TYLER, Texas (KETK) – Armyworms, which are usually active in the fall, can be devastating to the hayfields and pastures they feed from. But the worms have yet to make their appearance.
Recent weather conditions have not allowed for migration patterns that led to past devastation from the worms, according to David Kerns, Ph.D., AgriLife Extension state integrated pest management specialist and professor in the Department of Entomology.
“Fall armyworms typically build up in southeastern Texas, and the moths move northward throughout the eastern half of the state,” Kerns said. “Last year, with all the spring and summer rains, that buildup occurred earlier than usual, but conditions are much drier this year despite the recent storm fronts.”
According to Kerns, armyworm populations typically build following large rain and cool weather events, but there are no current populations building in the southern areas of the state.
Armyworms active season is typically between July and September when their populations become damaging to forage production.
Texas A&M AgriLife Extension Service provided the following additional information:
No reports of armyworms so far
Fall armyworms are green with brown or black colorations and can be identified by the white inverted Y on their head. They can grow up to 1 inch in length when mature.
The pest got its name because they appear to march army-like across hay fields, consuming the grass in their path.
Armyworm moths can lay up to 2,000 eggs that hatch in two to three days, according to a 2019 report by Allen Knutson, Ph.D., AgriLife Extension entomologist, retired.
Vanessa Corriher-Olson, Ph.D., AgriLife Extension forage specialist, Overton, said there are four to five generations that move throughout the state per growing season. They typically move north from Mexico and South Texas as temperatures warm in the spring. Generations will push further north into midwestern states, but moths and larvae remain present throughout the state.
Drier, hotter conditions slow their life cycles, Corriher-Olson said. Moths lay fewer eggs and caterpillar growth is slowed. But rainfall and cooler temperatures can trigger major infestations when local populations, new hatches and migrating moths descend on areas with quality food sources.
Corriher-Olson said continued drier conditions overall in southern parts of the state are likely to curb any early issues forage producers may have experienced in 2021.
“I have not received any reports or phone calls, and that tells me populations in areas where the armyworm migration begins have not reached any level of concern,” she said.
No problem until there is a problem
Corriher-Olson said producers typically react to fall armyworm outbreaks when they occur, which has led to product availability issues during the pandemic. She noted, however, that she had not received any reports about insecticide shortages to date.
“Many producers take a reactionary approach to armyworms because of the expense,” she said. “Some producers may have products on hand that are left over from last year, but most are going to be monitoring the situation to their south and plan accordingly.”
Kerns said conditions may not be shaping up for armyworms at this point in the forage production season, but producers with Sudan grass, hay grazer and other forages related to sorghum should be on the lookout for sorghum aphids, also known as sugarcane aphids.
While armyworms prefer wetter, cooler weather, sorghum aphids prefer hot, dry conditions, he said. There have been reports of the aphids in grain sorghum fields in South Texas.
Aphids feed on leaves and leave a sap that further damages the plant, and major infestations can greatly impact forage yields.
Corriher-Olson said forage pests like fall armyworms and aphids are always a threat to producers’ bottom lines, but yield losses could magnify their impact on budgets due to higher input costs, especially fertilizer applications.
Many forage producers are forgoing or reducing fertilizer applications, which could impact where infestations build, she said. Fall armyworms will settle on any green pasture, but they prefer lush, fertilized forages.
“Fertilized fields are more at risk to be damaged,” she said. “So, when it comes to armyworms, we don’t want to see a producer spend money to produce quality forage and have armyworms destroy it.”