Insects Attacking Grape Foliage
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Japanese Beetle, Popillia japonica Newman   

Description and Life Cycle

The adult beetles feed on the foliage and fruits of more than 250 kinds of plants, but grape is one of the preferred hosts.  The larvae are C-shaped grubs found in the soil, and are serious pests of grass roots.  The adult beetle has a shiny, metallic-green head and thorax, and coppery-brown wing covers.  Tufts of white hairs are located along the sides of the body.  Adult beetles are about 1/2 inch long.

 

This insect overwinters as a larva below the soil surface.  Larvae feed principally on grass roots.  During late spring, larvae move closer to the soil surface and complete their development; adults emerge in late-June or early-July.  Eggs are laid in the thatch layer of soil and take 10 days to hatch.  There is one generation per year.

Rastal pattern for Japanese beetle larva.

 

      Life cycle of the Japanese beetle in Ohio.

       Adult beetles emerge from the ground in June and July, and begin feeding upon foliage.  Mating occurs at this time and eggs are laid in the ground.  Eggs hatch in August and young grubs begin feeding on plant roots.  Grubs continue to feed and grow until cold weather, at which time they tunnel 3 to 12 inches down and make overwintering cells.  In the spring when soil begins to warm, grubs move toward the surface where additional feeding may occur before pupation in May.

Damage Symptoms

The adults feed on the leaves of both wild and cultivated grapevines.  Beetles prefer foliage exposed to direct sunlight and often are seen clustered together feeding on tender vegetative parts.  Vines with thin, smooth leaves, such as French hybrids, are preferred over those with thick, pubescent leaves, such as Concord.  Concord vineyards rarely need special control sprays for Japanese beetles.  On the other hand, French hybrids and other thin-leaved cultivars require frequent inspection to prevent damage.  Damaged leaves have a laced appearance, and severely affected leaves will drop prematurely.

Management

There is no economic threshold on the number of beetles or amount of damage that requires treatment.  If a susceptible cultivar is being grown and growers previously have experienced high populations of Japanese beetles, an insecticide should be applied when beetles emerge and thereafter as needed.

Monitoring

 Japanese beetle lure and trap is available for monitoring this pest, however these beetles are easily detected while walking through the vineyard and if skeletonizing of leaves becomes evident, thin leaved cultivars may need to be protected with an application of insecticide.  The usual threshold for making a spray application is about 15% of the leaves damaged. 

Control

Insecticide is usually applied when feeding is apparent on most vines and skeletonized leaves are found.  Spot treatment is adequate in some cases.  An insecticide with long residual activity is needed when beetle populations are high.  Repeated applications may be needed to control new beetles flying in from surrounding areas.

A microbial insecticide is available to control Japanese beetle grubs in turf, although it is slower acting and more expensive than conventional insecticides.  This substance is bacterial in nature and causes milky spore disease within the grub stage of development.  This microbial insecticide can not be relied upon to protect grapes from Japanese beetle. 

Current pesticide recommendations may be found at http://www.hort.purdue.edu/hort/ext/extpubs.shtml

 

Grape Phylloxera, Daktulosphaira vitifoliae (Fitch)

Description and Life Cycle Phylloxera is one of the most destructive grape pests worldwide.  This small aphid-like insect has a complex life cycle that involves survival on the roots throughout the year, and on the leaves during the growing season.  The sequence of events in the life cycle is different for the foliar and root forms of this insect.  The foliar form survives the winter as an egg under the bark of the grapevine.  Asexual, wingless forms hatch in the spring and crawl onto the new leaves, where they develop galls.  Young crawlers settle on the upper surface of immature leaves, causing galls to form on the under surface of the leaves.  The only opening in a gall is to the upper leaf surface.  Once mature, the female begins to lay eggs within a gall.  Nymphs hatching from these eggs crawl to new leaves at shoot tips, settle on the leaves, and form new galls.

In the case of the root form of grape phylloxera, the insects overwinter as immature forms on the roots.  These forms mature in the spring and produce eggs that hatch into nymphs.  The nymphs then start new galls on the roots.  Winged forms develop in the spring, summer or fall and emerge from the soil to lay eggs on stems.  These eggs hatch and produce the true sexual forms that produce the overwintering eggs laid under the bark.  Several generations of each form of phylloxera may occur each season.  Although the two forms behave differently, both belong to the same species of phylloxera that occurs on the leaves and roots of grapes.

