Armyworms plaguing pastures, winter forages

By Adam Russell

OVERTON – Cool temperatures and wet weather created prime conditions for fall armyworms and major problems for forage producers around the state, said a Texas A&M AgriLife Extension Service expert.
Dr. Vanessa Corriher-Olson, AgriLife Extension forage specialist, Overton, said the recent temperature drops and rainfall across much of the state after a dry, warmer September and October created conditions for the pest to emerge.
This has been especially hard on emerging cool-season annual forage fields, she said.
Recent crop reports from county agents around the state describe producers treating fields for armyworms, high numbers of the pest and devastated forage fields. Planting of winter forages were also delayed by infestations, and some producers were forced to replant decimated fields.
“The biggest issue has been on cool-season forage fields,” she said. “Armyworms prefer the highest quality forage available, so at this point they’ll pick the cool-season annuals over the warm-season perennials. When you have seedlings coming up, they can devastate a field overnight.”
Corriher-Olson said producers who planted fields for grazing or forage production should scout pastures regularly, especially if temperatures cool or rain and cool temperatures follow a warm, dry spell.
Producers should scout each morning for armyworms, she said. Armyworms are night feeders that try to avoid warmer daytime temperatures.
Armyworms are green, brown or black and can be identified by the white inverted Y on their heads. They can grow up to 1 inch in length.
The threshold for insecticide spray treating a pasture is three or more armyworms per square foot, Corriher-Olson said. Armyworms in those numbers should be treated immediately.
Armyworms in the last two or three days of their larvae stage consume 85 percent of their diet.
The pest got its name because groups appear to march across hay fields, consuming the grass in their path.
“Some producers get caught off guard because there is a misconception that if you spray warm-season pastures for armyworms earlier in the year that it takes care of them,” she said. “That’s not the case. When conditions are right, they emerge. And right now, conditions are right, and they are showing up around the state. So, if you have a pasture that has value to your operation, scout regularly and be prepared to apply pesticides immediately.”
AgriLife Extension district reporters compiled the following summaries:
CENTRAL: Cooler temperatures arrived and caused pasture conditions to deteriorate. Heavy winds and light frost were reported in some areas. Rains slowed the cotton harvest. Corn harvest was almost complete. Some farmers replanted small grains due to armyworm damage. Pecan harvest was underway on early varieties. Pecan yields and quality looked good in managed orchards. More moisture was needed for winter wheat. Livestock were in good to moderate condition. Most counties reported good soil moisture and overall rangeland and pasture conditions. Nearly all counties reported good crop conditions.
ROLLING PLAINS: Pasture conditions declined and wheat fields were replanted due to armyworm infestations. A recent cold spell helped knocked armyworms back a little. The cotton harvest started, and wheat planting was finishing up. Weather conditions ranged from hot to freezing. A freeze was enough to kill much of the cotton acreage, so harvest should begin very soon. Soil moisture was holding well. Cattle were on supplemental feed as pastures fell short.
COASTAL BEND: Pecan harvest was in full swing with fair yields reported due to high winds from Hurricane Harvey. Winter pastures were beginning to stress from low moisture. Field work resumed with drier conditions, and hay fields were being cut and baled. Livestock were in good condition.
EAST: Cool temperatures across the district brought moisture to many counties with Angelina, Harrison and Shelby reporting over 1 inch of rainfall. Pasture and rangeland conditions were fair in most counties apart from Marion County where conditions were good. Producers in Cherokee, Henderson, Marion, Upshur and Wood counties started feeding hay to livestock. Some producers in Wood County received enough moisture to plant winter pastures. Panola County producers who planted cool-season forages reported them emerging. Jasper County reported good growing conditions. Subsoil and topsoil conditions in the district were short with the exception of Newton, San Augustine and Tyler counties, which reported adequate conditions. Livestock conditions were good with cattle still dropping calves. High numbers and prices were seen at sale barns. Damages from wild pigs were reported in Cherokee, Henderson, Shelby and Wood counties.
SOUTH PLAINS: Subsoil and topsoil moisture levels on the South Plains continued to dry out. The first freeze was reported. Defoliants were applied to cotton, and harvest was well underway. Yields were average to above average so far. Most sorghum across the region was mature, and about half of fields were harvested. Most wheat had emerged and continued to mature. Pest problems were nonexistent. Pasture and rangeland remained in fair to good condition. Cattle were doing well.
