U.S. cotton insect losses in 2008 were up slightly from 2007, according to a preliminary Beltwide survey of insect losses compiled by Mike Williams, Extension entomologist at Mississippi State University. The report was presented at the 2009 Beltwide Cotton Conferences in San Antonio.
Williams said cotton insect losses in 2008 totaled 3.79 percent of total yield. Average control costs per acre were $56.13, while costs plus loss averaged $76.11 across the Belt.
Williams said that in the 15 years of reported losses, losses ranged above 5 percent until 2000. “Since 2000, losses have not reached that 5 percent level and have dropped to a fairly low level. When we look back, the boll weevil eradication and the transgenic (Bt) cottons were in use or in action since 2000.”
Up until 2000, cost of management was continuing to rise each year, but have since been heading lower.
The new No. 1 damaging cotton pest in the United States is — drum roll, please — Lygus, or plant bug, with losses of 1.08 percent. It infested about 61 percent of cotton acreage. States with the highest percentage of losses include Arizona, California, Louisiana and Missouri.
Losses to heliothines (including cotton bollworm and tobacco budworm) dropped below 1 percent in 2008, according to the report. However, 3.8 percent losses were reported in Alabama. Two states, Kansas and Oklahoma, showed no losses at all to heliothine infestations.
Bt cotton acreage decreased for the second straight year in 2008, although this is more reflective of an overall decline in cotton acreage. Around 90 percent of U.S. cotton acreage had some type of transgenic technology, according to the report. The cost of Bt cotton exceeded the cost of foliar application this year, “and I believe that is the first year I’ve seen that happen,” Williams said.
Stink bugs were the No. 3 cotton pest this year with losses of 0.712 percent. The pest infests about 42 percent of total cotton acreage.
Thrips, the fourth most damaging pest, “have always been a tremendous problem in many states and always infest more acres than any other pest,” Williams said. “This year, we had thrips on 85 percent of our cotton acreage, and they caused about 0.57 percent losses. One of the things I found interesting was that the more northern states in the Belt had higher thrips losses than other states.”
Fleahoppers were the fifth most damaging pest in the United States, the report said. “They traditionally infest Kansas, Oklahoma and Texas. This year, they reduced yields by 0.47 percent and infested 2.2 million acres. There are probably light infestations of fleahoppers across the Belt, but normally, they don’t cause us a lot of problems,” Williams said.
Aphids were ranked sixth with yield losses of about 0.2 percent. Aphids infested about 63 percent of the 2008 crop.
Spider mites, ranked seventh, “have been of great interest to growers and consultants and are probably on the rise a little bit,” Williams said. “Tennessee recorded the highest percent loss to mites. All of the other states except New Mexico, Kansas and Oklahoma, reported infestations. The pest infested about 33 percent of total U.S. cotton acreage.
Rounding out the top 10 in losses were clouded plant bug, silverleaf whitefly and fall armyworm.
Twenty-three arthropod pests were reported as causing losses in 2008, according to the report, including two new ones — green mired, which infested Texas cotton, and the pale-sided fleabeetle, a pest of Arizona cotton.
In the “other pests of cotton” category was the once-feared boll weevil, which infested 224,428 acres in three states (Texas, Louisiana and Arkansas) in 2008, with Texas recording the highest losses. “Boll weevils are really no longer a factor in yield loss, but are still costing us money when we consider eradication costs,” Williams said.
Eleven other pests combined to cause less than 0.01 percent damage and infested a small percentage of U.S. cotton acreage.
By state, Alabama led the Cotton Belt in percent reduction in yield due to arthropods, with 8 percent, followed by Louisiana, 6.5 percent, Tennessee, 6.2 percent, Arizona, 5.6 percent, South Carolina, 5 percent, Arkansas, 4.95 percent, Kansas, 4.9 percent, North Carolina, 3.95 percent, Oklahoma, 3.2 percent, California, 2.87 percent, Mississippi, 2.34 percent, Florida, 2.26 percent, Georgia, 2.25 percent, Texas, 2 percent, Virginia, 2 percent, New Mexico, 1.06 percent and Missouri, 0.46 percent.
In 2007, the top five most damaging pests were bollworm/budworm, Lygus, thrips, fleahoppers and aphids.
Data for the report were collected by coordinators in each cotton producing state. The Cotton Foundation supports the project.