Combatting Curculio in Black-eyed Pea Crops
Black-eyed peas have long been a symbol of New Year’s luck in the South, but black-eyed pea farmers aren’t feeling that fortunate.
The legume has been part of a boom-and-bust cycle for the past three decades thanks to a pod-feeding weevil, the cowpea curculio, that has evaded farmers’ best pest control practices. This year is going to be a bust due to high pest pressure, said David Riley, a University of Georgia College of Agricultural and Environmental Sciences professor of entomology.
“The crop is really under severe pest pressure,” Riley said. “Some years the crop is good, but the reason this has reached a critical point this year is because the last few available insecticides that we were using to control this pest have stopped working.”
The pest pressure was so bad last year that the largest pea grower in Georgia’s largest pea-growing county, Colquitt County, sold his pea-shelling equipment at the end of the season, said Jenna Brock, a UGA Cooperative Extension agent in Colquitt County.
“They were our main pea grower, with hundreds of acres, and he’s just gotten out of it,” Brock said. “He still grows other vegetables — spinach and some corn — but peas that were packaged and sold frozen in the grocery store have been a big part of his business.”
Colquitt County went from growing almost 1,800 acres of Southern peas in 2015 to less than 500 acres in 2016, Brock said.
“If we can’t solve this problem, Southern peas will never come back to Georgia in a big way,” Riley said.
A rich history
At the turn of the 20th century, Southern peas — the family of legumes including black-eyed peas, purple-hulled peas and crowder peas — covered close to 6 million acres of the Southeast. They were the primary legume grown during that period and used for livestock feed until World War II, when the soybean took over.
What was left in the Southeast was the close to 30,000 acres of cowpeas that make their way to our local supermarkets each year.
Southern peas started facing pressure from the cowpea curculio in Georgia in 1873, and by the 1910s, the pest was widespread throughout the South. By the 1980s, pyrethroid insecticides were the most effective control, but even that group of insecticides can’t control the pest. Populations of the cowpea curculio overwinter readily, and after a few years of building up populations, become unmanageable. When farmers stop planting Southern peas for a few years, the curculio population can drop if no peas are grown in the region. Then farmers start growing Southern peas again, and the cycle reboots.
Riley took his post as a vegetable entomologist with UGA in 1996, and in 1997, the large black-eyed pea marketers pulled out of Georgia because of curculio problems. Georgia black-eyed peas were just too riddled with damage to meet consumer demand. The acreage of black-eyed peas in Georgia plummeted, and with it, so did cowpea curculio populations.
With fewer curculio problems, acreage began to rebound, peaking in 2015 at about 7,600 acres, according to UGA’s Center for Agribusiness and Economic Development.
Then, as the acreage peaked, so did curculio problems, Riley said.
UGA vegetable horticulturists and entomologists have robust pest-control research programs for most of Georgia’s larger vegetable crops. But those integrated pest management programs have been developed through years of research, and that research costs money, money that often isn’t abundant for small-acreage crops like black-eyed peas.
Solutions to the problem
Research at UGA is focused on ways to reduce the impact of the overwintering curculio population in the Southeast.
Riley believes that the solution to the pea problem will involve developing a trap crop that can be planted in the spring to trick the curculios into laying their eggs early and in the wrong crop. There are also efforts underway to breed weevil-resistant Southern peas.
Hitting on resistance would have a larger impact not only on south Georgia pea farmers, but on families around the world who rely on Southern pea varieties as dietary staples. Across Africa, farmers grow about 26 million acres of Southern pea varieties.
“If you don’t have the curculio, it becomes one of the easiest, cheapest crops to grow,” Riley said. “It naturally fixes its own nitrogen in the soil, and most of the disease and other insect problems are easily manageable. They’re the most drought-tolerant legume you can grow.
“It’s got all of the pluses and this one, big minus. If we would just take care of this curculio, we could have large acreage again because it is truly a very utilitarian crop.”
By Merritt Melancon