By Robert Burns
Bermuda grass stem maggot advances across Texas
After a year of low activity, the Bermuda grass stem maggot has returned with a vengeance and spread quickly across Texas.
“Since 2013, this new pest has rapidly expanded its range in Texas and is now found throughout much of East, Central and South Texas, and as far west as Abilene and San Antonio,” said Dr. Allen Knutson, Texas A&M AgriLife Extension Service entomologist, Dallas.
There have also been reports of the pest even farther west in the Brownwood and Anson areas, said Charles Allen, AgriLife Extension entomologist, San Angelo.
The presence of the pest was first confirmed in Texas in Van Zandt County in 2013, but was relatively inactive in 2014, Knutson said.
“Unlike other insects that attack plants from the outside, the Bermuda grass stem maggot damages them from inside,” said Dr. Vanessa Corriher-Olson, AgriLife Extension forage specialist, Overton.
“Basically, they consume material inside the stem, unlike armyworms or grasshoppers, where the damage is external,” she said.
As the pest is still relatively new to Texas, most farmers and ranchers may not recognize the early signs of damage by the maggot.
“Damage is first evident as the top two or three leaves turn white or brown, but the remainder of the plant remains green,” Knutson said. “The top dead leaves are easily pulled from the stem. Infested fields may appear ‘frosted.’”
Management recommendations developed in Georgia and Alabama suggest that if damage is found, the best course of action is to harvest the crop as soon as possible, Corriher-Olson said.
“Once the damage becomes apparent, the crop is unlikely to add a significant amount of yield if left to further develop,” Corriher-Olson said. “The damaged crop should be cut and baled and removed from the field as soon as weather conditions allow. Leaving the damaged crop in the field will only compete with any attempts by the plant to regrow and decrease the opportunity that the next cutting will have time to accumulate dry matter.”
Knutson said maggots feeding within the stem will die once the crop is cut and dried for harvest.
“However, without treatment, flies will emerge from pupae in the soil and re-infest the field,” he said. “To protect the regrowth from infestation, apply a pyrethroid insecticide about seven days after cutting hay to kill adult flies. A single application is usually sufficient. There are yet no effective methods for sampling Bermuda grass stem maggot fly or larvae or guidelines for when an insecticide treatment is needed.”
AgriLife Extension district reporters compiled the following summaries:
Central: Soil moisture, rangeland and pastures, crops and livestock were all in good condition. Though with dry conditions and higher temperatures, pastures grasses were beginning to brown. With the hotter weather, producers were cutting and baling hay. Dairy producers were chopping silage and seeing high yields. Brush control was ongoing. Cattle were in good condition. Grass growth remained good. Grains sorghum was about harvest-ready. Corn was highly variable in maturity, even within the same field. Sugarcane aphids were present but not at economic thresholds for spraying. As populations grow, producers expected to start spraying in the next week or two.
Coastal Bend: Soil moisture was dropping, and pastures were declining due to another week of hot, dry windy weather. Producers were going full tilt harvesting corn and grain sorghum. Yields of both corn and sorghum were good so far, but harvest will be strung out due to the unusually wet conditions earlier this year that resulting varying maturity within fields. Cotton and soybeans needed moisture. Fly problems on cattle increased, but otherwise cattle were in great condition. Hay production was good.
East: Hot weather and high winds were drying up soil moisture around the region. Small stock pond levels were dropping because of evaporation. Pastures in upland sites were showing signs of dryness and drought stress, while grass in low-lying areas and river bottoms looked good. Hay yields were higher than normal. Some producers noted that once hay was cut, it was not growing back. Other producers were taking a second cutting. Quality varied widely. Producers continued shredding and spraying to control weeds. They were also on the lookout for armyworms and preparing to spray for grasshoppers. Bermuda grass stem maggots were found in Wood County. The fruit and vegetable harvests were underway. Watermelons were doing extremely well with record-breaking yields. Tomatoes and peas suffered from the drier conditions. Cattle were in good condition. The hot and dry conditions were keeping cattle near ponds or under trees for a good part of the day. Producers continued to sell market-ready calves and cull cows. Feral hogs were active.
Far West: All counties had highs in the upper-90s to above 100. Cotton was doing well in El Paso, Glasscock, Pecos and Upton counties. The watermelon harvest was in full swing in Upton County. Livestock in all counties were doing extremely well due to abundant grass in pastures and rangeland.
North: Topsoil moisture was mostly adequate with a few shortages reported. Daytime highs were in the mid-90s and nights in the mid-70s with no rain – a normal summertime weather pattern for the region. The wheat harvest was all but over. A few producers were trying to harvest late-planted fields. Yields on the late-planted fields were very low, about 10 bushels per acre. Corn and grain sorghum were behind schedule because they too were planted late. The crops were in about average condition otherwise. Pastures and warm-season grasses looked very good for this time of year, and hay production was in full swing. Livestock were in good condition, enjoying the new grass growth. Lakes and stock-water tanks were still full. Insect populations were rising. There were early reports of sugarcane aphid in sorghum sudan.
Panhandle: Early in the reporting period, the weather was hot, dry and humid, then isolated storms from mid- to late-week brought moisture and hail to some areas. Soil moisture continued to be mostly adequate. Grasshoppers were a problem throughout the region, and many producers had to spray and shred grass and weeds in field corners for control. The hot, dry conditions added some much-needed heat units to cotton. In Collingsworth County, some wheat fields were still too wet to harvest, and the crop likely will be plowed under once farmers are able to get in with machinery. Ponds and stock-water tanks in pastures were still full, and cattle were thriving. In Dallam and Hartley counties, producers were finishing harvesting wheat. Where there was no hail damage, yields of irrigated fields ranged from 70 to 100 bushels per acre. Producers there were irrigating corn as the crop was just starting to tassel. The third cutting of alfalfa was underway. Without much wind again this week, windmills weren’t pumping, so water had to be hauled to cattle in some areas. Rangeland grasses were mostly green, though some areas were beginning to get pretty dry. In Deaf Smith County, crop adjusters were assessing the damage done to the corn, wheat and sunflowers from last week’s storms. Wheat harvesting restarted where producers were able to get combines into fields, with dryland fields averaging 35 to 70 bushels per acre and irrigated fields from 40 to 80 bushels per acre. Except for southwestern corn borer, insect pressure was light. In Hansford County, the wheat harvest wound down. Storms passed around Hutchinson County, and producers had to start heavily irrigating. Ochiltree County was hot and dry, but crops looked excellent with all of the previous moisture. There were still a few wheat fields left to be harvested. Some fields had to be abandoned due to weeds. Most corn was behind schedule; otherwise the crop was in excellent condition. The few cotton fields that survived the spring rains were delayed in development. Sherman County had received 14.94 inches of rain for the year, and early planted corn looked fantastic, but the late-planted crop had some catching up to do.
South: Conditions were drying out throughout the region as temperatures continued to rise. Humidity was rising as well, though little rain fell in the last week. In the northern part of the region, rangeland and pasture grasses were beginning to turn light in color quite rapidly. Producers continued to cut and bale hay. Peanuts and cotton under irrigation were developing well. Corn and grain sorghum were beginning to mature. Soil moisture was adequate in most of the northern counties, except for McMullen County, where it was short. In the eastern part of the region, corn and grain sorghum were progressing well, and cotton was in fair to good condition. Producers continued to provide supplemental hay and protein to livestock. Soil moisture was adequate in Jim Hogg and Jim Wells counties. Kleberg and Kenedy counties had 100 percent surplus subsoil moisture and 50 percent adequate topsoil moisture. In the western part of the region, growers finished harvesting watermelons. In Maverick County, most forage crops were harvested, except for some corn and sorghum. In Zavala County, hot and dry conditions required producers to actively irrigate cotton, grain sorghum, corn and sunflowers. Sorghum harvesting was ongoing. Pecans were progressing well with no reports of second-generation case bearer infestations. Rangeland and pastures were in fair condition. Soil moisture was adequate in Dimmit and Maverick counties, and 100 percent short to very short in Zavala County. In the southern part of the region, sugarcane, grain sorghum and corn harvesting were in full swing in Hidalgo County. Irrigation of cotton was also active. In Starr County, producers were preparing to harvest grain sorghum and corn. Pastures were beginning to show signs of heat stress. Soil moisture was adequate in the Hidalgo and Starr counties.
South Plains: The region had warmer temperatures and drier weather with clear skies. Cotton farmers received much needed heat units to help the crop mature, but the crop was still about three weeks behind schedule. Producers hoped there wouldn’t be an early freeze this year. Grain crops were in excellent shape. Some Swisher County producers had to start irrigating. Corn and grain sorghum were in excellent condition with some sorghum beginning to head. At least one scouted field contained a 30 percent coverage population of sugarcane aphid colonies. In Crosby County, many producers were putting out plant growth regulators and battling weed problems. Lubbock County cotton was squaring. Corn was in the tasseling to milk stage. Sorghum ranged from four true leaves to pollinating. Field operations included herbicide and plant growth regulators.
Southeast: Soil moisture throughout the region varied widely, but was mostly adequate to short, with short being the most common. Galveston County reported 100 percent short levels. Rangeland and pasture ratings were mostly fair to good, with good ratings being the most common. Most of the region had high temperatures and dry weather. In Fort Bend County, the sorghum harvest was well underway, with corn harvest expected to follow soon.
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