Forage options for drought-stressed corn

By Mary Drewnoski - Beef Systems Specialist; Ben Beckman - Extension Educator; Jenny Rees - Extension Educator

There have been a number of questions on non-irrigated drought-stressed fields and their potential use for forage. For nonirrigated pivot corners, it probably doesn’t make a lot of sense to use them for forage unless they’re larger areas or forage is needed. Leaving those plants can help with soil erosion too. Corn condition varies throughout the D3 and D4 drought-designated portions of the state, with some corn in the D4 area that is 5-11 leaf and mid-calf to below waist high in height.

Grazing Restrictions: When considering taking drought-stressed corn for forage, first check herbicide labels for any grazing restrictions. Pictures of the forage and feed restrictions from the 2023 Guide for Weed, Disease, and Insect Management can be found at the end of this article.

Crop Insurance: If it’s OK to use the corn for forage, then contact crop insurance. This is an important step as failure to do so can impact the APH assessed to that field for the next 10 years. For corn prior to pollination, stand reduction or permanent wilt loss methods can be used for assessment. The charts will not show much loss for stand reduction. For permanent wilt, the information in the Corn Loss Adjustment Standards Handbook shares about corn plants firing, lower leaves easily crumbling in one’s hands, corn that doesn’t unroll in the evenings and that doesn’t respond to moisture.

Once the crop is released by crop insurance and you’ve waited the period for any restrictions regarding using the corn for forage, the corn can be used for forage. The following are options for consideration.

then energy would be more beneficial by feeding a little grain. We’re all learning in this so please share what you observe if you try supplementing with grain, hay, or both.

Silage: This really depends on plant height and ability to harvest for silage. Dr. Bruce Anderson shared in a 2012 CropWatch article Using Weather Damaged Corn as Forage that, “Fermentation usually (but not always) reduces nitrate levels and risk. Yield is about one ton per acre of silage for each harvested foot of earless corn plant (not counting the tassel). Feeding value is about 70% to 80% of well-eared corn silage. Corn with some grain (less than 50 bushels) tends to produce about one ton of silage for every five bushels of grain with a feed value about 80 to 90% of regular corn silage. Harvest timing is critical with silage to ensure the correct moisture for proper fermentation. Desired moisture level for silage is about 65%. Plants with any green leaves usually are too wet to chop for silage. For proper moisture, most leaves may need to be dead before chopping. The stalk and ear hold amazingly high water concentrations. For corn with no grain, even if all leaves are dead, the whole plant (and silage) moisture can be 70% if the stalk is still green and alive.

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Grazing: Grazing is one of the better and perhaps more realistic options with as short as this corn is. Yes, there will be nitrates. We aren’t as concerned about grazing corn higher in nitrates prior to ear development compared to if the grazing would occur after an ear was put on. Protein is higher when grazing corn in these vegetative stages. Some keys are to not turn livestock out empty. Providing plenty of fresh water will help reduce nitrate risk. Cattle should self-adapt by eating the tops of plants first and then will be more adapted to eating the higher nitrate areas lower in the plant. While it may be tempting to cross fence and graze as much of the plant as possible (which is what we recommend when grazing corn with ears), in this current situation with no ears, strip grazing will reduce the time animals have to adapt to higher nitrates. Thus, we recommend open access to the field to let animals be more selective and reduce exposure to parts of the plant with potentially toxic nitrate loads.

Some may desire to supplement hay to reduce risk of nitrate poisoning. We’re unsure if it’s necessary and if the cattle would eat it when grazing corn in vegetative stages. The thought is if risk abatement is the idea,

Once plants actually die they can rapidly dry down. There are several ways to reduce moisture content. If corn has pollinated, delay silage harvest until all chances of increased biomass tonnage have passed or plants naturally dry down to appropriate moisture levels. Corn can be windrowed and allowed to partially dry before chopping. Excessively wet material can be blended with drier feeds such as ground hay, cracked grain, or dried distillers grains. However, this can take a lot of material — about 500 lb of grain or hay to reduce each ton of chopped corn with 85% moisture down to 70% moisture. Silage inoculants may improve fermentation and preservation of drought-damaged silage.”

