By Adam Russell
Forage producers around the state are battling fall armyworms and taking protective measures to defend high value pastures and fields for hay and grazing, according to Texas A&M AgriLife Extension Service experts.
David Kerns, Ph.D., AgriLife Extension’s statewide integrated pest management coordinator and associate department head for the Texas A&M Department of Entomology, said he’s seen reports about spotty outbreaks of fall armyworms in parts of Texas earlier than usual. He said the localized nature of those infestations in rice fields and improved pastures like Bermuda grass suggests environmental conditions were right for populations to flare up.
When it comes to armyworms, Kerns said every year is different, but population spikes and the potential for infestations are directly linked to rainfall.
“Outbreaks are always tied to precipitation,” he said. “Wet weather during the summer promotes grass growth in the landscape, and healthy pastures provide habitat for their populations to build.”
In recent weeks, however, AgriLife Extension agents in counties around the state have reported fall armyworms in standing pasture, early winter wheat fields and landscapes. Forage and cattle producers are monitoring their numbers closely or initiating control regimens.
Damage to standing forages and emerging wheat has been reported from North and East Texas to the Coastal Bend and the South Plains regions.
Fall armyworms on the march
Fall armyworms are extremely damaging to forages and got their name because they appear to march army-like across hay fields, consuming the grass in their path.
Vanessa Corriher-Olson, Ph.D., AgriLife Extension forage specialist in the Texas A&M Department of Soil and Crop Sciences, Overton, said she has been busier than usual fielding calls and holding presentations for producers at the request of AgriLife Extension agents who are receiving calls. She highly recommends producers who value forages to be on alert and prepared to initiate control regimens.
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 1.5 inches in length when mature.
Fall armyworm moths can lay up to 2,000 eggs that hatch in two to three days, according to a 2021 report, “Fall Armyworm Control in Pastures (PDF),” by AgriLife Extension entomologists.
The pest’s name is also indicative of its active season, and activity typically begins to increase between July and September, Kerns said. The pest can persist until frost.
Whether producers hope to make one more cutting of warm-season hay or establish good stands of cool-season forages like ryegrass or winter wheat, Corriher-Olson said they should be ready to act against fall armyworms as soon as the pests near threshold.
She recommends producers scout for fall armyworms in the morning.
Armyworm presence may be evident in emerging winter forages, but in taller forage canopies. Kerns recommends using a canvas drag net to sweep through the standing grass in multiple locations in each field or pasture.
“Scouting for armyworms should be a part of your daily routine, especially if you have standing forage that you will be relying on for winter feeding and grazing,” Corriher-Olson said.
Be on the lookout, stay prepared
Corriher-Olson said some forages may need more attention than others.
“There is a lot of overseeding to be done and young winter wheat and ryegrass out there now,” she said. “Those seedling annuals are much more sensitive to fall armyworm damage than our warm-season perennials. If Bermuda grass is eaten, it can bounce back, but if those fledgling winter annuals that are a few inches tall are eaten back to the root before they’re well-established, you’re likely going to need to replant.”
Producers with high-value irrigated forages should consider fall armyworms a constant threat because the consistent moisture creates the right conditions for population booms, Corriher-Olson said.
Kerns said pyrethroid-based pesticide applications are typically the go-to control method because they are low cost, but they are not 100% effective, especially when armyworm populations are high. Pyrethroids don’t last long on the crop they protect, and rain can wash the spray away.
For longer residual control he recommends a mix of pyrethroid and products with the active ingredient diflubenzuron or chlorantraniliprole. Diflubenzuron will not work on bigger worms, but its residual sticks around and will knock back younger caterpillars and hatchlings. Products with chlorantraniliprole offer long residual control of all sizes of worms and is rainfast. Other products containing methoxyfenozide will provide moderate residual control but are susceptible to washing off during rainfall.
“Mixing products is just a good strategy, especially under high pressure,” Kerns said. “That may also be a good strategy to defend early stands of winter wheat and ryegrass between now and the first frost.”
AgriLife Extension district reporters compiled the following summaries:
Central
Daytime temperatures remained high, while nighttime temperatures were cooler with no rain reported. Bermuda grass growth slowed. Soil moisture decreased, and stock tank levels declined. Earlier-maturing varieties of pecans were harvested. The peanut harvest was two weeks ahead of schedule, and irrigated fields looked excellent. Sunny conditions allowed cool-season forages to be planted and germinated, but some planted oats were becoming stressed due to the lack of moisture. Some plowing continued, but soil moisture was decreasing rapidly. Cotton harvest continued with reports of 2.5 bales per acre on average and some fields with higher yields. There was an increase in fall armyworm activity. Livestock were in good condition, and producers began feeding hay as grazing declined. There was some concern from ranchers that beef cattle inventory may drop further this fall due to increased drought conditions, the La Niña weather pattern and high beef prices.
Rolling Plains
Conditions across the district remained dry, and some producers were considering when to plant winter wheat. Some planting was done after spotty rains last week, but soil levels quickly turned dry with day-time highs in the 90-degree range. Some producers were holding off on planting until rain comes while others were moving forward with dry planting with the hope for rain soon. Despite the dry conditions, most livestock appeared to be in good shape, with some ranchers starting to feed hay and supplements.
