VCR – Vegetable Crop Report – June 18th, 2026

vegetablecropreport

12 hours ago

Crop Updates

Brassica Crops – Harvest has begun in early planted broccoli in the southern-most regions of the province. Slugs, flea beetles (Figure 1), and imported cabbageworms damage has been the most common so far with aphids (Figure 2), cutworms, and diamondback moths (Figure 3) causing damage as well. Rhizoctonia / wirestem is present in many fields and Alternaria is active in early plantings on the oldest leaves. Alternaria development will likely be within the next two weeks as the rain this week is creating conditions of high humidity and prolonged periods of leaf wetness. Early detection and management of Alternaria will reduce potential inoculum later in the season. Alternaria resistance has been documented in other regions outside of Ontario and it is important to rotate FRAC groups after every fungicide application. Dig up wilted plants and look for the root cause, whether it’s cabbage maggot, clubroot, nematodes or some other factor.

**Figure 1 –** Flea beetles feeding on a brassica plant – June 11, 2026.

**Figure 2 –** Aphids feeding on a Brussels sprouts plant – June 8^th, 2026. M. MacDonald.

**Figure 3 –** Diamondback moth larvae feeding on a cabbage plant – June 8^th, 2026. R. Colautti.

Celery – Plants are establishing well in fields with adequate moisture available up until this past week. Cutworms, tarnished plant bugs 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 – Plants are starting to bulk up with bulbs differentiating into cloves. Witches broom (Figure 4) is common throughout southwestern Ontario this year in heavier soils where there was extended periods of soil saturation. While there may not have been standing water in these fields in the past few months, there were extended periods where the top layer of soil was consistently wet for a significant duration of time. This excess moisture may have resulted in the plant growing extra cloves outside of the main bulb and as these cloves are forming, their leaves are extending up the stem and emerging at the same place where the scape emerged over the past week. Witches broom is primarily found in porcelain cultivars, such as Music. This disorder may result in some unmarketable bulbs depending on where these extra cloves form. Garlic rust has been identified and will become more prevalent over the next two weeks as the rain this week is creating conditions of high humidity and prolonged periods of leaf wetness. Garlic rust often starts first in areas of the field that are near windbreaks due to the lack of wind (and potentially sun) drying out the crop. Aprovia is registered for garlic rust on garlic – OCPH Garlic x Garlic Rust. In future years, avoid planting in the headlands or areas of the field that are shaded for any length of time. If the crop can be planted so that the rows are parallel to the predominate winds, this may also allow the field to dry out faster after morning dews or rainfall events. The second flight of leek moth is active, and larvae will be hatching from eggs soon (Figure 5). The second flight of leek moth has started in Chatham-Kent, Essex and Lambton and will likely be starting soon throughout the rest of 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. Pay special attention to fields that are senescing, or in garlic cultivars that are harvested earlier, as leek moth larvae will follow the green tissue down into the bulb if they are actively feeding near harvest.

**Figure 4 –** Additional leaves emerging next to the scape, known as ‘witches brooming’ – June 16^th, 2026.

**Figure 5 –** Leek moth larvae on garlic – June 11^th, 2026, D. Bianchi.

**Figure 6 –** A monarch choosing to make its chrysalis on a garlic plant – June 16^th, 2026.

Onions – Cutworms are still being found, but most larvae are large, close to pupating, and insecticides applications are unlikely to be cost effective at this stage. The pressure of thrips continues to be low in direct seeded onions, but are starting to build in transplants. Past research has shown that Movento 240 SC (group 23) has some residual activity that works better against larvae when it is applied twice earlier in the season. Once the spray threshold has been met, Movento 240 SC could be followed by two applications of Delegate (group 5) or Agri-Mek (group 6). Using a penetrating surfactant can be useful to maximize the effectiveness of products against thrips. Apply no more than two consecutive insecticides from the same IRAC crop as thrips have a relatively short life cycle with multiple generations through the summer months and are at a high risk of developing insecticide resistance. Stemphylium development will likely be found over the next two weeks as the rain this week is creating conditions of high humidity and prolonged periods of leaf wetness. Over the next couple of weeks, monitor for damage caused by the second generation of onion maggot larvae.

Peppers – The first peak of European corn borer is ongoing in overlap and one-generation areas, like Essex and Kent counties. However, the second peak will be more of a concern for growers, as the plants will have fruit at that time. Nighttime temperatures have been a bit low recently and peppers really struggle with cooler weather. Growers should be on the look of for chilling injury, which could set plant growth and flowering back a bit.

Potatoes -With these recent rains and thunderstorms, it’s important to get a fungicide on. Potatoes will be growing vigorously and weather is conducive for disease.

Rutabaga – The first generation of cabbage maggot should now be finishing up egg-laying and damage may be starting to show. Verimark applied in-furrow is registered against cabbage maggot. Reminder that Cimegra and Success also temporarily received Emergency Use Registration on rutabagas for the 2026 season. For more details see the OnVegetables post: Cimegra® and Success® Insecticide labels temporarily expanded via EUR – ONvegetables

Tomatoes – Tomatoes were doing well last week with the heat, but this week nighttime temperatures have been lower and there could be some chilling injury seen in some areas. With the recent storms, growers should also be on the look out for bacterial speck and spot beginning in the fields. There are only copper products available for treatment of these diseases and they is mainly effective on bacterial speck, not bacterial spot.

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***	553	484	298	200	101	355	484	160
Essex*	959	870	625	477	289	704	870	409
Chatham-Kent*	854	768	533	399	242	609	768	343
Norfolk**	768	688	478	358	206	542	688	302
Huron***	676	598	395	283	154	459	598	235
Wellington**	644	572	386	279	154	443	572	232
Simcoe County***	640	570	388	282	162	445	570	237
Durham***	688	614	420	309	181	481	614	262
Peterborough	651	579	391	285	156	451	579	238
Kemptville***	703	631	430	321	192	494	631	275
Sudbury***	495	439	300	223	126	343	439	188
Timiskaming***	473	419	292	220	129	329	419	188
Lambton**	751	668	450	334	186	518	668	281
Thunder Bay	370	318	195	136	63	230	318	109
Middlesex*	765	685	471	351	200	539	685	296
Renfrew	615	550	372	278	170	428	550	240