Damage Symptoms

The insect forms galls on the leaves and roots of grapevines.  The vine will die if its roots become heavily infested with phylloxera.  If leaves become heavily infested, premature defoliation and retarded shoot growth may result.

Management

In many areas of the world, susceptible cultivars are grafted onto resistant rootstocks to prevent damage by the root form.  However, the foliar form still may occur in such cases.  Currently only one insecticide is labeled for the foliar form of grape phylloxera.  There are some natural predators which feed upon the foliar form of grape phylloxera, but none of these provide adequate control of the pest.  There is no known completely successful chemical control for the root form of gape phylloxera.  Eastern growers usually do not have a problem with the root form of the phylloxera.   

Monitoring

Phylloxera is usually spotty in Ohio vineyards, so identifying these areas within your vineyard is important.  Spot treatment may be all that is required to control this pest.  To identify the location and extent of phylloxera within a vineyard, one should begin scouting for infested leaves after shoot length has reached five inches.  Young galls will be forming on the underside of the terminal leaves, they are not easily noticed early in the season with out taking the time to inspect the leaves closely.  These galls should not be confused with grape tumid galls, commonly called the grape tomato gall.  Tumid galls have a smooth outer surface and take on a reddish tomato like appearance whereas the grape phylloxera gall is green in appearance except early in the season when young grape leaves tend to have more of a reddish cast to them.  The gall itself has a rough looking surface rather than the smooth surface of the tumid gall.  Tumid gall is present but not a problem in Ohio vineyards.

Control

Native American grapes tend to have resistance to grape phylloxera and are not a problem, however French hybrid and vinifera grapes are usually very susceptible and control of phylloxera on these cultivars is recommended.  One can not usually completely eradicate phylloxera from a vineyard that is already infested but can take measures to keep the infestation at a tolerable level.  Control of the foliar form of phylloxera may be achieved by applying insecticide at bloom and again 10 to 14 days later.  Late season treatment of grape phylloxera is not effective and is a waste of time and money.  Early season control of this pest is critical. 

Current pesticide recommendations may be found at http://www.hort.purdue.edu/hort/ext/extpubs.shtml 

 

Leafhoppers

Potato Leafhopper, Empoasca fabae (Harris)

Description and Life Cycle

The potato leafhopper, a sucking insect, feeds sporadically on grape foliage.  The adult leafhopper is pale to bright green, wedge-shaped and about 1/8 inch long.  The adults are very active, jumping, flying or running when disturbed.  The immature forms, or nymphs, are pale green and wingless.  They run forward, backward or sideways rapidly when threatened.  The potato leafhopper feeds on more than 200 plant species.

The potato leafhopper does not overwinter in areas north of the Gulf States.  Each year large numbers of potato leafhoppers are carried to northern areas by warm spring air currents.  Injury to grapes occurs when the adults fly into vineyards and feed on the leaves.  Toxins injected while feeding cause leaves to cup and be misshapen.  These leaves are often in the top of the vine and are quite obvious, especially at the end of the growing season.

Eastern Grape Leafhopper, Erythroneura comes (Say) 

 

 

 

 

Three-banded Leafhopper, E. tricincta Fitch

 

 

 

 

Virginia Creeper Leafhopper, E. ziczac Walsh

These are three of the most common leafhoppers found on grapes in Ohio and they belong to the same genus Erythroneura.  These three species vary in their coloration and markings. 

The adults of these leafhoppers are about 1/8 inch long.  E. comes is pale yellow or white with yellow, red, and blue markings.  Overwintering adults are often nearly all red.  E. tricincta is brown and black with touches of orange on the wings.  E. ziczac is pale yellowish or white with a zigzaz stripe down each wing and cross veins distinctly red.

The biology of these three species is similar.  They overwinter as adults in sheltered places such as the remains of old plants.  During the first warm spring days the leafhoppers become active, and they feed on the foliage of many different plants until grape leaves appear.  Eggs are deposited under the leaf epidermis; they hatch in about two weeks.  The immature leafhoppers, or nymphs,  are wingless; they remain and feed on the leaves where they hatch.  Nymphs molt five times, then transform into adults.  There are two or three generations of leafhoppers each season.