Coastal Bend
Weather continued to be hot with scattered thunderstorms at the end of the week. Soil moisture levels were declining, and pastures were drying quickly. Rain was needed for grass growth, and minimal winter annual pasture was expected to be planted this year due to dry soil conditions and decent to abundant hay supplies. Fieldwork continued with stalk destruction, disking and bedding, along with some hay baling. Pecan crop estimates were poor. Livestock were doing well, with fall calves hitting the ground in good condition. Cattle prices remained strong.
East
Low humidity and high winds dried out the soil, and rainfall was desperately needed. Pond and creek levels were lower. Pasture and rangeland conditions were fair. Subsoil and topsoil conditions were short to adequate. Some producers were holding off on planting winter pastures for now. Hay production continued as producers tried to get one more cutting. Armyworm infestations were still a problem. Livestock were in fair to good condition with some supplementation taking place. Horse flies were more prominent.
Southeast
Rain was needed as drought conditions continued to worsen. Soil moisture levels were very short to adequate. Some cattle producers began to provide supplemental feed. Cotton continued to be defoliated in some areas and was being harvested in others. Summer forage growth slowed, and winter pasture forages were being planted but needed rain to establish. Counties were implementing burn bans until further notice. Producers were cutting and baling their last hay harvest. Rangeland and pasture conditions were poor to excellent. The rice harvest continued.
South Plains
Subsoil and topsoil moisture levels were short. Cotton harvest was getting underway, and more fields were being sprayed and prepped for harvest. The hot days helped mature the cotton crop. Most of the corn was harvested, and producers were starting to dig peanuts. Cattle, rangeland and pastures were in good condition.
Panhandle
The weather was hot, dry and windy. Harvest of feed grain and forage crops continued. Most cotton fields had reached 65% or more open bolls, and some growers started applying harvest aids to expedite harvest. Others were allowing more time for maturity of upper canopy bolls. Emergence of early planted small grain crops appeared to be making good progress with expanding leaf width and length dimensions contributing to canopy that was quickly filling space between seed rows. Improvements in soil moisture would help germination and emergence. Rangeland and pastures were going dormant. Overall soil moisture was very short to adequate. Pasture and range conditions were very poor to fair, and crop conditions were poor to good.
North
Pasture and range conditions were reported very poor to fair. The subsoil and topsoil were very short to adequate, and no rain was observed in the district. Drought conditions continued to stress all vegetation. Temperatures were into the 90s and cooled during the night dropping to the 60s. Trees and summer grass conditions continued to decline. Livestock on supplemental feed were faring well while body conditions were declining on grazing alone. Some wheat and cool-season grasses were planted in the hopes of rainfall soon. Activity of horn flies, millers, fall armyworm and grasshoppers was reported.
Far West
Temperatures were in the mid-to-high 90s during the day, with lows in the upper 60s at night. No precipitation was reported. Most days were suitable for fieldwork. Subsoil moisture levels were very short to short while topsoil moisture levels were short to adequate. Cotton bolls were open in the southeastern parts of the district, and cotton yields were not optimistic in the more northern areas. The cotton fields were being defoliated and harvest will start shortly. Conditions were too dry to plant wheat and oats. Producers continued to feed livestock and wildlife. Most pastures and rangelands were very poor to poor.
West Central
Days were warm, and conditions were drying. Producers were planting wheat and oats, and some early planted fields were germinating well. Pasture and rangeland conditions were fair to good, but warm-season grass growth was slowing due to drought. Hay cutting and baling continued, and bales were in good supply. Armyworm and grasshopper damage continued to be an issue for forage producers and ranchers. Producers continued to work fall cattle. Cotton fields in some areas looked good, but others were not progressing well due to extreme heat in previous months, and some fields failed. Pecan harvest was underway.
Southwest
Daytime temperatures reached the low-90s, and no rainfall was reported. Cooler nighttime temperatures were in the low-60s. Rangeland and pasture conditions were deteriorating. High soil temperatures delayed cool-season grass seed germination. Some planting of winter pastures and wheat was delayed due to extremely dry conditions, but some farmers were dusting in oats and hoping for rain. The pecan harvest was expected to begin soon as the nuts matured. The cotton harvest should conclude soon. Livestock conditions remained fair to good, with animals relying on supplemental feed and seeking shade during the day. Whitetail deer were active and seeking water, but few migratory birds were observed. Rams and bucks were turned in for the breeding season.
South
Conditions remained dry across many counties while some areas received between 0.5-3 inches of rainfall. Lake levels were at all-time lows, and many irrigation districts were out of water. Temperatures were hot in most areas. Peanut and sesame harvests will begin soon. Forage producers were making a final cutting of hay on irrigated fields. Strawberry growers were awaiting plant deliveries. Cotton harvest continued. Farmers began to plant leafy greens and winter wheat. Citrus trees were doing well, and fruit continued to mature with harvesting underway in some locations. Growers were monitoring reports of increased fruit fly activity. A few fall-planted corn fields were showing signs of moisture stress while others looked good. Pastures and rangelands looked drought-stressed and continued to decline in areas without rainfall while areas with rainfall were fair to good and greening up. Some overgrazed pastures were still lagging in recovery. Armyworms continued to persist on pastures, but some areas experienced declining populations. Ranchers continued to supplement livestock diets with feed. Livestock and wildlife were in good condition. Beef cattle markets reported average sale volumes with a slight increase in feeder cattle prices, while demand for cull cows/bulls and replacement cattle remained high. Beef prices fell slightly at some sale barns. Many landowners were making final preparations for deer hunting as deer and quail conditions and numbers were excellent this year.
Source : tamu.edu