VCR – Vegetable Crop Report – May 8th, 2026

Welcome to the first vegetable crop report of the season!

Crop Updates

Brassica Crops – Transplanting of Brassicas has been ongoing for the past couple of weeks in warmer areas of the province. Some early fields that were planted may show frost damage with the outer most leaves turning purple or yellow. While it has not been warm enough for cabbage maggot fly to reach its first-generation growing degree threshold in any county, seedcorn maggot is likely active in southern counties like Essex and Chatham-Kent.

For preventative measures against cabbage maggot in broccoli, Brussels sprouts, cabbage, and cauliflower, tray drenches of Success (Group 5), Entrust (Group 5), and Verimark (Group 28) are registered. For in-furrow transplant applications, Verimark (Group 28) and Cimegra (Group 30) are registered. Cimegra was recently approved for use against cabbage maggot in Canada in April, but the U.S.A. has yet to approve the use pattern. Therefore, with the lack of export MRLs, Cimegra can only be used on head Brassicas destined to be sold in Canada. Keep on the lookout for cutworm damage over the next couple of weeks (Figure 1).

**Figure 1** – Cutworm damage on a Brussels sprouts transplant – June 3^rd, 2020.

Carrots – Early seeded carrot fields have now been sitting in cool and wet soil conditions so keep an eye out for Pythium damping off (Figure 2).

**Figure 2** – Carrot taproot with brown discoloured areas from Pythium infection.

Garlic – Plants are anywhere between the 4^th and 8^th leaf stage depending on where and when they were planted (Figure 3). Yellow tips are prevalent in areas that have experienced excess moisture (Figure 4). Now is the time to set up leek moth traps. Allium leafminer was confirmed in Niagara in the fall of 2025. Allium leafminer’s first generation generally occurs in mid-April to the end of May in the Northeastern United States. In garlic, oviposition scars (Figure 5), may be seen on garlic leaves. Keep an eye out for maggot feeding damage to the leaves. As far as winterkill / early spring stunting, the biggest issues are:

Planting too late so that the cloves do not have adequate time to establish roots before winter

Cloves panted after mid-November result in roots that do not have enough root establishment to prevent frost heaving
Consider planting earlier in the season (September to Early October)

Cracking and waiting to plant will allow for secondary pathogens to colonize the wounds from the cracking process and weaken the cloves

Cloves should be planted within 7 days of cracking

Stem and bulb nematode in low amounts can weaken the clove and lead to fewer plants successfully overwintering

Fall application of Velum Prime at planting may increase survival rate

Seedcorn maggot fly larvae, millipede and wireworm damage the roots of garlic plants as they are emerging in March / April

Plants wilt and dry up quickly giving the illusion that the missing plants were winterkilled when in fact the plants survived the winter and were damaged by maggot larvae early in the season
Dig up wilted plants and look for maggots, millipedes or wireworm

Herbicide carry over from previous crops

Some herbicides will cause stunting if garlic is planted even after many months have passed
Refer to the herbicide re-cropping table for garlic to be sure adequate time has passed since a particular herbicide has been applied

Saturated soils that experience significant freeze-thaw cycles over several weeks will weaken plants and may cause winterkill

Consider planting in raised row/beds in heavier soils

**Figure 3** – Garlic around the 6^th leaf stage in Huron County – May 1^st, 2026.

**Figure 4** – Garlic showing yellow tips in areas with excess moisture – May 8^th, 2026.

**Figure 5** – Extremely small, white, oviposition (egg laying) scars from Allium leafminer on a garlic leaf in New Jersey – April 7^th, 2026 (Photos M. Cramer, Rutgers.)

Onions – Onion transplanting and seeding is underway in warmer areas of the province. The first generation of onion and seedcorn maggot has met its threshold in Essex and Chatham-Kent. Take the time to destroy volunteer onions in last year’s fields to help limit the potential inoculum source for this year’s crop (Figure 6). Register now for the Onion IPM Scouting workshop on Wednesday, May 12th. Onion insect and pathogen scouting will be the focus of the in-person and virtual workshop. Register Online or call the Agriculture Information Contact Centre at 1-877-424-1300.

**Figure 6** – Downy mildew identified on some overwintering onions in a community garden in Guelph – May 6^th, 2026.

Potatoes – It’s certainly not an early start to the season for most of the province. After starting on schedule in SW Ontario with growing degree days tracking above the 10-year average things have averaged out in the last week. The Central and Eastern regions of the province have started cool and wet. In these conditions make sure cut seed has suberized prior to planting to prevent seed issues and rot. To ensure healing and suberization:

forced-air circulation through the shallow pile
temperatures of 10°C–15°C (50°F–59°F)
high relative humidity of 90%–95% (prevent free water from forming on tuber surfaces)

Maintain these conditions for 3–4 days. After this, the temperature may be lowered, but humidity must be maintained and fans run intermittently.

Select a region below for the latest weather, crop and pest degree day information: