Jan. 22, 2004

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CANYON – Commercial growers of black-eyed peas must be vigilant against an array of insects which can significantly reduce crop quality rather than yield, according to a Texas Cooperative Extension integrated pest management (IPM) agent.

"On the High Plains there are three classes of insect pests we need to monitor when growing black-eyed peas," said Monty Vandiver, Extension IPM agent in Parmer County. "The hit list includes foliage feeders, pod feeders and root feeders. Of these, root feeders do the least amount of damage. They are low risk, so to speak."

Vandiver was one of 12 featured speakers at the second annual High Plains Vegetable Conference held Jan. 13 on the campus of West Texas A&M University in Canyon.

"There are no established damage thresholds for these insects, so you must monitor your fields carefully and stay on top of population numbers through field scouting," he said. "We also don't have many control chemicals to choose from, so it is very important that you know which remedies are available and how to use them properly according to label directions."

The most common foliage feeding insects that attack black-eyed peas are beet armyworms, loopers and grasshoppers. The list of pod-feeding insects includes podworms (known in other fields as cotton bollworms or corn earworms), lygus bugs and stinkbugs. Pod-feeding insects typically cause more damage by reducing bean quality rather than quantity.

"It is very hard to detect podworms by trying to count their eggs. Podworms feed on the blooms first, and then they bore into the pods. They feed on the immature peas in the pod, and the hole they bore in the pod is an entryway for moisture – which can stain and discolor the remaining peas," Vandiver said. "Larger pod-feeding insects such as lygus bugs and stink bugs are easier to see and detect, but their populations are generally large and getting larger by the time we can pick them up through field sampling."

Lygus bugs and stink bugs also are highly mobile. They cause damage by puncturing the pods to feed on immature peas, which reduces the overall grade of the crop.

"Fortunately, there are some insect predators in our fields that feed on these pests. Minute pirate bugs, ladybugs, lacewing larvae, damsel bugs and crab spiders are the insect predators we want to protect," Vandiver said. "All of these beneficial insects will feed on the eggs and larvae of our foliage and pod-feeding pests."

Plant disease is another threat for black-eyed peas.

"Early planting and frequent irrigation can cause seedling disease that can often be avoided by simply choosing a later planting date and allowing plants to dry fully between irrigation applications," Vandiver said. "Fusarium wilt is a disease that we see quite often in black-eyed peas. It causes the plants to yellow and can prove fatal.

"We can guard against fusarium wilt by selecting resistant varieties, and by using seed that is know to be disease-free."

Blight, leaf spot and mildew most often appear later in the growing season. In most cases, the crop will outgrow these lesser diseases if its fertility and water needs are met, the IPM agent said.

"One of the most important cultural practices we can use to control insects and disease is keeping our fields clean of weeds. Black-eyed peas are most susceptible to insect damage and fatal diseases when plants are young," Vandiver said. "It's a good idea to give them a leg-up by planting in weed-free soil.

"Young pea plants won't have to compete with weeds for soil nutrients in a weed-free field, and there also won't be host plants (weeds) available to harbor and support insect pests and diseases when the pea plants are most susceptible."

The High Plains Vegetable Conference is a collaborative effort of Texas Cooperative Extension, West Texas A&M University and agribusiness. Growers, shippers, packers, industry representatives, extension specialists and researchers from five states were among the attendees.