Widespread alfalfa winterkill being reported
|By Mike Rankin, Managing Editor
Name any Upper Midwest state and there’s a good chance widespread alfalfa winterkill is being discussed.
Although no year is a good year to be looking at brown alfalfa fields in the spring, the timing for this year is especially bad with wet conditions severely delaying spring field activities and the dairy economy still reeling from an extended period of low milk prices.
By now, most alfalfa growers have been able to assess the damage, which ranges from complete loss to only portions of fields. I’ve heard about situations where the high spots were dead from not holding snow cover and others where the low spots had killed, presumably from being under ice and water for an extended period of time.
The decision of whether to keep the stand or issue “last rites” is not always easy.
“In fields where stand loss is patchy, decisions whether to keep the stand should be based on the health of the remaining plants and the total area lost,” says Kim Cassida, Michigan State University’s extension forage agronomist.
“In fields with more than 50 percent alfalfa loss, starting over may be the best bet. Fields with less than 50 percent alfalfa loss and more than 30 percent healthy plants in the surviving sections may be worth salvaging for a year or two by interseeding with another forage to fill in the gaps,” she adds in a recent MSU Extension News report.
Fixing the dead patches
If you’re stuck with some dead areas in an otherwise productive alfalfa stand, it is possible to bring those areas back to life, just not with alfalfa unless the field was a new seeding from last year.
Alfalfa is autotoxic; planted seed will not develop into healthy and productive plants where alfalfa is currently growing close by or where it was recently grown. Most forage agronomists suggest waiting at least six months but preferably a year before seeding alfalfa back into a previous alfalfa field.
Although it’s rarely successful to interseed alfalfa into alfalfa, selecting other forage species to help fill the dead or thin areas is a viable alternative.
“Interseeding with red clover at 6 to 10 pounds per acre or Italian ryegrass at 5 to 10 pounds per acre can prolong the useful life of a damaged alfalfa stand by up to two years,” notes Cassida. “These two options are good for producers who harvest their forage primarily as chopped haylage, but they are difficult to dry as hay.”
The forage agronomist further explains that small grains and annual cool-season grasses such as oats, wheat, rye, or triticale seeded at 50 to 75 pounds per acre, or annual ryegrass at 5 to 10 pounds per acre, can provide high-quality forage quickly, extending stand life for one year.
When selecting annual or Italian ryegrass, Cassida offers this caution: “Use care to prevent seed set because these grasses may readily develop glyphosate resistance and can potentially become weed problems when a field is subsequently rotated to corn or wheat.”
For alfalfa stands with less severe winterkill or injury, interseeding a perennial forage grass is an option that some producers do on a routine basis. Orchardgrass or tall fescue generally work the best and will provide multiple years of productivity. They also will take longer to establish.
To help ensure seeding success, Cassida recommends using a no-till drill. Large, dead patches can be disked first and then seeded.
“Broadcast overseeding is unlikely to give satisfactory results unless it can be done in March as a frost-seeding,” Cassida says.
Where extended wet conditions have prohibited getting into fields and the alfalfa growth is already tall, Cassida suggests waiting until after first cutting to interseed fields. This approach will result in less competition for the new seedlings.