Temperature – Many regions are below the 10-year average accumulated degree day average so far this year. Sudbury has had just over half the growing degree days compared to the 10-year average while Huron, Wellington, Chatham-Kent and Simcoe County are marginally ahead.
Rainfall – Most regions have had above average rainfall in March and April and many are on track to also exceed the average rainfall in May. Precipitation levels shown in the charts below for 2019 show the precipitation up to May 15th compared to the total monthly average of the previous 10-years. Excess precipitation has delayed seeding across many areas of Ontario. Continuous rainfall and cool temperatures have not allowed many fields a chance to dry out.
Brassica Crops – Cool temperatures and wet conditions have delayed transplanting across most areas of Ontario. This non-ideal weather has slowed plant growth and wet conditions have been conducive for damping off pathogens such as Pythium or Fusarium. Nights where temperatures have reached close to freezing have resulted in some blocks with tip dieback. Cool temperatures have resulted in slower development of insect pests. The degree day threshold for cabbage maggot emergence has not been reached in all areas of the province.
Carrots – Carrot planting is delayed with some early acres seeded. Insect pressure is low at this time.
Celery – Transplanting has been delayed in many areas and in fields that have been transplanted growth is slowed.
Garlic – Lack of snow cover during cold winter weather and repeated freeze-thaw cycles in the early spring may have led to a higher amount of winterkill in some fields compared to other years. With the wide range of growing degree days across the province, many fields are between the 2nd leaf and 8th leaf stage. Overwintering leek moth adults have been detected in traps in Southwestern Ontario. At a threshold of 7 °C, leek moth requires approximately 445 degree days to develop from egg to adult ((Max Temp + Min Temp)/2) – 7°C. Accumulation of degree days starts one week following peak flight of male moths captured in pheromone traps, and is reset to zero for each generation. Degree days have been reached for the first generation of seedcorn maggot in Essex, Chatham-Kent and Norfolk counties; dig up wilted/stunted plants and scout for maggots or feeding damage.
Onion – Direct seeded onions and transplants have had a late start and some direct seeded onions have emerged but growth has been slowed. Agricorp has extended the onion planting date for onions given the wet weather. Seed onion planting date of May 15th will be extended to May 22nd and the Spanish onion planting date of May 20th will be extended to May 27th. The first generation of onion and seedcorn maggot flies are active in Essex and Chatham-Kent County; dig up wilted/stunted plants and scout for maggots or feeding damage.
Potatoes – Potato planting has also been impacted by the cool and wet spring. Be wary of emergence issues and seed rots when planting into cold and wet ground. If you’re using cut seed, allow it to suberize/heal before planting, especially if you’re also using a liquid seed treatment.
Pest Degree Day Forecasting
Select a region below for the latest weather, crop and pest degree day information:
|Pest||Carrot Rust Fly||Onion Maggot||Carrot Weevil||Aster Leafhopper||Tarnished Plant Bug||Cabbage Maggot||Seedcorn Maggot|
Use these thresholds as a guide, always confirm insect activity with actual field scouting and trap counts.