Anne Verhallen, Soil Management Specialist
Rye cover crops have certainly benefited from the cool temperatures and frequent rains. Early seeded rye is well over 10 to 12 inches while even the later seeded covers from November are starting to stretch.
With good growth on cover crops come concerns about controlling them. Options for controlling overwintered wheat and rye cover crops this spring:
- Tillage – A light discing will knock the growth back but won’t kill the cover crop consistently across the field. A good option if you want to keep scattered plants for wind abatement.
- Herbicides – Glyphosate is usually the product of choice for cover crop control. Look in the OMAFRA Publication 75, Guide to Weed Control (pg 79) Preplant Site Preparation Prior to Any Crop. The recommended rate of glyphosate active is 0.27 to 4.32 kg/ha. Rates used to control overwintered cover crops will depend upon the growth/tillering of the cover crop. Ensure that the cover crop is actively growing. Allow 5-7 days translocation time after application before doing any tillage if growing conditions are good. If conditions are cool following application, allow additional time for translocation to occur. Table 4-3 Glyphosate Products and Their Registered Uses in OMAFRA Publication 75, Guide to Weed Control (pg 59) gives some different glyphosate options.
- Effect on the cover crop – Higher rates of glyphosate will give a more rapid kill but will also tend to knock the cover crop flat. To assist wet soils in drying out it may be more effective to apply a slightly lighter rate in order to keep the cover crop upright and allow for air movement across the soil surface.
| Cover Crop – species/growth | Product Rate per acre (adjust based upon actual product used) |
| Winter wheat – well tillered | 2+ L/acre |
| Winter rye – well tillered, overall field cover crop | 1+ L/acre (at 6 inch height)
Increase the rate with increasing growth stage and rye height. |
| Winter rye planted as wind strips (for wind abatement, the goal is to keep the rye standing, so a slow kill is desired) or other locations where a standing killed cover is desirable | 0.5+ L/acre if rye is 6 inch in height or less
Increase the rate as the rye height increases. 1+ L/acre if the rye is 12 inches in height |
- Rolling and crimping – This is a system used by some growers like Steve Groff of Pennsylvania. The cover crop has to be at the boot stage or fully headed out to get good control by just breaking stalks. Better to combine this with a herbicide application if possible.