The Mid-South has been ground zero for tarnished plant bugs for many years while the pests have become a relatively new threat for farmers in the Southeast. In Louisiana, crop consultant Hank Jones has been helping farmers battle plant bug pests for 20 years and is considered one of the “go to” guys for controlling plant bugs in cotton.
In North Carolina, cotton farmers are developing action plans to control plant bugs that were first discovered in the northeast part of the state and are now expanding to other cotton growing regions as well.
In the Mid-South, farmers use an integrated pest management approach to managing plant bugs; North Carolina State University Extension Entomologist Dominic Reisig believes an integrated pest management approach will work best for North Carolina cotton farmers as well.
Louisiana consultant Jones, based near Winnsboro in northeastern Louisiana cotton country, uses an integrated pest management approach for his cotton farmer clients. Reisig says North Carolina farmers can learn much from the expertise and experience of Jones which is why he was invited to speak at Certified Crop Advisor (CCA) training at the Johnston County Ag Center in Smithfield on the morning of Dec. 9.
On the afternoon of Dec. 8, Reisig and Jones traveled north to speak at the fall conference of the North Carolina Agricultural Consultant’s Association in Raleigh. Jones told the consultants that job one in managing tarnished plant bugs in cotton is to know where the pest is coming from.
"They are are not going to originate in a cotton field. They’re coming from somewhere else. How are we going to manage plant bugs? By figuring out the landscape around yourself. It’s a great migration. When you see brown silks in corn, and it’s next to a cotton field, you’re fixing to have an influx of plant bugs into your cotton. The amount of injury may depend on what stage your cotton is at the time. But injury levels increase rapidly during this migration,” Jones said.
Jones noted that most of the plant bugs in cotton in Louisiana migrate from corn planted next to cotton. He said determining where your cotton is relative to corn is the first step in developing your scouting plan for plant bugs.
“When cotton gets to five-leaf or pinhead square, it’s time to start scouting for plant bugs. Adults migrate rapidly. Scout your field borders. If you can grasp where in the system your plant bugs are coming from, it at least gives you a management tool to throw into your back pocket,” Jones said.
“Post-bloom, I am more concerned about nymphs than I am adults. Nymphs don’t go anywhere; they don’t’ have wings. Nymphs are harder to scout due to their small size and lack of movement. They are lower in the canopy; they are going to go down into the canopy of the plant to escape exposure to heat and insecticide residues,” he said.
In essence, Jones said successful IPM in cotton in the Mid-South requires you to “spray, spray, spray, spray and spray.” In infested fields, Louisiana cotton farmers often have to spray for plant bugs up to eight or nine times.
“Maybe I can get down to six sprays. How do I do that? You have to know your landscape, know the acceptable levels of injury. Manage cotton for earliness. Kill those pigweeds and marestail. You might use border sprays in the right situations and that might keep a big influx of continuing populations in check before they disperse into the entire field,” he said.
Rotating chemistries and using the correct rates is vital.
“Give yourself as many heads up as you can, to give you the advantage to at least know how to time things better where you don’t get behind. If you get behind, you’re behind all year, and you will have to spray yourself out of some horrible situations,” Jones said.
And indeed, insecticides do lose their efficacy by the eighth or ninth spray. “Once you get into August, acephate is going to kill 40% to 50% of your plant bugs, maybe. Your tank-mix is going to decline in efficacy. Transform (insecticide) is not going to work as good in August as it does in June,” Jones said.
For plant bug control in North Carolina cotton, Reisig believes a two-part threshold based on time of the growing season (pre and post-bloom) will work best.
He said scouting is critical and he strongly advised farmers to hire a professional consultant to scout their cotton for plant bugs. He noted that in effective scouting you will need to check your fields for plant bugs at least once a week. Depending on the field and growing conditions, you might even have to scout twice a week.
“You may need six sprays if your cotton is next to corn or if you plant your cotton later. If you plant earlier in hot-spot areas, maybe three sprays,” Reisig said.
Reisig said the best management practices for plant bugs in the Mid-South will have to be adjusted for the Southeast. For example, he noted that Transform applied at a rate of an ounce and a half per acre works in the Mid-South, but in the Southeast a dose of at least two ounces is needed for maximum control.
“One thing we have done is we tested some of those populations for what we thought might have been Transform resistance. We don’t see any difference in terms of baseline response of the insecticide. I can’t explain why that is. Despite that, my recommendation is two ounces and above, based on our replicated research trial results” Reisig said.