BANDED GRAPE BUG is a sporadic pest of grapes in the Finger Lakes and Lake Erie regions and does not require treatment in most years. Nymphs of this insect emerge in the spring and feed on flowers and young berries, using their sucking and piercing mouth parts. The nymphs range in size from 1/8- to 1/2-inch in length, depending on the stage. Injury by small nymphs, occurring between 3- to 5-inch shoot growth (around May 15) and early June, results in floret drop, reduced berry set, and fewer clusters. Subsequent feeding by larger nymphs and adults does not affect cluster development. Economic injury can occur when more than 1 nymph per 10 shoots are present. This injury only occurs in the early prebloom stages (between 5- and 10-inch shoot growth). Subsequent feeding by nymphs does not reduce berry set. Adults appear to be predaceous and do not cause injury to berries. Look for nymphs on grape clusters and shoot tips prior to the bloom period. They can be recognized by their long, banded antennae.

CLIMBING CUTWORMS are known to feed on grapes. Larvae hide in the soil litter below the grape trellis and climb onto vines on warm nights to feed on developing primary buds. Only during bud swell are cutworms able to inflict serious damage to a vineyard. To examine vines for cutworms, search under the bark and in the soil litter beneath a vine with damaged buds, or search the vine with a flashlight after dark.

EUROPEAN CORN BORER is an important lepidopteran pest of corn, but it is also known to feed on over 200 other plant species, including grapes. Corn borer problems are rare, but under some circumstances, may require management. They are usually found in Vinifera varieties, especially vines with excessive foliage or where vineyards are weedy or surrounded by corn, sorghum, sudan grass, or related crops. Young vineyards or nursery stock may be more seriously affected by borer injury than mature vines. The larvae vary in color, ranging from creamy to light gray to faint pink, with very small, round, dark brown spots on each segment and a dark-colored head capsule. After initially feeding on young leaves, larvae bore into canes. This weakens or kills shoots, especially when the larvae enter the middle or lower sections. Adult moths are a creamy yellowish-brown and approximately one inch long. Eggs are white and laid in masses resembling overlapping fish scales on the underside of leaves. Egg laying can occur in late May, late June to early July, or early August, depending on the genetic race of corn borer present. See the section on pest management schedules for minor insects (4.3) for pesticide recommendations and other comments.

EUROPEAN RED MITES are spider mites. Adult mites are small, dark red, and have eight legs. When viewed with a hand lens, the mites appear hairy because they have white spines called “setae.” Nymphs range in color from pale to dark orange. Both adults and nymphs pierce the leaf cells and extract plant juices. This leads to the characteristic bronze coloration, which impairs the photosynthetic capacity of the leaf. Two-spotted spider mites are often found in mixed populations with European red mites. Two-spotted spider mites are light in color with two black spots on their backs. Vinifera and French hybrid varieties appear to be the most susceptible to infestations, although native varieties can also develop large densities under some conditions. Mites may be found on the upper or lower leaf surface. Four to nine generations occur in a season. Susceptible vineyards in production areas prone to damaging infestations should be monitored, starting at the bud break stage, for presence of this pest. Although problems can develop at any time after bud break, pay particular attention to the 1- to 4-inch growth stage and the postbloom period, especially after early July. Given a head start, the vine can tolerate a fair amount of feeding damage on lower leaves. Heavy mite infestations early in the season can cause stunted, chlorotic shoots with small leaves and pinpoint necrotic areas on leaves. Later in the season, as shoot growth rate declines and the vine allocates more resources to fruit, mites may also have an increased capacity to cause damage. Infestations can be severe on Long Island and in southeastern Pennsylvania vineyards. Serious infestations in the Finger Lakes region have occurred more frequently in recent years. Problems with spider mites in the Lake Erie region are uncommon. Predatory mites, when present in the vineyard at sufficient densities, can provide excellent biological control of spider mites. Recent research indicates that frequent use of mancozeb fungicides reduces predatory mite populations, although mancozeb use does not necessarily lead to mite problems.

GRAPE BERRY MOTH is one of the most serious insect pests affecting grapes in New York and Pennsylvania. There are two and occasionally three generations of moths per season. Overwintered pupae emerge as adult moths in late May and lay eggs among the grape clusters. The larvae are small (up to 4/10-inch long) and feed internally in grape berries. External signs of moth feeding are the silk webs that tie several berries together. The larvae cut flaps in grape leaves and pupate inside, emerging as adult moths (wingspan is 0.5 inch). Timing of sprays is best accomplished using the grape berry moth risk assessment protocol. Bulletin 138 covers the risk assessment protocol in detail. See list of Cornell publications in section 2.5.

