VCR – Vegetable Crop Report – August 22, 2019

Temperature – Humid and wet conditions in most growing regions earlier this week were conducive for the spread of some plant pathogens. The Durham, Huron, Peterborough, Simcoe, and Sudbury growing regions are still tracking marginally to significantly behind their average degree day accumulation; while the Chatham, Essex, Kemptville, Norfolk and Wellington growing regions have all caught up to their average degree day accumulations.

Rainfall – Precipitation in most areas varied from a quarter inch to more than two inches depending on the growing region in the past week. Norfolk County has already exceeded it’s average rainfall, while Durham, Peterborough, and Wellington are all past the three quarter mark of their average rainfall totals. Remaining growing regions range from under a quarter to the halfway point of their respective rainfall averages.

Crop Updates

Brassica Crops –Alternaria can cause head rot in broccoli and cauliflower if spores are able to infect the beads/curds and secondary bacteria can cause rot. Calcium deficiency causing tip burning has been observed in a few fields. Continue to scout for Alternaria, black rot and fusarium wilt.

Carrot – Harvest is underway for some earlier planted fields. The second generation of Carrot Rust Fly is now active in all growing regions with exception to Chatham-Kent, Essex, Kemptville, and Norfolk. Be on the lookout for white mould between row as canopies are not closed. Continue to monitor for aster yellows, as well as leaf blights which will appear on the oldest leaves at the bottom of the canopy.

Celery – Celery leaf curl has been the predominate pathogen observed. 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. Scout for aphids, bacterial blights and leaf diseases

Garlic – When choosing a field for the 2019-2020 field season, avoid a field that has been planted in garlic, leeks or onions in the last 3 years. There will be another full day workshop in Guelph on December 4th that will cover every part of garlic production including clean seed, cultivar selection, seeding density, nutrient testing, scape removal, weed control, crop insurance, harvesting, grading, storing as well as scouting/pest management. To register, call the Agriculture Information Contact Centre at 1 877-424-1300.

Onions – The pressure of thrips has reached threshold in several regions but the general pressure this season is still low. Stemphylium leaf blight and tipburn is starting to take hold. Early transplants have been harvested in some regions and direct seeded onions are close to lodging in others.

Potatoes – Early planted fields are being harvested with most fields in or past bloom and are currently bulking. Tuber bulking is a critical time for irrigation and soil moisture. Refer to the chart below for yield impacts on dry weather conditions. Remain vigilant in scouting as some varieties begin to senesce. Remember to keep late blight specific fungicides in your spray rotation. Late Blight has been confirmed in New York State on Potatoes. The isolate has been identified as US-23 which is sensitive to Ridomil. If you suspect late blight in your field, please contact Dennis at dennis.vandyk@ontario.ca, (519) 766-5337.

Growth Stage	Soil Available Water Requirement	Yield Losses IF Available Water Below Required Levels
Growth Stage I Sprout Development	75% available soil water	Short periods of drought stress do no reduce yields
Growth Stage II Vegetative Growth	75% available soil water	5%
Growth Stage III Tuber Initiation	80% available soil water	10%
Growth Stage III Tuber Initiation	80% available soil water	10%
Growth Stage IV Tuber Bulking	90% available soil water	40-60% Highest demand for water. Adequate water is necessary for high yield. Dry conditions favour tuber malformations
Growth Stage V Tuber Maturation	60-65% available soil water	Water deficit causes tuber dehydration

Pest Degree Day Forecasting

Pest	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*	1429	1309	976	777	477	1080	1309	685
Chatham-Kent*	1897	1748	1338	1087	721	1470	1748	971
Norfolk**	1832	1689	1290	1047	686	1419	1689	935
Huron***	1595	1460	1084	858	528	1203	1460	753
Wellington**	1605	1473	1099	877	552	1218	1473	776
Simcoe County***	1618	1483	1110	888	564	1228	1483	787
Durham***	1698	1563	1190	970	636	1308	1563	866
Peterborough	1545	1409	1032	804	484	1153	1409	703
Kemptville***	1742	1606	1228	995	644	1350	1606	883
Sudbury***	1429	1309	976	777	477	1080	1309	685