Plant bugs dominate cotton fields, weather forces management tweaks

BY Alabama Cooperative Extension System
Posted 7/19/23

AUBURN UNIVERSITY — The 2023 Alabama cotton crop had a late and slow start. Spring rains and cool temperatures caused planting delays, then slowed emergence and seedling growth.

Summer was …

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Plant bugs dominate cotton fields, weather forces management tweaks


AUBURN UNIVERSITY — The 2023 Alabama cotton crop had a late and slow start. Spring rains and cool temperatures caused planting delays, then slowed emergence and seedling growth.

Summer was a tale of two Junes. Early June brought extended dry weather. However, abundant — sometimes excessive — rainfall in late June made crop management more difficult. These prolonged heavy-rain events prevented weed, insect and disease control applications, which hindered the cotton crop in its early stages. To add more to the mix, the end of June brought high temperatures and humidity, creating additional challenges. These combined conditions have forced cotton producers to adjust their management plans.


Alabama Cooperative Extension System Cotton Agronomist Steve Brown said he spoke to growers with blooms on June 22. Conversely, during the last week of June, he saw cotton in the cotyledon stage.

"We've got cotton in a wide range of growth patterns," Brown said. "In last the two weeks, most areas have caught up on rainfall. However, we've entered a hot, dry pattern and cotton is going to need another rain soon."

Brown said while the Alabama cotton crop is late, there is no need for panic. If the late pattern holds, producers will need to think about being more conservative with nitrogen, more vigilant with insect control and more aggressive with plant growth regulators (PGRs).


Alabama Extension Cotton Entomologist Scott Graham said producers are in the height of the worst widespread plant bug situation that Extension professionals can recall in the past 51 years. Graham and his counterpart, Ron Smith — also a cotton entomologist — encouraged producers to plan for adult plant bug control during the 2023 season.

Brown and Graham were hoping to count blooms on cotton plants at a trial on the Prattville Research Unit. Instead of counting blooms, they found that though the crop was 57 days old, first bloom was approximately a week away. There was also evidence of plant bug feeding and loss of pinhead squares. Brown normally expects to see flowers in cotton between 50 and 60 days after planting. Brown said the Prattville site demonstrated what many farmers are facing — a crop delay.

"We've seen plant bug situations like this in pockets before, but farmers from Mississippi, Alabama and Tennessee, all the way down to the Gulf, are all fighting migrating plant bugs," Graham said. "Some fields have already been sprayed three times, which is uncommon at this point in the season."

Graham said the heavy plant-bug pressure could be weather related, because the primary host plant early in the season — daisy fleabane — was prolific and didn't dry down at one time.

"Because it didn't dry down like we anticipated, we are seeing multiple flights of plant bugs moving in," Graham said. "Normally, we have one flight of adults and manage those, then two weeks later we begin fighting the immatures. Right now, producers are seeing flights of adults week after week."

One of the most difficult things about controlling plant bugs is that no products provide complete or residual control. One spray application manages what is in the field and provides control for two to three days. Any flights of adult plant bugs after that period are flying into a field with no control measures in place.

"Some producers had plant bugs but couldn't get into the field to make an application," Graham said. "We don't usually anticipate seeing immature plant bugs until the first week of bloom. However, I was in a field in late June that didn't have blooms but had third instar nymphs. Those plant bugs have been there for a long time."

He said those fields require different management, as early plant bug flights alter insecticide recommendations.

"In some areas, pyrethroids are out for plant bugs, which leaves the organophosphates to control stink bugs and plant bugs later in the season," Graham said. "That could potentially be a problem, but this is why we build in a rotation to deter resistance."


Graham said the threshold for plant bugs is eight bugs per 100 sweeps.

"That is roughly 1,160 plant bugs per acre," Graham said. "Literature says they can feed on anywhere from .6 to 2.1 squares per day. If you leave a threshold population of adult plant bugs in the field for seven days, they will eat roughly 25% of the squares in the field."

The threshold is to maintain 20%. By not doing anything, producers would fall below square retention threshold.

"More importantly, though, adult plant bugs lay approximately 100 eggs during their life," Graham said. "This means producers would have roughly 58,000 eggs deposited in the field, which will hatch out over a seven- to 10-day period."


Graham has been studying ThryvOn technologies for nearly 10 years. However, this is the first growing season where it has been available to every producer.

"This new variety boasted a strong resistance to thrips, and Alabama farmers were able to put it to the test with heavy thrips pressure," Graham said. "While it is not resistant to plant bugs, immature plant bug populations tend to be much lower and develop slower in ThryvOn cotton."

Graham said producers will still have to spray, but the timing on ThryvOn technology could be different than the spray timing on other varieties. The consumption of plant tissue slows the insect's growth, and, in turn, they cause less damage and lay fewer eggs.


Brown said cotton prices were between 80 and 83 cents per pound in early 2023. However, recent December futures are approximately 77 cents—well below what most farmers hope to see.

"Prices are dependent on weather, and it would probably take a significant weather scare to move prices back to the mid-80s or higher," Brown said. "There has been downward pressure on prices, but weather is a major factor, and there is a long way to go until harvest."