Final Strategic Farming: Field Notes Discussed Late Summer Forage And Small Grains Outlook

Aug 30, 2022

By Phyllis Bongard

As the Strategic Farming: Field Notes summer season wrapped up, small grains harvest, drought-stressed corn for silage, and final alfalfa cutting strategies were topics of this last session. Dr. Craig Sheaffer , Extension forage agronomist, and Jochum Wiersma, Extension small grains specialist, joined moderators Anthony Hanson and Nathan Drewitz, Extension educators, on August 24th to discuss the issues.

Forage update

Outlook

While variability in weather and crop conditions is typical for Minnesota, recent rain patterns have led to good alfalfa regrowth going into the fall. What should growers consider when balancing forage needs against a healthy stand?

Timing final alfalfa cutting

The lowest risk approach for optimizing winterhardiness is to avoid taking any cuttings after the 1st week of September. Because alfalfa depends on a fall dormancy period to prepare for winter, harvest during this critical period between September 7 and October 15 can impact winter survival. If cut during this period, alfalfa would put most of its energy into regrowth, instead of the crucial storage needed for overwintering.
However, if forage is needed, a late fall harvest could be taken between October 15 and early November. This delayed timing minimizes winter injury risks because there is little potential for alfalfa regrowth before a killing freeze.
With a late fall cutting, growers should leave a little more stubble so it can catch snow and protect the alfalfa crowns. If we have a normal winter with snow cover, a harvest at this time should not harm the alfalfa stand.
Can there be problems with too much residue if alfalfa isn’t harvested in late summer or fall? According to Sheaffer, the extra residue is effective at catching snow and the new spring growth will be able to push through it. Nutrients in frosted leaves that fall to the ground can be recycled by the crop the following year. A potential downside, however, is that the old residue stems may lower the quality of the 1st cutting in spring.
Other factors influence how well the crop overwinters. Older stands tend to be more susceptible to winter injury than younger stands. Similarly, lower levels of soil nutrients, particularly potassium, can impact the stand persistence over the winter. He recommends that producers do soil testing to determine if nutrients are needed.
Of course, drying cut forage in the fall is more challenging because of decreasing air temperatures and potential for dew. Field drying times can be reduced by harvesting alfalfa as haylage or baleage instead of making dry hay at 20% moisture or less.
For more information, see Fall cutting alfalfa.

Drought-stressed corn silage

As parts of the state deal with dry conditions, harvesting drought-stressed corn for silage may be an option for salvaging the crop. Keep in mind that recommended moisture levels vary depending on the type of storage, so test moisture content before and during chopping.
Drought-stressed corn can accumulate nitrates, which interfere with function of hemoglobin in the blood stream and can be very harmful to livestock. Harvest strategies to reduce nitrate risks include: raising the cutting bar to leave at least 6” of stubble because nitrate concentrations tend to be highest near the base of the stalk; and delaying harvest for at least 3 days following a soaking rain that comes after a period of dry weather to allow for metabolism of the nitrate within the plant.
Although ensiling can reduce the nitrates in corn silage by as much as 50%, to keep livestock safe, always test suspected forage for nitrate concentration before feeding; high nitrate levels can be diluted with other forages or grains. Silage testing will also provide information about overall nutritive value of the drought-stressed corn which because of less grain fill may have lower energy values.
For more information, see Harvesting drought-stressed corn for silage, Harvesting drought-stressed corn as baleage, and Additional resources for drought-stressed crops.

Small grains update

Outlook

Early small grain yield and quality reports from the Red River Valley are excellent, with some reported yields as high as 80-100 bu/acre. High protein levels have also been reported. They are likely due to an extra flush of carryover N after two dry falls.

When comparing winter and spring wheat yields, winter wheat has about a 20% advantage, since grain fill usually occurs during advantageous cooler temperatures.

Disease

Fusarium head blight (FHB)

FHB models indicated high risk for infection this summer, making Wiersma nervous. However, while he could find scabby kernels in the field, they were relatively few and very small tombstone kernels. These “tombstone” kernels are light, so they can be managed with air on the combine. As a result, there’s little concern for DON this year.

Black point

Black point may cause quality concerns this year, since the discoloration it causes at the kernel’s germ end may be discounted at the elevator. This disease is favored by hot, humid conditions and frequent rain. As the showers continue off and on, black point will continue developing.
If the crop is harvested a little wetter than normal, Wiersma recommends drying it down as quickly as possible to 13.5 – 14% moisture to stop black point development. If time and weather are not cooperating, consider a little supplemental heat.

Ergot

There are more reports of ergot in wheat and barley this season, which is uncommon. The disease is much more common in rye. Cool, wet weather favors the disease, but it can’t infect small grains unless kernels don’t get pollinated. Infection is likely to be the worst on field edges because weedy grasses can be hosts. Wiersma recommends harvesting the field edges separately or letting that part of the field stand until the ergot bodies drop to the soil surface. Because it is a food safety issue, the grading threshold for ergot is low – roughly one ergot body for 2,000 kernels.

Insect pests

Wheat stem sawfly (WSS)

Damage reports suggest that WSS’s area has expanded as far north as the Canadian border. However, the pest is still mostly a nuisance issue, rather than an economic one. If you see severely lodged areas with the telltale razor-cuts on the straw, Wiersma would like to hear from you.

Hessian fly

The major surprise this season has been reports of Hessian fly. This introduced insect pest has not been an issue in Minnesota because it needs a green bridge to survive the winter. Typically, its preferred host is any kind of wheat but our winter wheat acreage is too small to support the level of reports coming in this year.
Why are we seeing this now? There are a couple of scenarios that might fit. First, the Red River Valley has seen two dry falls and not all volunteer wheat stands were destroyed. Some spring wheat individuals have enough winter hardiness to make it through to the next spring, making those individuals potential hosts for the Hessian fly.
Second, winter rye is a host for this pest. Increased acreage of early-planted rye cover crops could serve as the green bridge for the Hessian fly.
Hessian fly can be kept in check if it can’t find an overwintering host. Control volunteer wheat and barley stands before winter cereals are seeded. Winter wheat and winter rye should not be seeded before the “fly-free” dates: September 10-15 in northwestern MN and 3rd week of September in southern Minnesota.