Katelyn Kesheimer, an Alabama Cooperative Extension System entomologist, said this was one of the heaviest fall armyworm infestations people have seen in decades.

“I have heard from senior entomologists that the state has not seen anything like this since the 1970s, so 2021 is definitely one for the history books,” Kesheimer said.

There were many elements that led to this massive infestation. The biggest factor was the perfect storm of environmental conditions. These conditions allowed armyworms to not only survive the winter but to thrive once warm weather arrived.

“The mild winter we experienced meant that these cold-blooded insects got off to an early start to begin their migrations,” Kesheimer said. “We had excessive storm activity, which aided the adult moth migration throughout the United States.”

Producers Caught Off Guard

Fall armyworms are a consistent pest that producers see each year. However, the size and early arrival of the infestations came out of left field, catching many off guard. This hampered a producer’s ability to effectively control the population.

The supply of insecticides took a major hit, leaving many people scrambling to find alternative control methods. Even when they could find insecticides, Kesheimer said excessive rainfall in Alabama prevented growers from accessing their fields to treat. This led to more caterpillars surviving to adulthood, where they reproduced and added to the next generation.

“Many producers are used to fall armyworms on a yearly basis. However, this year they were overwhelmed with the sheer number and timing of the infestations,” Kesheimer said. “Because the infestations were so widespread, some producers were unable to purchase insecticides and had to just let the worms eat their grass.”

The Damage

Kim Mullenix, an Alabama Extension beef systems specialist, said the infestations caused widespread damage for Alabama producers.

“Significant fall armyworm damage across the state severely limited yield potential or completely prevented one or more hay cuttings for many producers,” Mullenix said.

Kesheimer said the damage continued into the fall growing season. Those planting winter annuals had to account for the armyworm infestations, which is generally unheard of.

Financially, it is difficult to put a dollar amount on the damage experienced. In addition to forage loss, some producers had to purchase a more expensive pesticide because of the chemical shortage in some areas.

Extension professionals are currently taking survey data to provide a better scope of some of the losses that producers experienced.

Damage Recovery

Because of the amount of damage that was experienced, Mullenix recommends that producers assess their forage stands in the spring.

“Spring is often a good time of year to make management adjustments that can help favor pasture health and more persistent forages,” Mullenix said. “Walk the pastures and hayfields to conduct a visual assessment of how persistent your perennial forages are following the armyworm damage.”

If the stand appears to be thinning, or has permanent damage from the fall armyworm pressures, producers can contact their local Alabama Extension animal science and forage regional agent to discuss a management plan.

Dealing with Limited Hay Supplies

Mullenix said producers saw adequate rainfall throughout the summer. However, the mid-to-late season fall armyworms damage may leave some producers with limited hay supplies.

“Producers should plan for their winter feeding needs now,” Mullenix said. “This includes estimating the length of their typical hay feeding season and the number of hay bales they will need during the winter for the cattle herd.”

If producers discover gaps in their hay supply, there are several strategies that can bring the animals through the winter. Mullenix said one strategy is planting cool-season annual forages.

“This strategy provides high-quality forage to livestock during the winter,” Mullenix said. “Feeding hay and limit-grazing the cool-season forages simultaneously can help extend the forage supply and meet the supplemental nutrition needs of livestock.”

Supplementation

Producers may also need to provide some sort of daily or reduced-frequency supplementation to their livestock.

For daily supplementation, producers commonly use commercial feed blends or byproduct feedstuffs as winter feed supplements. These feed blends generally contain a combination of energy and protein. Producers can use them as a supplement to low-to-moderate quality forages.

Providing a supplement on a less frequent basis can be a better option from a labor standpoint. Producers will often feed a supplement every other day, or at another defined frequency, to reduce the time spent supplementing.

Mullenix said some feedstuffs are more suited for less frequent feeding than others.

“Low-starch feeds­–which contain a more digestible fiber like soyhulls and corn gluten–may be an option for feeding every other day without altering animal performance when fed with moderate-quality hay,” Mullenix said. “When high-starch feeds, such as corn, are fed infrequently, this causes disruption of forage intake and digestibility.”

More information on supplementation strategies is available in the Alabama Extension content piece Supplementation Strategies for Cow Herds During the Winter.

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