484	189
Norfolk**	517	450	276	190	93	328	450	153
Huron***	456	394	235	155	76	283	394	122
Wellington Centre**	426	363	217	143	64	259	363	111
Wellington North**	416	356	211	141	65	254	356	110
Simcoe***	414	354	209	134	58	252	354	101
Durham***	451	387	231	152	68	277	387	119
Peterborough	414	353	207	131	57	250	353	102
Kemptville***	442	381	240	167	86	280	381	137
Sudbury***	297	252	148	97	46	179	252	76
Timiskaming***	283	244	150	100	48	177	244	79
Lambton**	525	462	296	208	110	347	462	171
Thunder Bay	200	159	70	36	8	93	159	24
Middlesex**	543	477	305	216	114	357	477	179
Renfrew	425	366	226	159	80	267	366	130