Alfalfa Winter Injury and Wet Ground – What Do We Do Now?

photo of damaged alfalfa

Many alfalfa fields in northeastern Indiana suffered serious winter injury. Statewide, alfalfa weevil damage was more common this year and control was difficult because of persistent spring rain. Timely forage seeding of perennial legumes and cool-season grasses this spring was not possible because of excessive rain. Continued rainfall has limited the ability to make hay on a timely fashion and forage quality will be compromised. A result of all of these concerns is that forage supplies in the Midwest USA will likely be reduced in 2019. Producers need to carefully consider all options to meet forage needs if winter injury and waterlogged soils reduced forage yield and quality.

Some corn and soybean producers may opt to take a prevented planting payment if they have crop insurance and all stipulations regarding prevented planting are met. This acreage can be seeded with a crop that can be harvested as a forage after November 1. I am seeking clarification with a Risk Management Agency employee to confirm if the forage can be harvested as chopped silage or baleage, or whether the harvest can only be grazed or packaged as hay.

What follows are some comments that should be useful as individuals make decisions about alfalfa stands, crop choices that could provide emergency forage if alfalfa stands are poor, and what seeding options one might consider if a prevented planting payment is received and there is an interest in harvesting the crop as a forage after November 1.

It is very important that communication with the crop insurance representative occurs before possible plans are put into action. It is prudent for producers to speak with Farm Service Agency personnel, too, about the impact the late winter and spring has had on yield and quality of all forages, not just alfalfa.

Alfalfa Field Assessment and Forage Seeding Considerations

Greater than 35 robust stems per square foot is a minimum threshold for an economic alfalfa stand. Even if the stand is poor, consider taking a harvest as hay supply will be limited.

Evaluate the severity of heaved alfalfa crowns and taproots.

Dig plants and examine root and crown health. Cut taproots in cross and longitudinal sections and note whether roots are mushy or streaked with much disease.

If it is decided that harvest should occur, harvest above heaved alfalfa crowns.

Scout the alfalfa on a weekly schedule to determine whether more stand is lost because of heaving or disease.

Harvest high, greater than four inches, if the first harvest of alfalfa has not been cut as second growth is occurring, too. Delayed regrowth will occur if cut too low.

If the stand is acceptable, does fertilizer need to be supplied as determined by soil test? If so, apply recommended nutrients after the forage has been removed from the field. If the forage stand is yellow, it likely is a nitrogen deficiency caused by a waterlogged anaerobic soil. Fifty pounds of N per acre may be in order if root health is good. If a sandy and low organic matter soil is present and the alfalfa is yellow, it could be a sulfur and/or boron deficiency. These deficiencies are best analyzed with a tissue test.

If the alfalfa stand is marginal and termination will occur, it is best to not reestablish back to alfalfa until next spring. Alfalfa autotoxicity (allelopathy) can occur when a new alfalfa seeding immediately follows an alfalfa stand. Removing the forage reduces the amount of toxin. The zone of influence of an established plant upon seedlngs is approximately a very large dinner plate. If the stand is extremely poor because of winter loss, an August reseeding may be successful if the stand is terminated soon. Details about alfalfa autotoxicity can be found at the link https://www.extension.purdue.edu/extmedia/AY/AY-324-W.pdf

Terminate alfalfa with tillage or herbicides that will control alfalfa and reduce summer-annual weed growth. Review herbicide labels to note what crops can be seeded without injury and if the crops can be harvested as a forage. Is the alfalfa Roundup Ready variety?

Forage crop choice to follow alfalfa if sown in late spring

    • Seed company personnel indicate that there is very limited sorghum or millet crops in inventory. Seed representatives should be contacted immediately if this is the preferred forage crop. Sorghum and millet seed production was low in 2018 because of weather-related conditions.
    • Late-maturity indeterminate soybean (one selected that will not make grain) would be a viable option for an excellent quality forage.
      • Cut as a silage before soybeans are in the green bean stage and no leaf yellowing.
      • Drill soybeans.
      • Date of harvest would likely be in September or early October.
    • Teff
      • Moderate quality at best.
      • Hay is best method of harvest.
      • Very firm seedbed needed.
      • Seed at 1/8 inch.
    • Forage crabgrass
      • Can be grazed or hayed.
      • Volunteer crabgrass is likely if allowed to go to seed.

 

Forage crop choice to follow alfalfa if sown in early August

  • Spring oats
    • Best harvested as silage; drying would likely be difficult if packaged as hay in October.
    • Excellent quality.
    • Option – Include forage turnips with spring oats if pastured and more energy is desired.
  • Annual ryegrass for grazing (can overwinter)
    • Beware – Purdue University weed scientists and many industry weed scientists express concern about terminating annual ryegrass with a herbicide. Annual ryegrass is more difficult to kill than small grains and when growth is late vegetative or older.
    • Excellent quality.
    • Not a good choice if wheat grain is in the crop rotation because of volunteer ryegrass.
    • Include magnesium in mineral mix to reduce chance of grass tetany.

Fall seeding (early October)

  • Could follow all crops above with a winter small grain seeding (cereal winter rye, winter wheat and winter triticale) that could be harvested as a forage in spring 2020.

 

Prevented Planting Payment eligible with forage crop opportunity – At the date of this information (June 4), it was verbally communicated by a Risk Management Agency employee at a public meeting that the forage can be grazed or mechanically harvest as hay, but not harvested as chopped silage or baleage. Confirmation to whether hay harvest is the only means of mechanical harvest is being requested.

Immediate harvest on Prevented Planting Payment corn acreage – If cereal winter rye and winter wheat are cover crops growing now, they have value as a moderate quality forage if harvested when the developing seed is before or at the milk stage. Labels of herbicides used on the 2018 crop, as well as the small grain cover crop, need to be evaluated to see if the small grain can be used as a forage. Before harvesting the small grain cover crop, the crop insurance agency representative should be advised of the intention to use it as a forage.

 

Forage crops seeded for after November 1 use

Forage crop choice if sown in mid-August

  • Spring oats
    • Drying would likely be difficult if packaged as hay.
    • Excellent quality.
    • Option – Include forage turnips with spring oats if grazed and more energy is desired.
    • Will not overwinter.
  • Winter small grains (cereal winter rye, winter wheat and winter triticale) for fall grazing
    • Include magnesium in mineral mix to reduce chance of grass tetany.
    • Will overwinter and could be harvested in the spring, too.
  • Annual ryegrass for fall grazing
    • Beware – Purdue University weed scientists and many industry weed scientists express concern about terminating annual ryegrass with a herbicide. Annual ryegrass is more difficult to kill than small grains and when growth is late vegetative or older.
    • Excellent quality.
    • Not a good choice if wheat grain is in the crop rotation because of volunteer ryegrass.
    • Include magnesium in mineral mix to reduce chance of grass tetany.
    • Can overwinter and if it does, could be harvested in the spring, too.
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