Time to make the cover crop switch

Anne Verhallen, Soil Management Specialist – Horticulture, OMAFRA, Ridgetown

Colder days and frosty nights are a strong signal to make the change in cover crop plantings. October is too late to continue planting oats, barley or oilseed radish – any growth won’t be worth the expense. While it takes at least a –4°C freeze to kill an established oilseed radish, as the temperatures fall, cover crop growth will slow and younger plants are more sensitive to cold injury. Oats and barley will usually die out earlier than OSR.  One exception is mustard. Young mustard plants often can survive the winter and will have the jump for growth in the spring – this can pose a problem if early planting is planned.

It is time to switch to winter wheat, rye or even triticale. Rye will germinate at 1 to 2°C and slowly grow at 4°C. That explains the late planted rye that goes into the winter looking like green wisps across the field and by spring covers the field in a blanket of green growth. Timely planting of winter cereals will ensure good ground cover – if the ground is bare now, don’t wait!  Get it covered to get the most out of your cover crop dollar!

Late planted oilseed radish – growth by mid October – probably not worth the cost
Late planted oilseed radish – growth by mid October – probably not worth the cost
Oat and oilseed radish cover crop planted in August; growth by mid October
Oat and oilseed radish cover crop planted in August; growth by mid October

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