Fall Armyworm Awareness

By Samantha Daniel

In previous years, portions of eastern Nebraska have seen unprecedented numbers of fall armyworm caterpillars feeding on alfalfa, brome regrowth in pastures, and newly seeded small grain crops such as wheat, triticale and rye. While reports of armyworm damage have not been received so far this year, it is a good idea to keep an eye out for this insect.

Fall armyworm caterpillars can be distinguished from other Lepidopterans by markings on the head that resemble an inverted “Y” and four spots on the last abdominal segment that form a square. This insect does not overwinter in Nebraska, but rather migrates north from southern states when populations build up in late summer. Once caterpillars are ¾-inch, they can do considerable damage in a few days. Because of this, it is important to scout fields and pastures in the early morning and late afternoon, when caterpillars are most active, to spot them when they are small.

A reasonable treatment threshold is finding three or more caterpillars per square foot within a field or pasture. There are several insecticides labeled to control this insect, including Mustang Maxx, Besiege, and Sevin. For forage crops, be sure to check the grazing restriction and post-harvest interval. When considering a chemical treatment option, keep in mind caterpillars ¾-inch or longer are close to maturity and can be harder to control with an insecticide.

Fall armyworm feeding declines with cooler temperatures and the adult moths eventually migrate south. In the meantime, plan to keep an eye on your pastures and newly seeded fields for any sign of infestation.

Late Summer Pasture Weeds

By Jerry Volesky

August always seems to be a time when certain weeds can become quite noticeable in pastures. There can be a variety of common annual weeds like sunflowers, lambsquarters or kochia.

Perennial weeds like western ragweed, ironweed and verbena can be plentiful in some pastures as well. In areas of pastures that have relatively thin grass stands, in areas where animals congregate, or if some overgrazing has occurred, they can be very visible.

Spraying weeds now does little good. Many weeds are too large to kill. On both annual and perennial species that produce seed, herbicides might only reduce some seed production. If the goal is to improve appearance, shredding areas that have an abundance of weeds might be the best option, and may reduce some seed production too, if it’s not already too late.

Two other approaches are better for long-term weed control. First, focus on the grazing management of your pastures. This includes using the proper stocking rate and developing a good rotational grazing plan. An important objective is to increase the health, vigor and density of your grass. Healthy, competitive grass stands are essential to reduce weed populations economically over time.

Second, target herbicide applications for when they will do the most good. Both perennial and annual species can be better targeted with a spring application when plants are smaller and able to be controlled. For perennials, if a second application is needed, waiting closer to a killing frost is best. These fall applications can be more effective as more product is translocated down to the roots of the weeds.

Pasture weeds may look unsightly now but hold off on spraying. Improve grazing management and time herbicides for the best window of control so herbicides won’t be needed as often in the future. On the bright side, for areas that have had good rains this summer, it is likely that annual weeds will be less abundant next year as pasture grasses had a chance for buildup vigor and reproduce.

Corn Silage Harvest

By Ben Beckman

Silage harvest for fully irrigated full-season corn usually begins 45 days or 800 GDDs after the tassel/silking growth stage. However, growing conditions and the season length of the plant itself can make predictions based on the calendar fuzzy at best.

Accurately assessing whole plant moisture is key to proper silage pile fermentation and tight packing. If silage is too dry, packing is difficult and may allow oxygen into the pile, causing overheating, mold/yeast/bad microbe growth, and spoilage. When the silage moisture content is too high, piles can weep with valuable energy and nutrients flowing out as a loss from the pile. Also, damaging clostridia bacteria colonies can grow when silage is too wet. So, target silage storage moisture content should be 65-70% moisture.

Another factor to consider for silage chopping is milk line (a corn kernel starch content indicator). Starch is one of the most energy dense feed components, so silage that contains higher amounts of starch will be higher energy overall. The further down the kernel milk line is established, the more starch content has been stored in the kernel.

Plant moisture and milk line may not be directly correlated and may vary among hybrids. While these development factors trend in the same direction, the moisture content may vary from field to field, even if milk line is the same.

Corn silage is a great feed resource that can benefit from moisture content monitoring at harvest. Target harvesting silage at 65-70% moisture content for best results. Use the ear kernel milk line (closer to the cob means more starch and higher energy silage) to find your ideal harvest window based on your hybrids.

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