It’s not too late to control sugarcane aphids on northeast Texas sorghum fields, but it will be very soon, according to a Texas A&M AgriLife Extension Service expert.
“The aphids just showed up here in northeast Texas the last week to 10 days,” said Dr. Allen Knutson, AgriLife Extension entomologist, Dallas. “Now is the time to be scouting fields for the aphid.”
AgriLife Extension has been tracking the insect since infestations developed this spring in the lower Rio Grande Valley, Knutson said. The pest soon moved northward to Corpus Christi, and then onto the Blacklands region by early June.
The insect poses a new and potentially devastating danger to sorghum fields, he said. Until just recently, its activity was confined to sugarcane and sorghum in tropical and subtropical regions of the world.
“It became a pest of sorghum for the first time in Texas in 2013,” Knutson said. The same year, outbreaks occurred in South and East Texas, Louisiana, Oklahoma and Missouri.
Last year, the pest showed up in northeast Texas grain sorghum fields too late to cause much damage, he said. But this year, it’s coming much earlier and poses a much greater threat to the crop.
Sugarcane aphids are a light green and somewhat yellowish in color, Knutson said. “It’s very tiny; a colony the size of nickel will typically be comprised of 30 or 40 individual aphids.
“It’s relatively easy to recognize because it’s found in very large numbers, and because of the sticky honeydew it secretes,” he said. “It’s unlike any of the other aphids we have in sorghum.”
The honeydew is a clear, shiny material, similar to what pecan aphids produce on tree leaves, according to Knutson.
“Walking into the field, you’ll probably notice the honeydew first because it’ll stick to your clothes and your hands. Turning over the leaves, you’ll see the aphids,” he said.
Damage results from aphids feeding on plant sap, he said. The fed-upon leaves discolor, turning yellow, red, and brown. Extensive leaf injury can greatly reduce grain yield. The honeydew poses a risk to harvest machinery.
“Last year, sorghum producers had difficulty harvesting sorghum as the honeydew coated leaves and gummed up augers on combines,” Knutson said.
Initial colonies the size of a nickel can quickly increase to thousands of aphids per leaf.
“Infestations can increase very rapidly, so fields should be inspected every three to four days to determine if an insecticide treatment is needed.”
To date, there have not been any economic treatment thresholds established by research.
“AgriLife Extension’s proposed threshold at this time is to apply an insecticide when at least 30 to 40 percent of the plants in a field are infested with sugarcane aphids,” he said. “An infested plant is one with at least one aphid colony–an adult plus immature aphids–is present.”
Transform WG insecticide was recently approved for control of sugarcane aphid in sorghum under a Section 18 emergency exemption, according to Knutson.
AgriLife Extension district reporters compiled the following summaries:
Central: Grass growth was outstanding as a result of previous rains. Row crops benefited too. This past week, conditions were hot and dry. The drier weather meant a lot of the early grass growth was harvested as hay. Dryland forage sorghum was starting to suffer from dry conditions. First hay cutting reports were good. Dryland hay producers were waiting on another rain before applying fertilizer for a second cutting. In some areas, pa stures a nd other vegetation were beginning to show signs of moisture stress. Corn neared being ready for harvest. Stock-water tanks remained full, and creeks were flowing. Livestock continued to be in good condition where grazing was good. Some early nut drop was reported for pecans. Early blight was a problem in tomatoes. Horn fly numbers increased.
Coastal Bend: Hot dry conditions continued to dry out soils. However, the dry weather was conducive to harvesting hay and small grains. Some light rains in some areas slowed grain sorghum harvesting. Cotton needed more moisture, but decent yields were still thought possible.
East: The region was mostly hot and dry. Pastures and rangeland were in good to excellent condition. Topsoil and subsoil moisture remained mostly adequate in all counties except Wood, where both were reported as short. Creek and pond levels were good. Most producers had abundant grass, and hay harvesting continued with excellent quality and quantity reported. Armyworm and grasshopper infestations continued to be a problem. Henderson County corn was in excellent condition. Local farmers markets were doing great business, with fresh produce sales strong. Cattle were in good to excellent condition. Producers were weaning and selling market-ready calves and cull cows.
Far West: The region remained hot, windy and dry, with the exception of Presidio County, which received 0.25 to 0.75 inch of rain. Subsoil and topsoil moisture were adequate to very short. Pastures and rangeland remained in fair to very poor condition. Winter wheat was harvested. Cotton was squaring and in fair to poor condition. Corn was in poor to fair condition.
North: Topsoil moisture throughout the region was mainly short to very short with a few counties reporting adequate levels. Dry, hot summer conditions had arrived. There was very little to no rain throughout the region. Forage growth slowed, and soils were drying out. Crops were still faring well. Corn, grain sorghum and soybeans looked good. The oat and wheat harvests were completed. Hay producers in Collin County were still harvesting, with yields ranging from 2.5 to about three tons per acre. Livestock were in good condition. Grasshopper populations were increasing across the region. Feral hogs were still causing damage in Camp County.
Panhandle: The region remained hot and dry, with temperatures near average all week. Soil moisture was short to adequate. Cotton development in Collingsworth County varied widely, from replanted cotton struggling to catch up to older cotton that looked good. Deaf Smith County crops were doing well. Corn began to tassel, about 10 days behind normal. Grain sorghum was doing well with late plantings just maturing. Hansford County reported the wheat harvest was nearly completed. Some irrigated wheat yields were as much as 90 bushels per acre. Corn was in very good condition except some hail-damaged fields. Weeds continued to be a problem. Rangeland and pastures continued to improve. Cattle were in good condition.
Rolling Plains: Hot, sunshiny weather benefited cotton. Some producers turned irrigation pivots back on as conditions became dry. Cotton conditions varied widely from county to county and even within counties. Some fields were in excellent condition, while adjacent fields were very poor. The variations were attributed to time of planting. Pastures and rangeland were in excellent condition. Recent rains and sunny days made grass and forages seemingly shoot up overnight. Producers were baling grass and alfalfa hay. Cattle prices remained high, and producers were generally selling calves instead of keeping them. Some producers were looking for replacement females. Some farmers were already plowing wheat ground in preparation for fall planting.
South: Windy and hot weather continued. Some parts of the region received rain, which benefited rangeland, pastures and row crops. The showers also helped producers save irrigation costs. In the northern part of the region, all counties reported 40 to 100 percent adequate soil moisture. Hay producers were busy cutting and baling. Grain sorghum and corn producers were preparing to harvest. Watermelon harvesting was ongoing. Stock-tank water levels were dropping quickly in some areas due to high winds and heat. Supplemental feeding remained steady due to declining forage quality and quantity. Cattle body condition scores were beginning to decline. In the eastern part of the region, soil moisture was adequate due to rains. Row crops, including cotton, were progressing well. Harvesting of small grains began in some earlier planted fields. In the western part of the district, good rains were greening up rangeland and pa stures. Soil moisture throughout the area was surplus, except for very short soil moisture in Webb County. Farmers were preparing to or were already harvesting corn and sorghum. Vegetable harvesting was ongoing. Rains halted corn and sorghum harvesting in some areas, but it was welcomed by cotton growers. Pecans continued to make good progress, and the watermelon harvest was completed. Livestock were mostly in good condition. In the southern part of the district, light showers slowed corn and sorghum harvesting in some counties. Most cotton was setting bolls. Willacy County received 0.25 inch to 1.5 inches of rain, which kept soil moisture adequate. Soil moisture throughout the rest of the southern part of the region was short to very short.
South Plains: The region remained dry with sunny skies. Cochran County cotton was from seven-leaf stage to 15 true leaves with square setting very good. Weeds were a problem in cotton fields. Peanuts were blooming and pegging, and pod set was progressing. Thanks to earlier rains, all other crops were in good condition, including pastures and rangeland. Since May 23, Floyd Country had received between 13 to 15 inches of rain in some areas. Cotton was progressing well where rains had been good. Watering continued on cotton were irrigation was available. Rangeland and pastures were mostly in good to excellent condition. Livestock producers were able to quit supplemental feeding of cattle. Livestock were in good to excellent condition. Some producers were spraying to control mesquite. In Lubbock County, much of the cotton crop remained behind schedule due to late May rains and violent storms. Only a few fields had reached bloom s tage. Corn growth stages ranged from the vegetative to silking. Grain sorghum ranged from emergence to the late vegetative stage. Some early planted sunflower fields were in full bloom. Producers were working hard to get weeds under control. The Swisher County wheat harvest was nearly finished. Cattlemen were taking advantage of emergency grazing on U.S. Department of Agriculture conservation reserve program acres.
Southeast: Soil moisture throughout the region varied widely, with most counties reporting it as being adequate, but with others reporting from 100 percent very short to as much as 100 percent adequate. Rangeland and pasture ratings varied widely too, from excellent to poor, with good ratings being the most common. Recent rains in Brazoria County continued to help crops and pastures. With drier weather expected for the next week, many hay producers began cutting and baling hay. Livestock were in good condition. Crops in Chambers County were progressing and moving into boot and heading stages. The first rice crop in Chambers County was estimated to be three to four weeks away. After scattered to heavy rains in Orange County, forage growth was good and soil moisture adequate.
Southwest: In the western half of the district, hot, dry conditions were taking a toll on pastures. About one-third of the counties in that part of the region reported soil moisture as poor to very poor, and half short to very short. In the eastern half of the district, pastures and crops were beginning to suffer from lack of rain. However, corn was mostly past the dented stage and needed the dry weather. Grain sorghum was beginning to turn color. Cotton was, for the most part, late in squaring and setting bolls. Hay producers were reporting heavy yields across most of the eastern district.
West Central: Hot, dry, windy days with warm nights were adversely affecting soil moisture. Wildfire on rangeland was expected to soon become a concern. All wheat was harvested. Irrigated cotton planting was finished, and dryland cotton planting was underway. Producers were spraying already planted cotton for fleahoppers. Hay cutting and baling continued. Spring hay crops were growing but needed rain. Summer forages and grasses were showing signs of heat stress. Livestock remained in good condition. Stock-tank water levels were dropping. Pecan trees that made it through the drought still promised an excellent crop, but will need rain for nut fill in the next few months. Pecan growers were treating for insects.