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Cole Crops [North]
Courtesy of Alton N. Sparks, Jr., University of Georgia,
www.InsectImages.org.
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Diamondback Moths
The diamondback moth larva is pale yellowish-green to green, and is covered with fine, scattered, erect hairs. Larvae also have a forked posterior. Larvae mature to be cigar-shaped and about 1/2 inch long. After hatching from the egg, larvae burrow into leaf tissue for about a week before exiting to feed externally on the plant. Disturbing the larvae will cause them to actively wriggle or drop from the leaf on a silken thread, which is a distinguishing characteristic.
Pupae develop after four instars into a delicate, loosely spun cocoon. After emergence, adults are about 1/3 inch long. They are slender, grayish-brown moths with folded wings flaring outward and upward at their back end. Males have a row of three diamond-shaped yellow spots along the middle of their back when they fold their forewings.
Recommendations
SpinTor® 2SC Naturalyte® insect control, with the active ingredient spinosad will control diamondback moth and manage insecticide resistance when used in a rotational program with a product containing the active ingredient Bacillus thuringiensis, endosulfan, permethrin or thiodicarb. |
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Courtesy of Alton N. Sparks, Jr., University of Georgia,
www.InsectImages.org.
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Courtesy of Clemson University —
USDA Cooperative Extension
Slide Series,
www.InsectImages.org.
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Armyworms (There are many species of armyworm. The following is a description that depicts some armyworm species.)
Armyworm larvae can grow up to 11⁄4 inches long. They have three lightly colored stripes running the length of their body. Black spots accompany the stripes on the second segment located behind the head.
Larvae pupate at fifth instar and the pupae are about 1⁄2 to 3⁄4 inch long. They are light brown with dark brown margins along their abdominal segments.
Forewings of adult armyworms are mottled gray or brown with a pale spot near the center of each wing. Their wingspan is 1⁄2 to 1 inch long and the hind wings are white with darker veins and a fringelike border.
The armyworm infects many weeds, trees, grasses, legumes, truck crops and field crops and is attracted to wild hosts such as plantain, lambsquarters and redroot pigweed.
Recommendations
Intrepid® 2F insecticide, with the active ingredient methoxyfenozide, and SpinTor are ideal rotational partners with products that contain the active ingredient methomyl in a foliar treatment program for this pest. |
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Courtesy of Alton N. Sparks, Jr., University of Georgia,
www.InsectImages.org.
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Cabbage Loopers
Cabbage looper larvae are green caterpillars with white stripes running the length of their body. Larvae can grow up to 1 1/4 inches long, and the body tapers toward the head. There are three pair of legs near the head, and three pair of fleshly prolegs near the posterior. The body is humped or “looped” when moving or resting.
After five instars, larvae pupate into a fragile, silken cocoon. Young pupae are a light greenish color that gradually turns dark brown when mature. They grow to 3/4 inch long.
Adult cabbage loopers are mottled, grayish-brown and have a wingspan of 1/2 inch, with a small silvery-white figure eight in the middle area of each of the front wings. Forewings have two shades of grey and blackish zig-zag stripes with hind wings being a pale brown in color. Another characteristic is a tuft of hair arising from behind the back of the moth’s head.
Recommendations
Intrepid and SpinTor may be rotated in foliar treatments for control of cabbage loopers. Products with the active ingredient acephate thiodicarb or zeta-cypermethrin can also be used in a resistance management program. Up to three generations can be seen per year. |
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Courtesy of Joseph Berger,
www.InsectImages.org.
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Courtesy of Clemson University — USDA Cooperative Extension Slide Series,
www.InsectImages.org.
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Imported Cabbageworms
Imported cabbageworm larvae have a yellow strip down their back and a row of faint yellow spots on each side of a velvet-like green body. Fully grown, larvae can be 1 1/4 inches long and can be detected from the wet, greenish-brown excrement left on leaves. After feeding, larvae leave holes in leaves and more commonly eat through veins. Another difference from cabbage loopers is that imported cabbageworm will bore into the center of a cabbage head.
Pupae are bare structures that are sharply-angled and attached to the lower leaf surface by a silken loop. A pointed protrusion accompanies the distal end of the 3⁄4 inch long greenish colored structure that eventually turns brown.
Adults are white butterflies with a black area near the tip of each forewing, and each hind wing has a small black spot on the front edge. The undersides of the wings, which can be about 2 inches long, are tinged with yellow. Black spots are also on the top of the forewing with males having one spot, and females two.
Recommendations
With three to four generations each year, Intrepid and SpinTor can help control this pest. The active ingredient Bacillus thringiensis, chlorpyrifos, endosulfan or methomyl can be found in products that can be incorporated into a resistance management program. |
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Courtesy of Whitney Cranshaw,
Colorado State University,
www.InsectImages.org.
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Courtesy of Whitney Cranshaw,
Colorado State University,
www.InsectImages.org.
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Leafminers
Coiled mines in leaves, with one end slightly enlarged, indicate leafminer infestation. The maggot is colorless to bright yellow, and up to 1/8 inch long.
Pupae are flattened, segmented and oblong-oval in shape. At slightly less than 1/8 inch long, young pupae are bright yellow, but gradually turn brown.
Adults are slender at about 1/8 inch long.
Recommendations
SpinTor® 2SC Naturalyte® insect control, with the active ingredient spinosad, applied as a foliar treatment can be rotated in a resistance management program with products containing the active ingredient cyromazine or permethrin. |
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Courtesy of Jack T. Reed,
Mississippi State University,
www.InsectImages.org.
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Thrips
Adult female thrips are about 1/16 inch long, yellowish-brown to dark brown in color, and have wings. Adult males are light yellow and smaller than the females.
Larvae go through two instars, but are translucent-white and have red eyes during both stages. During the first stage, larvae are tiny and almost worm-like. Larvae in the second stage are similar to the adult in size and shape. Pupae are yellowish in color with antennae and wing pads.
Puckered, twisted leaves and pale spots on the leaf surface are physical indications of thrips. This insect feeds on almost any flowering plant.
Recommendations
Use SpinTor in a rotational program with products containing the active ingredient cyfluthrin or methomyl. |
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For a complete IRM cole crops management guide, visit the Commercial Vegetable Production in Wisconsin Guide or the Ohio Vegetable Production Guide.
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