Those factors that allow the cotton crop to emerge rapidly and begin growing vigorously, such as warmer soil temperatures and adequate moisture, are the same factors that allow the plants to grow quickly through the primary thrips damage window. Earlier planted cotton is more likely to encounter thrips problems because of the longer time it takes for the seedlings to get past the critical stage.
Ron Smith, Auburn University Extension entomologist, says the two most significant factors affecting thrips damage appear to be planting date and rainfall.
"Growers planting behind the rainfall that occurred between May 7 and May 11 will likely not have to be concerned about making a foliar spray for thrips at the first true-leaf stage," he says. "Seed treatments alone should provide adequate thrips control."
Smith says thrips trials planted on April 16 in Prattville, Ala., showed low-to-moderate thrips injury with only seed treatments at planting.
"Trials planted a week earlier are showing heavy thrips injury behind all seed treatments," he says.
In North Carolina, Jack Bacheler, North Carolina State University Extension entomologist, says producers in his state should expect greater potential thrips problems in cotton planted before approximately May 10 than in cotton planted after that time.
"Slower seedling growth with earlier plantings typically accounts for most of this damage," he says.
In replicated tests conducted in thrips-prone areas of North Carolina, cotton that is planted after approximately May 15 often does well without a foliar application following a seed treatment.
Bacheler says this is because of quicker seedling grow-off and declining migrating adult populations.
Phillip Roberts, University of Georgia Extension entomologist, says at-planting systemic insecticides provide consistent yield responses and are used for early season thrips control.
"Supplemental foliar sprays may be needed if environmental conditions are not conducive for uptake of at-planting systemic insecticides or if heavy thrips infestations occur," he says.
Remember, scouting fields for thrips pressure is the only way to determine if the pressure is heavy enough to need a foliar spray.
Contact Amanda Huber at (352) 486-7006 or firstname.lastname@example.org.