VCR – Vegetable Crop Report – June 2nd, 2022

Temperature – All counties continue to meet or rise slightly above their 10 year average GDD trends. Daytime temperatures have dropped to the mid- teens to low 20s after yesterday’s stormy weather and they are forecasted to remain consistent throughout next week. Some counties may see single digit nighttime temperatures at the start of the weekend.

Precipitation – All counties received at least some rain over the past week. However Norfolk county received approximately 40% of it’s 10 year average rainfall total for June yesterday with a whopping 36.4mm and Simcoe received approximately 25%. Most counties fell slightly behind their 10 year average rainfall for May except for Wellington, which was slightly above, and Kemptville which received almost double their 10 year average total monthly rainfall. Rain and possible thunderstorms in most counties are forecasted for after the weekend and again towards the end of the week. A few counties may also see rain with a risk of thunderstorms tonight continuing into tomorrow.

Crop Updates

Brassica Crops – Transplants are establishing well if there is adequate moisture with some plants showing wilting on days over 30C. The threshold for the first-generation emergence of cabbage maggot has been reached in most regions other than Sudbury. Flea beetles, swede midge, slugs and cutworms (Figure 1B) remain active. Diamondback moths and imported cabbageworms are likely to be observed very soon. Pull up wilted plants and inspect roots for insect larvae. Wilted plants may be due to heat, millipedes (Figure 1A) or seedcorn maggot damage and if the leaves are turning purple, the wilt may be due to wirestem, caused by Rhizoctonia (Figure 1C).

**Figure 1**. Scout for transplant damage from millipedes (A), cutworms (B) and wirestem/Rhizoctonia damage (C).

Celery – Transplants are establishing well, and most fields have been planted across Southwestern Ontario. The thresholds for aster leafhopper and tarnished plant bug has been reached across the province. Dig up wilted plants and inspect the roots/plug for cutworm larvae.

Cucurbits – Striped cucumber beetles (Figure 2) are migrating to pumpkin, squash, cucumber, and melon fields. If an insecticidal seed treatment, such as thiamthoxam, was not used, be prepared to make a foliar application. The threshold is one beetle per plant. The beetles cluster feed, so large numbers will commonly be found on random plants, or in specific areas of a field. Beetle feeding at this stage has a high risk of transmitting the bacterial wilt pathogen. Where an insecticidal seed treatment has been used, it is common to find large numbers of dead beetles at the base of the plant along with some feeding damage. Beetles ingest the insecticide while they feed. It is also common for the beetles to enter the field in flushes. Frequent scouting is important to properly determine if a foliar insecticide application is warranted.

Garlic – Plants are starting to send out the scape leaf and the scapes on ‘Music’ are starting to emerge. Scapes will likely emerge in most regions in SW Ontario over the next 5-10 days. Tipburn is widespread across the province this year and may be due to frost damage, lack of moisture over the past month or herbicide injury. It is difficult to find plants that are still green to the tip. Irrigation may be required for bulbs to size well in areas that have had little precipitation over the past month. Continue to scout for damaged leaves as this will likely be due to leek moth damage. Leek moth leaves what looks similar to sawdust on the top of the leaves (Figure 3). Depending on the area, the second flight of leek moth will be active over the next two to three weeks. Use sticky cards with lures to monitor populations, and target the second generation of larvae a week after the peak flight. Register for the next Garlic Production and Pest Management workshop near Janetville, ON, that takes place Friday, August 19^th from 9:30-4:30. Register by calling 1-877-424-1300 or filling out this online form: https://survey.clicktools.com/app/survey/go.jsp?iv=1y59n0qcz8rld.

Figure 3 – Look for feeding damage caused by leek moth on leaves that is similar look as sawdust. June 2nd, 2020.

Leafy Greens – Cutworms are active and leafy greens that are grown from seed are at a greater risk. If leaves look like they were cut at the soil line in the field, dig up around the plant to look for cutworm larvae (Figure 4). The larvae comes out at night to feed, so if management strategies targeting this pest are implemented, it should be when the larvae are active and the product can make contact.

Figure 4 – Dig around seedlings where leaves have been cut at the soil line; there’s a good chance damage is caused by night feeding of cutworm larvae.

Onions – Earliest direct seeded onions are at the third leaf stage while the majority of fields are in the flag or 2nd leaf stage. Transplant are doing well given they have had enough moisture to establish. Onion maggot flies are active in all regions; be on the lookout for wilted plants. Control volunteer onions in neighbouring fields as this can be a source for fungi inoculum like Stemphylium or pests like onion thrips. Also be on the lookout for black cutworms over the next two weeks. Cutworms can cause damage that looks like the onion has been cut with scissors above the soil line (Figure 4). Dig around suspect plants to look for cutworm larvae within the top inch of the soil surface.

Pest Degree Day Forecasting

*NOTE: Data as of June 1, 2022

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
Essex*	613	545	361	268	163	418	545	229
Chatham-Kent*	535	472	308	226	129	359	472	194
Norfolk**	549	488	324	234	130	376	488	198
Huron***	490	433	280	200	109	326	433	168
Wellington**	465	409	258	181	97	305	409	153
Simcoe County***	462	405	258	179	98	303	405	150
Durham***	503	441	282	200	102	331	441	164
Peterborough	452	405	246	171	81	292	396	139
Kemptville***	507	443	286	208	110	332	443	174
Sudbury***	354	315	207	149	80	241	315	126