By Robert Burns
Agronomist gives ‘heads-up’ over armyworm concerns in headed-out sorghum
Texas A&M AgriLife Extension Service experts warn grain sorghum producers they should now be ever more vigilant in scouting for armyworms in the coming weeks as the crop heads out.
“The second-generation trap counts showed they were very high,” said Dr. Calvin Trostle, AgriLife Extension agronomist, Lubbock. “Compared to 2011, which was considered a bad year, they were even higher in July.”
Trostle noted that Dr. Pat Porter, AgriLife Extension entomologist at Lubbock, has continued to report large numbers of both armyworm moths and larvae throughout the region. But the situation requires even more vigilance in late August as sorghum heads mature.
“The worm damage in the whorl is mostly a cosmetic thing as long as they don’t go down into the head,” he said. “Now we have a lot of headed sorghum in the South Plains and West Texas.”
The whorl refers to a set of leaves growing from the stem of the plant in a circular pattern, Trostle explained. In sorghum, the seed head does not develop until the latter boot stage, then flowering.
“Once sorghum heads out, the worms are going to go there and feed on the head, and that’s where the real economic damage occurs,” he said. “Normally, we recommend scouting once a week, but with the counts so high, I’d suggest farmers scout more often, perhaps every five days.”
Though much dryland grain sorghum in the High Plains is currently drought-stressed, there’s still the potential for some very good yields, Trostle noted. Another rain in the next week or two would really make a difference.
This is because grain sorghum is considerably more drought-tolerant than comparable crops such as corn, he said. One of the moisture-critical stages of corn or sorghum is during the flower/pollination period.
“For a corn crop, that is uniform across the field, you may have about three days for conditions to be right for good pollination,” Trostle explained. “With grain sorghum, you’re going to have a wider window, because it will start to flower at the tip of the head. A small sorghum head, say a 5-inch head, may take five days to flower from top to bottom. If it’s a large sorghum head, like 9 inches, it may take seven days to flower from top to bottom. That’s one of the things that insulates sorghum a little bit from the worst, dreadfully hot days when you have flowering going on. Because, even if it is hot enough to bite the head a little bit, they’re not going to be completely struck down.”
AgriLife Extension district reporters compiled the following summaries:
Central: Crops under irrigation looked good. In some areas, pastures were showing signs of moisture stress as triple-digit temperatures and dry conditions continued. However, many areas were still in great shape. The corn harvest neared completion, however there were issues of grain storage shortages. This has slowed some harvesting, as have sugarcane aphid issues. Tanks and creeks were full, and forages were plentiful, which kept livestock in good condition. Hay harvesting stopped, and pecans were beginning to drop. If hay meadows would receive another rain, they could produce one final cutting.
Coastal Bend: Early yield reports for both soybeans and cotton were above average. Some cotton fields produced 3.5 bales per acre, and soybeans produced more than 50 bushels per acre. Rice yields were about average, with some fields producing more than 8,500 pounds per acre. Hay making continued at a steady pace. Burn bans were enacted in some counties due to very dry conditions and high winds. Rangeland conditions declined after a week of near 100-degree temperatures and no rain. Cattle prices remained high, but inventories low. Water levels of creeks and ponds were rapidly dropping.
East: Most of the region was hot and dry, with only Henderson and Jasper counties receiving spotty showers. Harrison and Polk counties reported subsoil moisture as short, while all other counties reported it as mostly adequate. Forage growth slowed, with quality dropping as grasses matured. Trinity County reported the early rains caused an abundance of pasture grass. Armyworm infestations decreased, but grasshoppers continued to be a problem. Fruit and vegetable production slowed. Corn was being harvested, with outstanding yields predicted. Lake and pond levels were good. Cattle remained in good condition. Some producers in Anderson County began to supplement cattle with protein. Feral hogs were active.
Far West: Hot and muggy weather continued, with some scattered showers. The western side of Ward County got 1 inch of rain. Subsoil and topsoil moisture was short to very short, with the exception of Reagan and Hudspeth counties, which reported adequate to short. All corn was in good to excellent condition. Cotton was in fair to good condition, with all of the crop setting bolls and much of it squaring. Part of the Upton County grain sorghum crop was coloring and heading. Pasture and rangeland remained in poor to very poor condition.
North: Most of the region reported short to adequate topsoil moisture. From 0.2 to 0.5 inch of rain fell across the region. However, the region generally remained hot and dry, with highs in the upper 90s to 100s. The corn and sorghum harvests were ongoing, with average to slightly above average yields reported. Growth of summer pastures slowed because of dry weather. Hay fields were wilting from the heat, but harvesting still continued in a few counties. Overall, cattle were in good condition. Armyworms and grasshoppers continued to be a problem. Sugarcane aphids attacked sorghum-Sudan hay. Feral hogs were still a threat.
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