Plant bugs and thrips continue to make their presence known in cotton across North Carolina.
Thrips have been a longtime nemesis to Carolina cotton, but plant bugs are a fairly new pest in the state and have become more prevalent the past few years. Dr. Dominic Reisig, North Carolina State University Extension entomologist, notes that plant bugs have expanded in the state and last year expanded to new areas. Because of thrips and plant bug pressure, Reisig is urging scouting.
“If you’re not checking for plant bugs on your farm, I suggest that you do so,” the entomologist said at an Extension cotton meeting in Wilson Jan. 30.
“IPM (Integrated Pest Management) is critical, and the way that we do IPM in all of our crops relies heavily on scouting and identification,” Reisig said. “I cannot overemphasize the value of a scout or a consultant. We have phenomenal independent scouts and consultants in the state; we have phenomenal scouts and consultants who work for dealerships. These people help us make good decisions because in order to use the economic threshold, we have to know what inset is out there so that we can use the right insecticide.”
For farmers who have heavy thrips pressure, Reisig is recommending the use of insecticides as well as a seed treatment.
“My goal is not to get you to spend money. My goal is to get you to spend money if you need it. I think in certain situations we need to up the ante in terms of thrips control. We can’t just rely on seed treatments alone. We have seen resistance to a lot of neonicotinoid class of seed treatments from tobacco thrips,” Reisig said.
It is because of the resistance pressure that many farmers will need to use additional chemicals to control thrips. Reisig said farmers will need to determine if a seed treatment alone is enough or if they need to add insecticides.
Reisig pointed to work by Dr. Anders Huseth, a field entomologist at N.C. State, that shows that resistance to neonicotinoids is increasing in part because farmers are using many of the same chemicals in both soybeans and cotton.
“Where we have a lot of soybean acres we tend to see more resistance. Where we have a lot of cotton acres we see more resistance and where those two overlap we see a lot of resistance. Where there is cotton and not a lot of soy there is less resistance,” Reisig explained.
For thrips control, the evidence is excellent that earliest sprays work best. “I feel that you cannot be too early with a spray of Orthene or Radiant,” Reisig said.
For plant bug control in North Carolina, N.C. State has adopted best management practices from the Mid-South where plant bugs have been a longtime problem.
Reisig encourages farmers to plant their cotton away from corn, which is a source for plant bugs, but he acknowledges that can be a challenge due to rotation schedules. “If you have cotton near corn, recognize this is going to be a good source for plant bugs,” he cautioned.
Choosing early varieties and managing the correct fertility are also important for plant bugs. Tall or rank cotton is also a source for plant bugs. “Pay attention to the hairiness of your variety. Plant bugs love smooth leaf and semi-smooth leaf varieties,” Reisig said.