PANHANDLE: Conditions were dry across the district with near-average temperatures. Soil moisture was mostly adequate. Cotton maturation continued, but a lingering freeze may stop progress. Late-planted cotton could be in trouble. Harvest continued on cotton and peanuts. Cattle may need supplemental feed soon to maintain body scores. The corn harvest in Lipscomb County was almost complete, and cotton harvest was just getting started. Ochiltree County corn, sorghum and cotton harvests were going full speed ahead. Freezing temperatures on consecutive nights were enough to finish growth of all crops. Damage estimates due to the freeze were expected to be low. Rangeland and pastures were near full dormancy. Cattle were being placed on wheat pasture. Baling and grazing of some corn and sorghum stalks were beginning after the freeze.
NORTH: Topsoil and subsoil moisture levels ranged from mostly adequate to short, with some counties reporting very short. There were 1-1.5 inches of rain reported but not enough to make a major difference. Temperatures ranged from warm during the day to close to freezing in the evening. The change in weather patterns caused some stress to the livestock. Cotton and wheat harvests continued. Farmers in Pilot Point and Celina reported their best cotton crops, producing 8 bales per acre. Soybean harvest was near completion. Pastures were showing signs of stress and stock ponds continued to shrink. Cattle were doing well, and the spring calves were weaning off nicely. The cattle market was up and continued to look good. Wild pig activity was moderate. Fall armyworms were reported in some of the pastures in the counties.
FAR WEST: No report was provided.
WEST CENTRAL: Weather conditions were seasonable. Temperatures were mild with colder mornings. A light freeze and frost were reported in many areas. Dry, windy conditions continued to dry out soil moisture. All areas needed rain. Conditions forced some counties to reinstate burn bans. Stock tank water levels continued to decline. Some were at critical levels. Winter wheat was in poor to fair condition due to lack of moisture and insect problems. Armyworms were still plaguing crop. Some producers have sprayed two to three times already. Cooler temperatures should help with control. Some producers replanted wheat fields. Small grains planting continued. Most cotton fields were sprayed with defoliant, and harvest was underway with good yields reported. Rangeland and pastures were in good shape going into the fall season. Livestock remained in fair to good condition. Pecan harvest was in full gear.
SOUTHEAST: Livestock were in good condition. Winter pastures were coming along well, especially following recent rains. Warm-season grasses were beginning to shut down. Most row crop producers were nearing the end of field work. Walker County received rain with the weekend cold front. Most areas received 1 inch or less of rain. Pastures were still drying, but forages received enough moisture to maintain conditions. Brazos County received a frost across most of the county. In Montgomery County, winter annuals planting was slow. High temperatures and no moisture delayed planting activity. Cooler weather and chance of rain should move planting forward. A light freeze occurred. Livestock appeared to be in good condition overall. Soil-moisture levels ranged widely from adequate to very short with adequate being most common. Rangeland and pasture ratings ranged from excellent to very poor with fair ratings being most common.
SOUTHWEST: Counties reported much cooler temperatures, even freezing or below freezing temperatures. Even with cooler temperatures, county conditions were dry and in need of rain. Rangeland and pasture conditions declined due to colder temperatures. Many fields were still being invaded by armyworms and some farmers lost entire fields. Livestock conditions remained good despite cooler temperatures.
SOUTH: Temperatures were cooler with dry conditions and short moisture levels across much of the district. Soil moisture was adequate in southern portions of the district, but declining in some areas. Jim Wells County reported forage conditions had declined so far due to dry conditions that may indicate a tough winter for cattle producers. Some rainfall and adequate moisture levels were reported in the southernmost part of the district. In Starr County, rangeland and pastures continued to improve from recent rainfall. Peanut harvest was underway, and producers were working on getting their last hay cutting. Armyworms slowed down in some areas. Wheat planting slowed due to an increase in armyworm activity in others. Oat and wheat producers were monitoring the situation and considering replanting or going ahead with an initial planting. Pasture and rangeland conditions were fair to good. Body condition scores on cattle remained fair to good. Brooks County reported October cattle price trends were up, and there were over 1,400 head marketed at the sales barn. Live Oak County experienced its first killing freeze. All vegetable crops were harvested in western portions of the district and farmers were preparing soil for next season. The only remaining crop was Coastal Bermuda grass on irrigated land, which was already heading toward dormancy. A substantial cold front swept through Zavala County bringing temperatures slightly below 40 and creating ideal growing conditions for spinach, cabbage, onions and cool-season grasses and small grains. Native rangeland and pastures continued to be mostly good to fair and to provide adequate grazing for livestock. The spinach harvest in Zavala County was 10 days out. In Hidalgo County, sugarcane harvest was underway and vegetables continued to be planted. The early citrus harvest was slowly starting.

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