Canyon, Texas
January 22, 2004
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.
Writer: Tim W. McAlavy (806) 746-4051,
t-mcalavy@tamu.edu
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