Cotton growers need to continue to monitor for whiteflies, as the pest is starting to impact fields across the Southeast, according to Alabama Extension cotton entomologist Ron Smith.
“I know we’re finding them as far north as Quitman County (Georgia), which is just across from Eufala, Alabama. We know we’ve got them in the Panhandle of Florida, and we know we’ve got them in some fields in the corner of Alabama down in the extreme tip between Georgia and Florida,” Smith said. “(Growers) are going to have to keep a watch on them. You don’t want to spend any money you don’t have to spend. But then again, on the other hand, you can’t be too late. You’ve got to find that happy medium.”
According to University of Georgia Extension cotton entomologist Phillip Roberts, silverleaf whitefly populations exploded in Georgia fields in early July.
Impact on Late-Planted Cotton
Smith stated on July 31 that the biggest concern with the current whitefly outbreak is with late-planted cotton, or the crop that was planted in late May to June 20.
“If we can get into August without having any, the worst-case situation with our older cotton would be a one-shot spray. The concern is we’ve got a lot of late-planted cotton down here. That cotton needs to try to make on into September. That’s where our greatest risk is,” Smith said. “That cotton has got to make in August and September, not July and August.”
Whiteflies have more time to show up and infest cotton if it matures later.
“One way to avoid insect problems, particularly if they come late in the season, is to try to avoid it by having your cotton as mature as possible before they get there,” Smith said.
Difficult to Control
Whiteflies are difficult to control because of their prolific reproductive cycle. A female can lay between 150 and 200 eggs, and it only takes those whiteflies two to four weeks to mature into the adult stage and begin reproducing.
Scouting remains the best course of action against whiteflies, which are sucking insects that feed on the underside of leaves and excrete a sugary substance called “honeydew.” This serves as a host for sooty mold fungus. The accumulation of honeydew and sooty mold leads to quality problems on open cotton bolls. When uncontrolled, whiteflies can reduce cotton yields and affect cotton quality.