VCR – Vegetable Crop Report – June 11th, 2026

Crop Updates

Brassica Crops – Slug damage is common around field edges. Damage from imported cabbageworms, cutworms, flea beetles and diamondback moths continues to be observed in many regions. To determine if the threshold for management has been met for imported cabbageworm, diamondback moth or cabbage looper (Figure 1), scout 5 plants in 5 locations and record the total number of each lepidopteran pest found (total number of egg or larvae found):

Multiply:

Diamondback moth x 0.2 = A

Imported cabbageworm x 0.5 = B

Cabbage looper x 1.0 = C

Then add and divide:

A+B+C divided by 25 = Cabbage Looper Equivalent

For cabbage, the threshold is 0.3 and for broccoli and cauliflower the threshold is 0.2.

**Figure 1 –** Eggs (inset) of diamondback moth (left), imported cabbageworm (middle), and cabbage looper (right). Larvae of diamondback moth (left) are pale green, leave window-pane damage on the leaf from feeding, wiggle frantically when disturbed and attach a silken thread and sometimes dangle over the leaf edge. Imported cabbageworm larvae (middle) are velvety in appearance and have a pale-yellow stripe along their back. Imported cabbageworm larvae photo: Dr. Mary Ruth McDonald. Cabbage looper larvae (right) are smooth with a thin white line along each side and two faint lines down the middle of the back.

Carrots – Carrot weevils are currently active and laying eggs (Figure 2). Refer to the Crop Protection Hub for registered products for carrot weevil. The recommendation for most products are applications around the 2-leaf, 4-leaf or 6-leaf stage depending on carrot weevil pressure in your field.

**Figure 2** – Adult carrot weevils in a Boivin trap.

Celery – Transplants are establishing well. The thresholds for aster leafhopper and tarnished plant bug have been reached across the province with the exception of Thunder Bay. Dig up wilted plants and inspect the roots/plug for cutworm larvae. Scout for carrot weevils as they may be emerging around the field borders.

Cucurbits – Reports from the Southern US are suggesting that it has been very little downy mildew activity so far this year. In Michigan, Dr. Mary Hausbeck’s spore trapping program has detected cucurbit downy mildew (clade 2) spores at four locations in recent weeks. Downy mildew clade 2 infects cucumbers and cantaloupe. Scout fields regularly and report any potential infections to OMAFA. If left untreated, downy mildew is highly infectious and can spread rapidly. Good communication = effective control.

As crops continue to emerge, keep an eye out for striped cucumber beetle. The beetles can transmit bacterial wilt while feeding. Once a plant becomes infected, there is no control for bacterial wilt. Use a spray threshold of 0.5-1 beetle per plant.

Garlic – Plants are starting to bulk up with bulbs differentiating into cloves and scapes are starting to emerge. Snap scapes of hardneck cultivars as soon as possible to obtain the greatest yield benefit. Avoid using sickle bar mowers to remove scapes as they can easily spread garlic pathogens (including viruses) and often clip leaves during the scape removal process. While scaping, be on the lookout for leek moth as well as symptoms of stem and bulb nematode, botrytis neck rot, fusarium basal rot and white rot (Figure 3). If leek moth counts were high last week, consider targeting the larvae that are now feeding on the crop. The second generation of leek moth larvae were active in Lambton, Chatham-Kent, Middlesex, Niagara and Norfolk this week.

**Figure 3** – Symptoms of stem and bulb nematode, Fusarium Basal Rot, Botrytis neck rot, and white rot.

Onions – Onions are starting to take off with the increase in heat over the past week. Onion maggots continue to be active with the first generation of growing degree days reached now in all regions across the province. Did up wilted plants and inspect roots for onion maggot larvae. Check transplants and established onions for thrips over the next week. 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. For a full list of insecticides registered for thrips, refer to the Crop Protection Hub.

Peppers – Processing pepper planting is wrapping up shortly. Plants needed the rain badly and should start perking up now. Cutworms are around and doing some feeding. Growers should scout fields and spot spray as needed to minimize damage to transplants.

Potatoes – Emerging potatoes will have the highest concentration of seed treatment insecticides and should do a good job of controlling feeding Colorado Potato Beetles (Figure 2). Colorado Potato Beetles are active and laying eggs so check on the underside of leaves for clusters of yellow egg masses (Figure 3).

**Figure 2** – Adult Colorado Potato Beetle next to an emerging potato plant.

**Figure 3** – Yellow Colorado Potato Beetle egg mass on the underside of a potato leaf.

Snap beans – Bean leaf beetle (Figure 4) activity has been reported in Kent County. The threshold is 20% leaf defoliation prior to bloom and 10% after bloom.

Sweet corn – We have had reports of both cutworm and armyworm activity. When assessing cutworm, consider the size of the worm. Once they have reached 1.5” in length they have completed their life stage. They will stop feeding and pupate. There was an increase of armyworm moth catches in late-May to early-June. Eggs laid at that time will be aggressively feeding now. We often see an upswing in feeding activity in horticultural crops as the cereal crops begin to dry down. Look for feeding damage on the leaves and signs of frass in the whorls.

Tomatoes – Tomato planting is finished for processing growers. Plants are growing nicely, and the recent rain will help them thrive. There is some Colorado potato beetle and cutworm pressure noted in the area and growers should make sure to scout fields and spot spray if necessary. Targeting the larval stages of Colorado potato beetles is best, so if growers are seeing mostly eggs, waiting a few days before spraying would be the best option.

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***	457	395	230	146	68	280	395	113
Essex*	835	754	529	395	228	601	754	334
Chatham-Kent*	738	659	445	324	188	514	659	275
Norfolk**	658	585	396	290	160	453	585	242
Huron***	569	499	316	218	110	373	499	177
Wellington**	545	481	315	222	118	365	481	182
Simcoe County***	536	472	311	220	121	361	472	182
Durham***	582	515	342	244	138	396	515	205
Peterborough	553	487	321	229	120	373	487	189
Kemptville***	589	524	344	249	141	400	524	209
Sudbury***	402	353	234	171	96	271	353	143
Timiskaming***	376	329	223	165	95	253	329	140
Lambton**	633	558	360	259	131	421	558	213
Thunder Bay	290	245	144	98	45	172	245	78
Middlesex*	674	600	404	296	164	466	600	247
Renfrew	527	466	304	220	127	355	466	187