 

Damage Symptoms

Adults and nymphs feed on leaves by puncturing the leaf cell and sucking out the contents.  Each puncture causes a white blotch to appear on the leaf.  In heavy infestations, the leaves turn yellow or brown, and many will fall off.  Feeding by these leafhoppers may reduce the photosynthetic capacity of the plant, and the quality and quantity of the fruit may be affected. 

Grapevines can tolerate populations of up to 15 insects per leaf with little or no economic damage.  However, heavy leafhopper feeding may result in premature leaf drop, lowered sugar content, increased acid and poor coloration of the fruit.  The sticky excrement (honeydew) of the leafhoppers, affects the appearance and support the growth of sooty molds.  Severely infested vines may be unable to produce sufficient wood the following year.  Damage to the vine can be serious if infestations are allowed to persist unchecked for two or more years.

Management

Weeds and trash in and around a vineyard is a source of leafhoppers.  If this material is cultivated before spring the adults loose their protection and feeding sites, although in areas with extensive agriculture this practice has less value as the adults will just move to an adjacent crop or weedy area.  

Certain cultivars are likely to suffer higher leafhopper populations than others.  Wine and table grape varieties fit this criteria.  Moreover, late producing cultivars are more likely to favor leafhoppers than early maturing cultivars.

Monitoring

Vigorous vines are preferred by leafhoppers.  The heaviest populations are normally found on end vines and on outside rows.  This is partly because these vines are usually the most vigorous and therefore the most attractive.  It also is partly because of the border or boundary effect.  Vigorous vines fortunately can tolerate the highest populations. 

Sampling for leafhoppers should be done at 10 days post-bloom, third week in July and again the third to fourth week of August.  This is approximately the same time one should be assessing grape berry moth risk and both surveys may be conducted at the same time. 

 

Ten Days Post-bloom - Only adult leafhoppers are present at this time of the year, so it is not necessary to count them.  If leafhoppers are present, you should see stippling damage on the lower "sucker" leaves and interior leaves of the grape canopy.  By shaking the vines adult leafhoppers if present will fly around the vine.  If stippling damage is present throughout the vineyard an application of insecticide is recommended to prevent later damage from occurring.  Early season damage may indicate that populations may potentially build up to damaging levels later in the season.  Vineyards that are at high risk for grape berry moth usually apply insecticide at this time so scouting for leafhoppers at this time is not necessary. 

Third Week in July - By mid-to-late-July first generation nymphs are present and feeding on the undersides of grape leaves.  At this time, the need to apply an insecticide for leafhopper control should be determined on a block by block basis.  Sampling for grape berry moth and leafhoppers can be done with a single pass through the vineyard. 

The first step in evaluating leafhopper damage is to look for stippling on leaves while you are doing counts of grape berry moth damage.  Most damage will be found on the first seven leaves from the base of the shoot.  If no stippling or minimal stippling is visible on the leaves, there is no point in counting how many leafhoppers are present.  If moderate to heavy stippling is visible, then it is necessary to do counts of leafhopper nymphs to determine if damage levels warrant treatment.  The sampling procedure for leafhoppers requires counting all leafhoppers on the undersides of the third through seventh leaves of one shoot on each of five vines.  Sampling for leafhoppers should take only a few minutes per vineyard. 

Late August - In years when leafhoppers do build up to damaging levels in vineyards, it is most common for them to do so in late August.  Vineyards with greater than 10 leafhoppers per leaf should be treated at this time.  If there is very little visible stippling, sampling will not be necessary.  Vineyards that had insecticides applied to them earlier in the season will probably not need treatment at this time.  In Ohio we experience more of a problem with leafhoppers on the islands in Lake Erie and in vineyards near Lake Erie.

Control

Leafhoppers have few natural enemies.  Cold and wet weather conditions in spring and fall are damaging to leafhopper populations, as are wet winters.  Cultivation and clean-up of adjacent weedy land in the fall will eliminate favorable overwintering sites in and near a vineyard. 

When high populations of leafhoppers are encountered an application of a contact insecticide may be required.  In order to obtain good control of leafhoppers complete coverage of the undersides of the leaves is important.  Coverage of the fruit is of secondary importance. 

