VCR – Vegetable Crop Report – May 14, 2020

Temperature – Growing Degree Day values lag far behind the 10 year average in all regions and many had very little accumulation in the past week. Frost stress has been reported in many regions which have already began planting. Warmer temperatures expected in the upcoming week across Ontario may help values catch up. Temperatures have still not yet been warm enough to trigger pest forecasting thresholds for any regions (a possible exception being leek moth emergence in some southern portions of the province). Degree day data for each region is shown below.

Rainfall – While all regions are significantly behind the half way mark for their 10-year averages, rainfall is forecasted for all regions over the course of the next week. Thunderstorm warnings have already sprung up today for the southern portion of the province in Essex, Chatham-Kent, and Norfolk counties. Precipitation data for each region is shown below.

Crop Updates

Asparagus – Cold temperatures have kept emergence slow, frost has damaged emerged spears.

Brassica Crops – Most transplants are showing frost damage across the province with the outer most leaves turning yellow. While it has not been warm enough for seedcorn or cabbage maggot fly to reach it’s first generation growing degree threshold for Essex or Norfolk counties, it is likely present in some protected areas or microclimates.

Carrots – Early planted carrots have struggled through the recent frost events. Soil-borne diseases remain a concern with the low soil temperatures during taproot development. Be mindful that most pre-emerge herbicides are more effective in cooler temperatures and could cause increased crop injury. See the recent article from Kristen Obeid on the topic.

Cucurbit Crops – Register now for the online Cucurbit IPM Scouting workshop for Thursday, May 20^th.

Garlic – Hard frosts have caused damage and most plants are showing some sort of tipburn. Most plants have reached the 5th leaf stage so avoid applying nitrogen to reduce the amount of rough bulbs at harvest. Leek moths were active the week before last but night temperatures have been low this past week. Dig up stunted or wilted plants in the field. Maggot fly larvae or wireworms cause a lot of early season damage (pictures of each below). If your garlic already shows leaf damage due to an insect, please send photos to travis.cranmer@ontario.ca.

garlic-seedcorn — Stunted garlic plant with Delia maggot fly larvae – May 14, 2020

garlic-wireworm — Wireworm identified at the base of a stunted garlic plant – May 14, 2020

Onions – These cold nights have made it difficult for transplants to establish. Despite the cooler weather, seeded onions are at the loop stage in many regions.

onion-loop — Direct seeded cooking onions at the loop stage – May 13, 2020

Potatoes – Emerged potatoes suffered frost damage over the weekend. Many acres have been planted in the last week and a half so hopefully the seed pieces remained safe from any frost layer.

Rhubarb – Wilted stalks from frost damage should be removed.

Sweet Corn, Beans and Peas – Register now for the online Sweet Corn, Beans and Peas IPM Scouting workshop for Friday, May 15^th.

NOTE: Data as of May 13th, 2020

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*	244	191	78	41	13	109	191	29
Chatham-Kent*	188	141	54	26	3	75	141	17
Norfolk**	194	149	53	25	2	76	149	15
Huron***	123	93	37	17	0	50	93	9
Wellington**	121	85	26	9	0	39	85	4
Simcoe County***	115	81	26	9	0	40	81	4
Durham***	147	109	36	16	1	52	109	9
Peterborough	124	87	26	8	0	39	87	4
Kemptville***	133	97	28	11	1	42	97	6
Sudbury***	46	30	5	1	0	9	30	0