GRAPE CANE BORER is a small (3/8-inch), cylindrical brown beetle that bores into canes, leaving round entrance holes that are about 1/8-inch in diameter. Immature cane borers feed only on dead or dying wood, but adults can enter vigorous, live canes starting in late August. Tunneling can weaken canes causing them to break or die back. It can be particularly problematic when training young vines. Damage has been reported primarily in vineyards surrounding Keuka and Seneca Lakes in the Finger Lakes region of New York. Research in New York and Europe indicates that problems with grape cane borer are reduced if wood from pruning is removed and destroyed each year. Destruction of burn piles before late summer is recommended.

GRAPE LEAFHOPPERS overwinter in leaves and litter and enter vineyards in the spring and feed on sucker leaves. These overwintered adults generally do not cause serious damage. Depending on degree-day accumulations, one to two generations occur. Rapid population increases are most likely in hot, dry years. Both the adults and nymphs feed on the underside of grape leaves by piercing the tissue and sucking out the plant juices. Damaged leaves become mottled with yellow dots. A moderate infestation of grape leafhopper does not affect yield and quality significantly. The species of leafhopper found on Labrusca-type cultivars differ from those found on hybrids and Vinifera grapes. The Eastern grape leafhopper, Erythroneura comes, is found on Labrusca cultivars such as Concord, Niagara, Catawba, Delaware, and other American varieties. Hybrids and Vinifera grapes are infested by other Erythroneura leafhopper species, principally Erythroneura bistrata. This distinction may be important in the Finger Lakes, where resistance of Eastern grape leafhopper to carbaryl is suspected in isolated vineyards. The species of leafhoppers found on hybrid and Vinifera grapes are not affected by resistance at this time.

GRAPE PHYLLOXERA are minute insects with a complex life cycle. Two forms of phylloxera occur within the same species, and several generations of each may occur in any given year. The root gall form feeds on the outside of galls or on swelling on the roots. Loss due to this form can be substantially reduced by grafting to a phylloxera-resistant rootstock. This grafting will not affect injury caused by the leaf gall form of the phylloxera. The leaf gall form lives inside galls on the underside of grape leaves. There is a wide range in the susceptibility of grape varieties to both forms of phylloxera. Although V. vinifera roots are especially vulnerable to phylloxera, recent research indicates phylloxera can also feed on L. labrusca roots and reduce vine vigor. Examine foliage on a weekly basis before and after bloom. Apply spray when first galls are detected; spray again 10–12 days later if new growth becomes infested. Many varieties can withstand extensive galling.

GRAPE ROOTWORM is a beetle that feeds on grape foliage as an adult, producing chain-like feeding patterns on the leaves. Immature stages, however, feed on grape roots, and if left untreated, can cause serious damage and vineyard decline over a period of years. Grape rootworm adults begin appearing in vineyards in mid- to late May. They lay eggs on the vine trunk. After the eggs hatch, the larvae crawl into the soil and attach themselves to grape roots. They remain there for 1–2 years while completing their development. An insecticide application made when chain-like feeding symptoms appear throughout a vineyard will control adults before they lay eggs. This pest appears sporadically and does not require treatment every year.

GRAPE ROOT BORERS are clear-winged moths that strongly resemble paper wasps. At present, in this region they occur only in southern and eastern Pennsylvania. Larvae feed on grape roots for a 2-year period. Mature larvae burrow to just below the soil surface, spin a dirty brown silk cocoon, and pupate. Adults emerge in mid- to late summer, mate, and lay eggs beneath vines. The eggs hatch and reenter the root system. There is no registered method for controlling the subterranean stages of this insect. For preventive control, apply a soil barrier of chlorpyrifos in a 5-foot-wide band beneath the trellis. This barrier must be in place when adult grape root borers are flying. Careful monitoring for pupal cases on soil surface beneath vines will reveal when pupation is occurring, and thereby aid in timing application of the soil barrier.

GRAPE FLEA BEETLES OR STEELY BEETLES are small (3/16-inch) bluish-black beetles that damage vines by feeding on small grape

Pest Management Guidelines A Cornell Cooperative Extension Publication	New York and Pennsylvania Pest Management Guidelines for Grapes
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