Current pesticide recommendations may be found at http://www.hort.purdue.edu/hort/ext/extpubs.shtml

 

Grape Plume Moth, Geina persicelidactylus (Fitch) (Lepidoptera: Pterophoridae)

The grape plume moth overwinters in the pupal stage. Adult moths emerge during the spring and lay eggs on grapevines. Hatched larvae feed on the upper grape leaf surfaces. Typically, a grape plume moth larva folds and webs the edges of a terminal leaf together and feeds within the fold. The larva is yellow with white hairs and about 5/8 inch long when fully grown. The adult moth is light brown with whitish markings and is 1/2 inch long. There is one generation each year.

Plume moth larvae rarely occur in large enough numbers in commercial vineyards to justify control measures.

Current pesticide recommendations may be found at http://www.hort.purdue.edu/hort/ext/extpubs.shtml

 

Grape Sawfly, Erythraspdes vitis (Harris) (Hymenoptera: Tenthredinidae)

The grape sawfly is a small, black, wasp-like insect that lays its eggs on the undersides of terminal grape leaves. The larvae that hatch from these eggs feed in a characteristic side-by-side manner at the edge of the leaf. Only the heaviest leaf veins are not eaten. When the larvae are fully grown, they drop to the ground, form cocoons and pupate. Two generations may occur in a single season.

Damage caused by the grape sawfly rarely achieves economic proportions.

Current pesticide recommendations may be found at http://www.hort.purdue.edu/hort/ext/extpubs.shtml

 

 

Eight-spotted Forester, Alypia octomaculata (Fab.) (Lepidoptera: Nocmidae)

The larva of the eight-spotted forester feeds on grape foliage; it devours everything except the heaviest veins and leaf petioles. The coloration of the larva is distinctive: black, white, orange and yellow. (Note similarity between forester larva and that of the following species, grapevine epimenis.) The larva, when fully grown, measures 1-1 1/4 inches in length. Largescale infestations are not common; however, small numbers of the larvae usually occur in most vineyards, causing some defoliation of the vines.

The eight-spotted forester overwinters as a pupa. Adult moths begin to emerge in May. A moth of this species is black, with a wingspan of 1-1 1/2 inches and a body length of about 5/8 inch. Each forewing has two yellow spots, each hind wing has two white spots and the thorax has a yellow stripe on each side. Eggs are laid on grape shoots and leaves. The larvae hatch and start to eat the foliage. They complete development by July, drop to the ground and pupate in tunnels they construct in old wood or trash just beneath the soil surface. Moths emerge during late July and August and lay eggs again. There may be two generations, or only a partial second generation, each year.

 

Current pesticide recommendations may be found at http://www.hort.purdue.edu/hort/ext/extpubs.shtml

 

 Grapevine Epimenis, Psychomorpha epimenis (Dury) (Lepidoptera: Noctuidae)

The larva of the grapevine epimenis is similar to that of the eight-spotted forester, and the two species are often confused in the field. The epimenis larva is bluish-white, and each segment of the body is marked by four transverse black stripes. There is a black-spotted red band on the eighth segment. The head, cervical and anal plates are red with black spots. The larva is about 3/4 inch long when fully grown.

The adult of the grapevine epimenis is a velvety-black moth. Across the outer portion of each front wing there is an irregularly shaped white patch.  On each hind wing there is a large, smooth-shaped orange-red or brownish-red patch. This" moth is about 7/8-1 inch in length.

Epimenis moths emerge in the spring after overwintering as pupae.  The female moth lays eggs on or near the new foliage. Larvae emerge and construct an enclosure of terminal leaves by drawing the leaves toward each other and tying them together with silk.  The caterpillar feeds within the shelter.  A single larva may construct several enclosures.

By early to mid-June the larva completes its development. The mature burrows into soft wood or any other suitable medium and pupates. There is only one generation per year.

Current pesticide recommendations may be found at http://www.hort.purdue.edu/hort/ext/extpubs.shtml

 

Grape Leaf Folder, Desmia funeralis (Hubner) (Lepidoptera: Pyralidae)

Damage caused by larvae of the grape leaf folder is usually minor in vineyards under a regular spray program for other insect pests. The larva, a pale green caterpillar about 1 inch long when fully developed, either folds or rolls a leaf, ties the edges with silk and feeds on the upper surface, concealed within the fold. When leaves are rolled, the larva feeds within the free edge of the leaf. The result of such feeding is skeletonized leaves.

This moth overwinters as a pupa. During early May, adult moths emerge from the pupae. An adult moth has dark brown wings with a spread of about 9/10 inch. The wings have a white border; each forewing has two nearly oval white spots. Each hindwing has one white spot, which may be divided in the female. The body is black and is crossed by two white bands in the female and one white band in the male.

