VCR – Vegetable Crop Report – August 11th, 2022

Temperature – Most regions continue to match or surpass their 10 year GDD cumulative averages except for Peterborough, which is still fairly below, and Sudbury which is lagging slightly behind this week. Temperatures are trending lower this week with daytime highs in the low- to mid- 20s throughout the province and nighttime lows in the teens.

Precipitation – Essex has now received more than half it’s 10 year average cumulative rainfall for August. Chatham-Kent and Wellington have also now received almost half their averages. Rain is forecasted for mid week in many parts of the province though little to no rain is expected for Essex, Chatham-Kent and Sudbury in the upcoming week.

Crop Updates

Brassica Crops – Lepidopteran pests, thrips and aphids continue to be active. The level of Alternaria has been low this year but is starting to show in some fields. Bacterial soft rot has been observed in some fields and tip burn has been seen in others.

Celery –Septoria leaf spot as well celery leaf curl has been observed with bacterial rot in some fields. Avoid walking through the fields when the humidity is high, and the leaves are wet as celery leaf curl spores will stick to clothes and equipment. Fields with larger fluctuations in moisture are showing blackheart and tip dieback in some plants. Tarnished plant bugs, Leafminers and aster leaf hoppers are active.

Garlic – Most garlic has been cured and is going into storage. Once cured, table stock can be kept at a temperature 0.5°C at a relative humidity of 50-70% and planting stock can be kept at 10°C (up to 18°C) at a relative humidity of 55-65%. If purchasing new planting stock for the 2022-2023 season, refer to the article published no August 5^th – Things to consider before purchasing garlic planting stock. To learn more about garlic production, we are offering a full day workshop near Lindsay (Janetville) on August 19th that will cover every part of garlic production including cultivar selection, seeding density, weed control, scaping, crop insurance, harvesting, grading, storing as well as pest and pathogen management. To register, call the agriculture contact centre at 1 877-424-1300. GGAO members should E-mail garlicgrowersofontario@gmail.com to place an order for clean seed roundels for planting this fall.

Onions – Transplants are being harvested and some direct seeded fields are starting to lodge. The threat of downy mildew remains high, especially if inoculum is present from previous years. If the DOWNCAST forecasting model is not available to predict outbreaks for your area, a protective fungicide program for downy mildew is recommended during the humid weather we have been experiencing. Past research at the Muck Station has shown that Orondis Ultra (groups 40/49), Zampro (groups 45/40) and Ridomil Gold MZ (groups 4/M3) are the most effective for controlling this disease and are most effective when they are applied as a protective application before infection can occur. Stemphylium leaf blight is slowly causing tip dieback, but is not as severe relative to previous years for mid-August. As fields of transplants are harvested, be mindful of younger, direct-seeded onions in border fields as the level of thrips may surge as they move to a greener crop

Peppers – Early maturing varieties are beginning their first pick. Plants look really good with some minor cases of bacterial spot being reported so far. Last week brought the first report of anthracnose on peppers (Figure 1) in Kent County. With the discovery of a more aggressive species of anthracnose in this area in 2021, it is important that growers maintain their preventative, general fungicide programs and scout for anthracnose lesions on all fruit. Table 1 has a list of fungicides currently registered in peppers with activity against anthracnose.

Figure 1 – First anthracnose lesion reported on banana pepper fruit in Kent County – August 3, 2022

Table 1. Fungicides registered on field peppers for the 2022 field season for anthracnose.
** Note that captan is an Emergency Use Label for one year.

Active ingredient	Product	FRAC Group	Maximum # of applications per year	Pre-Harvest Interval (days)
copper sulphate	Copper 53W	M1	10	2
captan **	Catan 80 WSP	M4	3	2
pyraclostrobin	Cabrio	11	6	0
azoxystrobin/ difenoconazole	Quadris Top	11 & 3	3*	1
difenoconazole/ benzovindiflupyr	Aprovia Top	3 & 7	4*	1
difenoconazole/ pydiflumetofen	Miravis Duo	3 & 7	2*	0
fludioxinil/cyprodinil	Switch	12 & 9	3	0

For more information please see the blog post from March 14, 2022: Anthracnose Control in peppers – the old and the new.

Tomatoes – Tomatoes are looking very good in most growing regions of the province. Early varieties will be gearing up for harvest towards the end of August. On July 29, 2022 late blight (Figure 2 and 3) was observed in tomatoes in Ottawa county Ontario. Typically, late blight spores are blown in on strong winds from the south, but that was not the case in this isolated incidence. Thus, the risk of late blight for growers outside of the immediate region of this case is still very low. Late blight has not been reported outside of the state of Florida and the environmental conditions in much of Ontario have not been conducive for disease development until very recently. Growers should remain aware of the risk in the area by staying up to date on blog posts, like the Late Blight Update posted on August 4, 2022. Growers should continue with their general fungicide program and consider late blight specific fungicides only if there are symptoms in the field or in a field very nearby.

With the recent rains sweeping across the province there has also been an increase in the amount of fruit rot caused by Phytophthora capsica, especially in Essex and Kent counties, where crop rotations have been on the shorter side. Growers should be on the look out for buckeye rot on green fruit and red fruit turning into “water balloons”, especially in lower areas of the fields. There are some control options that can help to protect the remaining fruit. The storms also brought in more bacterial spot. Although there is not much growers can do to minimize the damage from bacterial spot on fruit and foliage, they should still keep an eye out for symptoms and minimize contact with wet plants in these areas.

Figure 2 – Dark-green to brown, greasy foliar lesion caused by *Phytophthora infestans*, the causal agent of late blight.

Figure 3 – Brown fruit discolouration and bumpy skin texture cause by *Phytophthora infestans*, the causal agent of late blight.

Pest Degree Day Forecasting

*NOTE: Data as of August 10th, 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*	1971	1833	1440	1206	892	1567	1833	1097
Chatham-Kent*	1777	1644	1270	1048	713	1391	1644	945
Norfolk**	1754	1623	1249	1019	677	1371	1623	913
Huron***	1566	1438	1076	856	533	1191	1438	754
Wellington**	1536	1410	1049	832	512	1166	1410	734
Simcoe County***	1564	1437	1080	861	544	1195	1437	762
Durham***	1660	1529	1160	937	602	1279	1529	832
Peterborough	1483	1356	997	784	473	1112	1356	685
Kemptville***	1669	1535	1168	950	614	1284	1535	846
Sudbury***	1365	1255	938	739	437	1042	1255	646