Chopping: Chopping is an option to help with reducing nitrates, but really depends on corn height and inability to fence for decisions if one wants to run equipment through it. If feeding green chop, feed immediately after harvest and only feed the amount that the animals will consume in two hours. If green chop is left in the bunk or on the wagon, it can heat up and nitrate will be converted to nitrite. Nitrite is 10 times as toxic as nitrate when fed to animals. Therefore, it is better to feed green chop two to three times a day to ensure that it is cleaned up quickly and not left sitting.

Haying: Haying would be the last option, as it has twice the nitrate risk of grazing. For haying, we’d recommend taking nitrate samples after the hay is baled so you have a better idea on the levels you’re dealing with.

Blister beetles in hay are a danger for livestock

Blister beetles have made their appearance in North Dakota and are feeding on alfalfa fields.

“The name ‘blister beetle’ stems from a naturally occurring toxin called cantharidin produced by the beetle that causes blistering of skin when the beetle is crushed and the toxin is released,” says James Rogers, Extension forage crops production specialist at North Dakota State University’s North Central Research Extension Center.

Adult blister beetles are attracted to blooming alfalfa fields and weeds (goldenrods, dandelions). They will feed on nectar and pollen and devour leaves, stems and flowers. Blister beetles produce one generation per year and will be active from June to September. Adult blister beetles will lay their eggs in soil from late summer to early fall and can overwinter in North Dakota as larvae, emerging in mid to early summer.

Cantharidin from blister beetles can cause severe inflammation and even death in horses, says Rogers. In horses, depression, inflammation and ulceration of the mouth, irritation of the gastrointestinal tract, and painful urination are common symptoms of sub-lethal doses of cantharidin. Cattle and sheep are much more tolerant of cantharidin ingestion. Little work has been done to establish toxicity levels, though symptoms can occur with cantharidin ingestion. These symptoms may include depression, elevated temperatures and dehydration.

The most common species of blister beetles found in North Dakota are the ashgray and black blister beetle. Lesser seen are the striped and Nuttall’s blister beetle. Blister beetle toxicity levels are higher in males but also vary by species and by the region in which the beetles are found, says Rogers. Adults range in size from ½ inch to 1 inch long. Blister beetles are fairly easy to identify among other beetles, as the “neck” region located behind the head is narrower than the head when viewed from above.

Blister beetles are very mobile and tend to swarm in large numbers in small areas of the field, says Miranda Meehan, NDSU Extension livestock environmental stewardship specialist. They can move into alfalfa fields from field edges that have a host plant such as sweet clover, which blooms earlier than alfalfa. Once alfalfa begins to bloom, they may move into a field and feed for a short period of time before migrating to other areas of the field or to new fields. After alfalfa is cut, they often move into blooming canola and other blooming field crops. Hay infested with blister beetles is a big concern for hay producers and livestock owners.

Here are some ways to reduce the threat of blister beetles:

Use equipment such as a disc mower without hay conditioners or crimpers that may crush blister beetles and release toxin into the hay. This also encourages beetles to move out of the hay field.

Allow cut hay to fully dry before raking to allow beetles to move out of the hay. Raking may dislodge dead beetles from hay; however, the potential still exists for cantharidin in the hay.

Control blooming weed hosts near or in alfalfa fields.

Cut alfalfa at less than 10% bloom and/ or late in the season (mid-August to early September).

Check fields 24 hours prior to cutting to ensure that new swarms of blister beetles have not re-infested the fields.

Scout harvested hay and underneath windrows closely for blister beetles and allow blister beetles to move out of drying hay before baling. Turning the windrows may be helpful to get blister beetles to move out.

“Even tractor tires can crush blister beetles in hay when turning equipment around,” says Karl Hoppe, Extension livestock systems specialist at NDSU’s Carrington Research Extension Center. “Cut hay with a sickle bar or disc mower that allows blister beetles to move out of hay after cutting. If large numbers of blister beetles are observed in spots during harvesting, it is best to quit

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