Late-planted Arkansas cotton needs an ideal September for maximum yield during a season featuring pressure from stubborn pests including bollworms, plant bugs and pigweed, said Tom Barber, Extension cotton specialist with the University of Arkansas Division of Agriculture.

Thanks to an abundance of spring rains, “we have a late crop, one of the later ones in a while,” he said. “The late crop needs a good September in order to be a good crop.”

Optimal planting dates for Arkansas are between April 20 and May 20, but this year, “approximately 40 percent of our cotton was planted after the May 20 window,” Barber said.

A good September for the late crop would be a warm September, said Don Plunkett, Jefferson County extension staff chairman for the division. “And I think we’ll need a warm first half of October on many fields.”

Cotton growers are resorting to an old technology to defeat a newly evolved foe: herbicide resistant pigweed, also known by the more graceful name Palmer amaranth.

“Many fields contained this problem weed and had to be hoed or hand-pulled by chopping crews,” Barber said.

“Hand hoeing is more common and is most limited by the lack of available labor,” said Ken Smith, extension weed scientist for the division. “I suspect farmers will hand weed close to 100,000 acres in the state this year.”

Insect pests have also made the 2009 growing season tough for cotton farmers.

Arkansas growers are seeing heavy pressure from plant bugs, especially in later planted cotton. The tarnished plant bug has quickly risen to No .1 on the cotton insect pest list since the eradication of the boll weevil. These insects cause damage by feeding on squares, flowers, young bolls and tender plant tissue.

“Insects such as bollworms and plant bugs have been tough this year, especially plant bugs,” Plunkett said. “We have had some resurgence of populations within just days of applications of some insecticides.

“We are near the time of year when we would stop spraying for plant bugs, but farmers don’t want to stop too soon and let them attack small, tender bolls,” he said.

Arkansas is the nation’s No. 3 cotton state. In 2008, Arkansas growers harvested 615,000 acres for nearly 1,012 pounds of lint yield per acre compared with the 813-pound national average, according to the National Agricultural Statistics Service. NASS said on Monday that 9 percent of the crop had open bolls, slightly ahead of last year’s rate, but behind the 10 percent five-year average.