VCR – Vegetable Crop Report – July 7th, 2022

Temperature – All regions continue to match or surpass their 10 year average GDD except for Peterborough which is falling marginally behind. Daytime temperatures are expected to run high this week in the mid- to high twenties and may feel like the 30s throughout most of Ontario. Huron county may be slightly cooler but will still see temperatures in the 20s and possibly feel like 30 some days with the humidex.

Precipitation – All regions have started off July receiving some rain over the past week. Sudbury has received almost a quarter of its 10 year precipitation average already. In most regions there is a chance of rain over the weekend with a risk of thunderstorms in some regions and again into the beginning of the week or midweek. Huron county however has only a small chance of rain in the middle of the week.

Crop Updates

Brassica – Cauliflower harvest is underway. Rapid growth due to heat and excess moisture may lead to nutrient deficiencies, tip burn and hollow stem in broccoli over the next couple of weeks. Alternaria is active and early detection and management of Alternaria will reduce potential inoculum later in the season. Incorporate all left over plant tissue immediately after harvest to lower the amount of inoculum available to infect later plantings. Continue to scout for lepidopteran pests, aphids and thrips.

Celery – Plants are establishing well. Aster leafhoppers continue to be active, and the numbers caught in sticky cards are relatively high for this early in the season. Scout and rogue plants showing yellow leaves, symptoms of aster yellows. Scout for tarnished plant bugs and scratch marks along the stalk left by carrot weevils. Rogue out yellow plants in the field that show aster yellows symptoms. Leaf blights (Figure 1) such as Cercospora (early blight), Septoria (late blight) and celery leaf curl are more likely to be seen if there was rainfall over the past week.

Figure 1. Celery leaf with both Cercospora (early blight) and Septoria (late blight) lesions. Cercospora lesions are tan to yellow spots while Septoria lesions are the grey to black spots.

Garlic – Harvest is quickly approaching and some fields are quickly senescing if they are overly stressed. Depending on how quickly your soil dries out, avoid irrigating too close to harvest as soil stuck to the bulb will make it more difficult to achieve a clean wrapper. If black plastic has been used for weed control, cutting it open to allow the soil to dry before harvest can also help with wrapper cleaning. If leek moth counts were high last week, consider targeting the larvae that are now feeding on the crop. While you may not have seen a lot of damage while scaping this year, by targeting these larvae on the crop now you are reducing the amount of overwintering moths and the potential damage to future seasons.

Onion – Stemphylium has been observed in multiple fields across the province (Figure 2). If Penflufen was part of the seed treatment, do not start a Stemphylium fungicide program with a foliar group 7 fungicide. For the first application, a product containing mancozeb (group M3) may provide protection. Mancozeb products such as Manzate Pro-Stick, Dithane Rainshield, and Penncozeb 75 DF Raincoat are registered for Botrytis and Manzate Pro-Stick is registered for Botrytis and Alternaria/Purple Blotch. Avoid applying products from the same chemical group one after the other. The level of thrips is starting to climb. 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 as the first insecticide.

Figure 2. Stemphylium lesions developing on a direct seeded onion – June 2021

Peppers – Peppers are progressing well with the heat and are starting to set fruit. Some much needed moisture would be a huge help to the plants right now. There seems to be more Japanese beetles flying around this year and they are migrating into pepper crops in search of food. These beetles can cause quite a bit of feeding damage on foliage, so keep an eye out for them in your crop. You can identify a Japanese beetle by their iridescent brown-green colour, a line of white dots along either side of their body and the three forked end of their antennae (Figure 3). Pheromone baited traps are available and can help bring numbers down when used properly.

Figure 3. Adult Japanese beetle on pepper plant

Tomatoes – Tomato crops are progressing nicely and early plantings already have 4 or more sets. There was some pollution damage seen, especially in Kent county, just over a week ago, but the plants are pulling through. This time of year it is important to continue with your general fungicide program to keep anthracnose and early blight at bay. It is also good to keep an eye out for signs of late blight in your crop. There have been years where late blight was seen as early as the beginning of July.

Another pest to scout for at this time of year is stink bug. Stink bugs are thought to migrate into tomatoes as wheat is harvested. Look for adults (Figure 4) and nymphs (Figure 5) that like to hide deep in the plant canopy. Another way to scout for stink bugs is to look for the damage they cause like dimples (Figure 6) and light-coloured, snowflake patterns (Figure 7) on the fruit. Once stink bugs are found in your crop, you should follow a weekly spray program to keep numbers as low as possible. This is a very difficult pest to scout for and control. If you think you have a stink bug problem, please reach out to amanda.tracey@ontario.ca for information and guidance.

Figure 4. Adult stink bugs on tomato leaves

Figure 5. Stink bug nymph on tomato fruit

Figure 6. Stink bug dimple damage on Tomato Fruit

Figure 7. Light-coloured, snowflake patterned stink bug damage on tomato fruit

Pest Degree Day Forecasting

*NOTE: Data as of July 6, 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*	1277	1174	886	722	512	977	1174	648
Chatham-Kent*	1120	1022	753	601	385	839	1022	534
Norfolk**	1119	1023	753	594	370	840	1023	523
Huron***	959	866	608	459	254	689	866	391
Wellington**	953	862	607	459	258	688	862	396
Simcoe County***	962	870	618	469	271	699	870	405
Durham***	1022	926	662	509	293	746	926	439
Peterborough	926	834	580	437	233	660	834	371
Kemptville***	1035	936	674	526	310	755	936	457
Sudbury***	807	732	520	391	208	589	732	333