VCR – Vegetable Crop Report – June 19th, 2025

Welcome back to the next VCR of 2025!

Currently most counties are trending close to their 10 year average GDD, with some trending slightly below and Bruce county trending slightly above.

Crop Updates

Brassica Crops – Harvest is about to begin in early planted broccoli and cabbage in the southern-most regions of the province. Be on the lookout for black rot, caused by the pathogen Xanthamonas campestris pv campestris (Figure 1). Black rot spreads rapidly during warm, humid weather and enters other plants through wounds or natural openings on the leaf tips. The Xanthamonas bacteria often finds it’s way to farms in infected seeds and then bacterial cells overwinter on used trays, propagation equipment and crop debris for up to three years. Infected plants have characteristic ‘v’ shaped lesions and systemically infected plants have chlorotic areas anywhere on the leaf. When leaves are held up to the sun, veins filled with Xanthamonas bacteria are stained black in the chlorotic areas on the leaf. The best management strategy is prevention through certified clean seed, sanitation of propagation equipment/tools, a four-year crop rotation, and rogueing and then burying all crop debris. Damage from cutworms continues to be a major issue in many fields. Slugs, flea beetles, and imported cabbageworms damage has been common. Fields that are extremely dry and have not been irrigated have shown symptoms of heat canker and edema.

Figure 1 – Black rot leaf on cauliflower with characteristic ‘V’ shaped lesion on leaf tip.

Celery – Plants are establishing well in fields with adequate moisture available. Cutworms, tarnished plant bugs, aster leaf hoppers and slug damage have been observed. Scout for yellow/orange scratch marks along the stalk left by carrot weevils or downward cupped leaves that could be due to celery leaf curl. Rogue out yellow plants in the field that show aster yellows symptoms. Dig up stunted and/or wilted plants and gently knock of soil to inspect their roots for nematode cysts, or carrot weevil larvae.

Garlic – Ensure plants have adequate moisture and consider irrigating over the next two weeks while plants are bulbing in order to achieve optimal yields. Avoid irrigating two weeks prior to harvest to make it easier to clean bulb wrappers after harvesting. Dig up plants that show advanced leaf dieback from the base of the plant upward and inspect basal plate for damage caused Botrytis neck rot or stem and bulb nematode. The second flight of leek moth is likely starting soon throughout Southwestern Ontario. If applying insecticides, a single insecticide application is most effective when it is applied 7-10 days after the date that corresponds to the peak moth capture. All insecticides registered for leek moth are most effective when they make contact with the leek moth larvae.

Onions – New cutworm damage is still being observed, but most larvae are large, close to pupating, and insecticides applications are unlikely to be cost effective at this stage (Figure 2). The pressure of thrips has continued to be low in direct seeded onions, but higher levels are being observed in transplants. Be mindful that onion fields next to hay or overwintering rye are at a greater risk to thrips once they are cut and include counts from at least one location near the field border when scouting for thrips. Past research has shown that Movento 240 SC (group 23) has some residual activity that works better against larvae when it is applied earlier in the season. Over the next couple of weeks, monitor for damage caused by the second generation of onion maggot larvae.

Figure 2 – Cutworm climbing an onion leaf. June 17, 2025.

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***	600	525	327	225	110	387	525	183
Chatham-Kent*	816	726	485	356	201	558	726	298
Durham***	697	620	413	292	157	478	620	241
Essex*	882	791	542	401	227	620	791	339
Huron***	691	609	400	289	164	463	609	244
Kemptville***	720	644	434	316	184	500	644	268
Lambton**	764	676	443	319	177	516	676	266
Middlesex**	799	713	481	350	201	553	713	294
Norfolk**	749	664	431	305	168	503	664	252
Peterborough	659	582	373	260	134	437	582	213
Renfrew	692	618	414	301	175	478	618	254
Simcoe***	655	577	376	265	145	438	577	220
Sudbury***	504	445	286	205	110	335	445	171
Thunder Bay	407	353	213	137	54	255	353	105
Timiskaming***	473	416	271	196	106	314	416	162
Wellington Centre**	664	586	378	265	142	443	586	219
Wellington North**	668	591	381	277	153	446	591	233