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Alfalfa Evaluation Continues

University of Minnesota Extension, Stearns County News
April 29, 2015

Source:  Dan Martens, Extension Educator
University of Minnesota Extension
Stearns, Benton & Morrison Counties


Alfalfa Evaluation Continues
By Dan Martens, University of Minnesota Extension

FOLEY, Minn. (04/24/15) — Alfalfa growers and agronomy advisors will continue to evaluate alfalfa stands, maybe even through the month of May. During the next week to 10 days, with some warmer weather hopefully, we’ll be able to tell more clearly whether fields are moving forward or backward. Farmers might see during first crop harvest that some fields are not in good shape; and may plant corn or another crop after taking the first cutting of alfalfa. We may see some problems with some grass hay crops too.

Plants damaged by cold winter weather, sometimes show deterioration in roots after warmer weather arrives and plants have to be able to take up water and nutrients to support more growth. Buds set in the fall may be killed; and then takes time to start new buds. Wet weather last spring and dry weather late in the summer and fall might have added stress on some alfalfa fields.

You can do an Internet search for “Minnesota Extension Forage Quarterly Spring 2015” to find a lot of information about evaluating alfalfa winter injury, alfalfa establishment, alfalfa grass mix, alfalfa herbicides, aphanomyces, and insect issues. And you’re welcome to call the County Extension office for this information as well. In Stearns County call 255-6169 if a local call to St. Cloud or 1-800-450-6171; in Benton call 96805077 if a local call to Foley or 800-964-4929; and in Morrison call 632-0161 if a local call to Little Falls or 1-866-401-1111.

I’ll work here with discussion offered recently by Wisconsin Extension Forage Specialist Dan Undersander about strategies to consider for problem fields depending on conditions and feed needs.

Interseeding. If a small or moderate percentage of the field is affected and you want to harvest forage from the existing stand, go over the affected area with a drill seeding 10 pounds per acre with a 50/50 mix of Italian and perennial ryegrass to a depth of ½ inch. A no-till drill might be used if a regular drill doesn’t provide adequate seed depth. This might be useful where there is general thinning of stands across the field, but enough alfalfa to be worth keeping. These grasses will likely not contribute much to a normal first cutting, but should contribute nicely to second and following cuttings. Italian ryegrass will grow later into the fall better than most grasses – as long as moisture is suitable. It will not survive winter. Italian ryegrass can be interseeded alone as well.

Allow plants to mature longer before cutting. Letting stressed fields go to early bloom or later can give them some chance to restore roots. Stands with only mild injury could be allowed to go to 10 to 25% bloom sometime during the season. It may be best to choose second or third cutting with these stands as first crop is usually the largest. It is difficult to figure out whether fields can recover enough to work with this way. Feed quality as well as quantity needs are certainly a factor.

If letting fields go to bloom, cutting higher might be important. New shoots may be developing at the base of the plants. It is important to not remove these shoots as it will further weaken the plant to have to start over again. 

Fertilize. It is particularly important that winter injured stands have adequate fertility. Soil test and apply needed fertilizer prior when field conditions are suitable.

No Late Cutting. Do not cut winter injured stands after Sept 1 to allow for the buildup of food reserves prior to winter. Dry weather during late summer may have hampered fall regrowth last year.

I’ll add that this year, we’re dealing with this early enough in the season to consider many possibilities. Corn will make good use of nitrogen left behind by a terminated alfalfa field. Corn for silage offers the best opportunity to produce a lot of feed for cattle, even when planted well into June. BMR Sorghums and other forages can be considered for livestock that don’t need all the grain we usually get in corn silage.

Where farmers try to salvage damaged fields, it’s good at the same time to get some new fields started as soon as practical. We often can’t bank on damaged fields to recover greatly for the future.

Please make SAFETY a priority in all your spring work discussions. 

(PHOTO CAPTION) The split alfalfa root on the left shows some brown decay in the center of the root that is not unusual for a 4 year old plant. There is plenty of white, firm heathy tissue and good growth that has already started. The root on the right shows small, meager shoots that probably started last fall. This root feels soft and mushy and would be brown and stringy on the inside when split. Damage fields will show a wide range of conditions.


Daniel Martens
Extension Educator, Ag Production Systems
(320) 968-5077
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