Where is the Sun?

Cool daytime and cold nighttime temperatures prevailed across the Prairies last week. Many areas reported frost on four or five nights with temperatures dipping as low as minus 7^oC in some locations. Soil temperatures remain cool causing seeded crops to germinate and emerge very slowly. The following maps show growing degree days (GDD) that have accumulated thus far:

http://www.agr.gc.ca/pfra/drought/prtgdd_e.htm

In Manitoba, accumulated GDD are compared against a historical average at:

http://www.gov.mb.ca/agriculture/climate/wad00s00/cropwxrep.pdf

The number of days to 50% germination is a useful benchmark as the first half of plants to emerge usually accounts for the majority of crop yield. Research has shown much lower and slower canola germination at low temperatures. Soil temperatures above 5°C have little effect on the time to 50% germination, however the number of days to 50% germination increases dramatically at temperatures below 4°C (with germination taking as long as 9 days at 3°C or over 12 days at 2°C).The following link has more information on how temperature effects canola growth: http://www.canola-council.org/chapter5.aspx#ch5_sec1b