VCR: Vegetable Crop Report – August 2, 2018

Temperature – All regions have accumulated more degree days than the 10-year average. A hot first half of July kept the current degree day accumulation on trend with the average and increased the gap in some areas.

Rainfall –  Rainfall has been the talk as of late. After a dry first half to July, many regions received some minor relief in the second half of the month. Some major downpours put some regions at or above their 10-year average. Some regions remain dry and below average including some parts of Essex, Bruce/Huron and Eastern Ontario. Spotty rainfall appears the be the norm.

Crop Updates

Brassica Crops –Tarnished plant bugs, flea beetles and Swede midge populations are high in many areas. Wilt symptoms are being seen in fields with high cabbage maggot pressure and clubroot. A clubroot survey to determine the clubroot pathotype / strain is underway; please contact travis.cranmer@ontario for more information if you find clubroot in your field. Continue to scout for diamondback moth, cabbage loopers, cabbageworm, aphids and thrips.

Carrots – Leafhopper counts have been fairly high so far. Aster yellows is starting to show up in some fields but in low amounts at this point. Leaf blight has also started to show up. Many fields have canopies closing so if growers want to get a white mold fungicide on with decent coverage near the base of the plant, now might be a good time.

Celery –Tarnished plant bugs and Aster leafhoppers are active and have been found in low to moderate levels. Blackheart and celery leaf curl has been identified in multiple areas.

Garlic – The hot weather in early July caused many growers in SW Ontario to harvest early. Many growers in the Southern portion of the province have finished harvesting while those growing in Central and Eastern Ontario are starting. This year leek moth was detected for the first time in Lambton, Chatham-Kent and Huron counties. Many fields had pre-mature tip yellowing and dieback this year which may be due to Stemphylium leaf blight – similar to what is seen in onions. While grading after harvesting, sell bulbs with a damaged basal plate for table stock and only keep bulbs with healthy, white roots for seed stock. We are offering a second Garlic Workshop on September 5^th from 9:30-3:30 that will cover all aspects of production and pest management of growing garlic in Ontario. Space is limited so please register early to avoid disappointment. Register by calling OMAFRA’s Agricultural Information Contact Centre at 1-877-424-1300.

Onion – A sporulation and infection period for downy mildew was reached in several onion growing regions over the last two weeks but there has been very few positive samples. Downy mildew of onions prefers cool temperatures below 22°C and wet conditions resulting in high relative humidity. Earliest direct seeded onions have reached the ten leaf stage while the majority of fields are in the eighth leaf stage. Onion maggot flies have reached their second generation in most regions and population levels are elevated. Many fields have had four insecticide applications to manage onion thrips as populations have been high in the hot weather during the first two weeks of July. Stemphylium leaf blight has been detected in most areas. Continue to scout for onion smut, purple blotch, botrytis, pink root and white rot.

Potatoes – Black cutworm tuber damage has been identified in Simcoe County last week. Look for small shotgun holes in the leaves and stems cut off near the ground. If you dig around the soil near damaged plants you can often find the larvae curled up as they only feed at night. Check out the OMAFRA factsheet on black cutworm at this link: CropIPM – Black Cutworm.
No late blight spores have been caught on the spore traps yet. Some Colorado potato beetle activity has been seen in some fields as the at-plant insecticides are wearing off. Some growers might need to spot or perimeter spray. If you applied a neonic at-planting never follow up with another Group 4 neonic. Rotate with an insecticide in a different group such as a Group 3, 5, 6, 15 or 28 insecticide.

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

Essex County
Chatham-Kent County
Norfolk County
Huron County
Wellington County
Simcoe County
Durham County
Peterborough
Kemptville
Sudbury

 

 

Essex County

Location	Onion Maggot	Seedcorn Maggot	Cabbage Maggot	Leek Moth	Carrot Weevil	Carrot Rust Fly	Aster Leafhopper	European Corn Borer
Essex	1556	1556	1341	1239	1239	1670	1042	947
For reference on the various thresholds, see table at the very bottom of this post.

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Chatham-Kent County

Location	Onion Maggot	Seedcorn Maggot	Cabbage Maggot	Leek Moth	Carrot Weevil	Carrot Rust Fly	Aster Leafhopper	European Corn Borer
Chatham-Kent	1590	1590	1269	1151	1171	1590	977	883
For reference on the various thresholds, see table at the very bottom of this post.

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Norfolk County

Location	Onion Maggot	Seedcorn Maggot	Cabbage Maggot	Leek Moth	Carrot Weevil	Carrot Rust Fly	Aster Leafhopper	European Corn Borer
Norfolk	1453	1453	1246	1122	1145	1561	950	856
For reference on the various thresholds, see table at the very bottom of this post.

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Huron County

Location	Onion Maggot	Seedcorn Maggot	Cabbage Maggot	Leek Moth	Carrot Weevil	Carrot Rust Fly	Aster Leafhopper	European Corn Borer
Huron	1306	1306	1105	995	1009	1410	819	729
For reference on the various thresholds, see table at the very bottom of this post.

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Wellington County

Location	Onion Maggot	Seedcorn Maggot	Cabbage Maggot	Leek Moth	Carrot Weevil	Carrot Rust Fly	Aster Leafhopper	European Corn Borer
Wellington	1305	1305	1103	991	1005	1410	816	723
For reference on the various thresholds, see table at the very bottom of this post.

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Simcoe County

Location	Onion Maggot	Seedcorn Maggot	Cabbage Maggot	Leek Moth	Carrot Weevil	Carrot Rust Fly	Aster Leafhopper	European Corn Borer
Simcoe	1309	1309	1109	456	1012	1410	825	734
For reference on the various thresholds, see table at the very bottom of this post.

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Durham County

Location	Onion Maggot	Seedcorn Maggot	Cabbage Maggot	Leek Moth	Carrot Weevil	Carrot Rust Fly	Aster Leafhopper	European Corn Borer
Durham	1399	1399	1195	542	1097	1504	907	816
For reference on the various thresholds, see table at the very bottom of this post.

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Peterborough

Location	Onion Maggot	Seedcorn Maggot	Cabbage Maggot	Leek Moth	Carrot Weevil	Carrot Rust Fly	Aster Leafhopper	European Corn Borer
Peterborough	1306	1306	1102	444	1003	1409	814	724
For reference on the various thresholds, see table at the very bottom of this post.

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Kemptville

Location	Onion Maggot	Seedcorn Maggot	Cabbage Maggot	Leek Moth	Carrot Weevil	Carrot Rust Fly	Aster Leafhopper	European Corn Borer
Kemptville	1378	1378	1172	521	1072	1486	876	783
For reference on the various thresholds, see table at the very bottom of this post.

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Sudbury

Location	Onion Maggot	Seedcorn Maggot	Cabbage Maggot	Leek Moth	Carrot Weevil	Carrot Rust Fly	Aster Leafhopper	European Corn Borer
Sudbury	1212	1212	1020	430	928	1310	751	668
For reference on the various thresholds, see table at the very bottom of this post.

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Thresholds

Use these thresholds as a guide, always confirm insect activity with actual field scouting and trap counts.

Degree Days
	1st generation	2nd generation	3rd generation
Onion Maggot	210	1025	1772
Seedcorn Maggot	200	600	1000
Cabbage Maggot	314-398	847-960	1446-1604
Carrot Rust Fly	329 – 395	1399-1711	n/a
Leak Moth	445	Egg to adult development after two nights of >9°C
Carrot Weevil	138 – 156	Egg laying (oviposition) begins
	455	90% of the egg-laying (oviposition) is complete
Aster Leafhopper	128	Overwintering eggs hatch
	390	Local adult emergence