Avoid Alfalfa Winter Injury - Next Time

April 30, 2009
ICM News

By Stephen Barnhart, Department of Agronomy

There have been reports of localized areas of winterkill and winter injury to forage and winter cereal grain crops this past winter in Iowa.  

The reports indicate damage on sites across the state, but the most extensive areas are in northeast Iowa.  There are reports of damage to alfalfa, orchardgrass, perennial ryegrass, winter wheat and winter triticale.

Most of the affected stand damage is either in low spots where ice and standing water were the main problems; or on hilltops with snow cover loss and exposure to cold and crown damage, or associated localized ice sheeting. The injury is often worse in old alfalfa stands,where established hay stands were harvested or grazed in late fall, or new forage or cereal grains were planted late in the fall season.

By now most producers have inspected and either reseeded or over seeded forage stands.

While the risk of winter injury is with us every year, producers can consider some risk reducing management practices in the future.

• Select alfalfa varieties with Fall Dormancy index scores of 3 and 4, and Winter Survival Index scores of 2 to 3.5 (or lower).

• Orchardgrass is a grass species with moderate winterhardiness, so expect occasional winter injury. Select orchardgrass varieties that are well adapted to your location, and avoid varieties from unknown origins or adaptation.

• Perennial ryegrass is a high quality and useful forage grass, but it has less consistent winter survival in Iowa than orchardgrass. While there are some perennial ryegrass varieties with improved winter survival, avoid including it as a high proportion of a forage mixture or consider it in regular oversowing practice. And don't count on an initial ryegrass seeding to be a long-term component in your stands.

• Plant late-summer forage seedings and 'winter-cereals' (rye, winter wheat and winter triticale) fields during the planting periods recommended for your area.

• Avoid harvesting or grazing alfalfa stands during the fall and early winter.

Stephen K. Barnhart is a professor of agronomy with extension, teaching, and research responsibilities in forage production and management. Barnhart can be contacted at (515) 294-7835 or by email sbarnhar@iastate.edu.


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