Major Insect Pests of Apple in Georgia
Codling Moth (Laspeyresia pomonella)
Larvae are pinkish-white caterpillars with brown heads, about 3/4 inch (18 mm) long. Larvae eat holes in fruit, burrow to the core, and frequently damage the seeds.
Plum Curculio (Conotrachelus nenuphar)
Adults are small, dark-brown snout beetles, about 3/8 inch long (9 mm) with mottled gray or brown markings. Larvae are yellowish-white, legless, brown-headed grubs, up to 3/8 inch (9 mm) long. Adults damage fruit by making small circular feeding punctures or small crescent-shaped cuts following egg laying. Early-season adult damage causes scarred, malformed fruit. Larvae tunnel and feed in developing fruit, often causing infested apples to drop.
Scale Insects
San Jose Scale (Quadraspidiotus perniciosus), Forbes Scale (Q. forbesi), and other scale insects can adversely affect apple.
San Jose scales are delicate, saclike, yellow insects, each covered by a grayish, rounded, or somewhat oval armor about 1/16 inch (1.5 mm) across. The armor covering bears a nipple-like projection near the center (females) or near one end of the more elongated forms (males). Heavy infestations often give limbs a gray, encrusted appearance. Wood under infested bark often has reddish-purple spots or streaks where tissue has been killed. Infested trees exhibit a loss of vigor, terminal die-back, and eventually die if the scale is not controlled.
The Forbes Scale resembles the San Jose Scale in appearance and damage.
Redbanded Leafroller (Argyrotaenia velutinana)
These are slender, pale-green caterpillars with yellowish heads, about 3/4 inch (18 mm) long and feed on leaves and fruit. Leaves are skeletonized, folded and webbed together. Fruits are shallowly scarred, especially where they are in contact with infested leaves.
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Woolly Apple Aphid (Eriosoma lanigerum) and other aphids
Aphids that may infest apple include Rosy Apple Aphid (Dysaphis plantagines), Apple Aphid (Aphis pomi), and Apple Grain Aphid (Rhopalosiphum fitchii).
Aphids are small, about 1/12 inch long (2 mm), soft-bodied insects with two "tail pipes"' or cornicles projecting from the rear. The rosy apple aphid is purplish or rosy brown to brownish green with a long antennae. Apple aphids are green, black legged, with short antennae and cornicles. The apple grain aphid is light green with green legs and dark green bands on the abdomen. When high populations are present, especially of the rosy apple aphid, aphid feeding causes leaves to curl and stunting of the stems. They may also cause some distortion of fruit and a reduction in fruit size. The apple grain aphid is the least damaging.
Woolly apple aphids are small, about 1/12 inch (2 mm) long, purplish soft-bodied insects, normally covered by white, cottony masses. They may be found clustered near wounds on trunk, branches and roots. Root infesting forms cause the most serious damage. Infested roots often have numerous gall-like knots hearing the woolly masses of aphids. Fibrous roots can be completely destroyed, causing stunting of trees and sometimes tree death.
Tarnished Plant Bug (Lygus lineolaris)
These insects are brown to dark brown, somewhat oval, soft-bodied, about 1/4 inch (6 mm) long, with dark brown and yellow markings. Their feeding causes developing fruit to be malformed, knotty, and reduced in size.
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Mites
Both European Red Mite (Panonychus ulmi) and Two-Spotted Spider Mite (Tetranychus urticae) may affect apple, among others.
These eight-legged mites are very small, about 1/60 inch (0.4 mm) long, reddish or yellowish-green, feed on undersides of leaves causing foliage to have a blotched, pale, sticky appearance. From a distance, foliage may appear dusty. Heavy infestations can cause defoliation and reduce fruit size and quality.