There are usually two generations of the grape leaf folder each year. The second generation, which occurs in August and September, is the most damaging to grape foliage.

Current pesticide recommendations may be found at http://www.hort.purdue.edu/hort/ext/extpubs.shtml

 

 

Spotted Pelidnota, Pelidnota punctata (L.) (Coleoptera: Scarabaeidae)

The adult spotted pelidnota is a reddish-brown beetle with three black spots on each wing cover, and one on each side of the prothorax is 3/4-1 inch long. The adult beetle feeds on grape leaves, skeletonizing them. Large-scale infestations do not occur on grapes.

The larvae feed and live in decaying hardwood stumps, roots and logs, and do not harm grapes. The life cycle of this beetle requires two to three years to complete.

If the beetles are present in a vineyard, they are normally in plantings adjacent to wooded areas.

Current pesticide recommendations may be found at http://www.hort.purdue.edu/hort/ext/extpubs.shtml

 

Green Fruitworms (Lepidoptera: NoctUidae)

The most common species of fruitworm known to feed on grape is the pyramidal fruitworm, Amphipyra pyramidoides (Guenee). Two other species,

Lithophane antennata (Walker) and Orthosia hibisci (Guenee), also feed on grape foliage.

The pyramidal fruitworm overwinters in the egg stage. Near the end of April, larvae emerge from these eggs and proceed to feed on the new grape foliage. By mid- to late June, the larvae are fully developed. They either crawl or drop to the soil surface and manufacture a cocoon of silk and debris. During the first part of July, adult moths emerge; these moths do not lay eggs until about the end of September. Eggs are placed individually or in small masses on old canes.

The larva of the pyramidal fruitworm is green with a yellow line along each side of the body. It is 1/2 inch long when fully developed.

Fruitworms do not ordinarily occur in large enough numbers to require control.

Current pesticide recommendations may be found at http://www.hort.purdue.edu/hort/ext/extpubs.shtml

 

Grape Leaf Miner, Antispila viticordifoliella Clemens (Lepidoptera: Heliozelidae)

The larva of the grape leaf miner is a small caterpillar that feeds between the upper and lower leaf surfaces. When the larva is fully developed, it pupates within the area of the leaf where it has been feeding; this section eventually falls out, leaving a hole in the leaf.

The grape leaf miner is not an economically important insect; however, small numbers usually occur in vineyards, particularly in abandoned and backyard plantings.

Grape leaf damaged by larva of the grape leaf miner.  The leaf miner larva feeds between the upper and lower leaf surfaces. The section of the leaf damaged in this manner eventually falls out.

Current pesticide recommendations may be found at http://www.hort.purdue.edu/hort/ext/extpubs.shtml

 

 

Gall Midges (Diptera: Cecidomyiidae)

Grape Tomato Gall, Lasioptera vitis Osten-Sacken

Grape Blister Gall, Cecidomyia sp.

Grape Tube Gallmaker, Cecidomyia viticola Osten -Sacken

Several species of small flies, or midges, are known to cause galls on various parts of grapevines. The adult flies lay their eggs either on or in leaves, leaf petioles, tendrils or cluster stems. Fleshy or blister type galls, depending on the species of fly, are formed when the eggs are deposited inside the plant or when the larvae emerge from the eggs and begin to feed. When these larvae are fully grown, they leave the galls, fall to the soil and pupate. Some species may have more than one generation per year.

The grape blister gall is caused by a midge, Cecidomyia sp. This gall may be pink or green and about 1/8 inch in diameter. It occurs on leaves, and a single leaf may contain several galls. The grape tomato gall is caused by several midges, the more common one probably being Lasioptera vitis Osten-Sacken. The tomato gall is a green or red leaf or tendril gall, 1/4-3/4 inch in diameter. The midge Cecidomyia viticola Osten-Sacken is responsible for the formation of the grape tube gall, a conical red or green leaf gall 1/4 inch long.

These gall-forming flies do not often inflict economic injury on grapevines. Removing the galls from the vines mayor may not be of some benefit in reducing the numbers of flies present in a vineyard. Such an action should be taken before small holes are seen in the galls as this indicates that the larvae have already emerged.

 

 

 

Grape blister galls.

                                                                                                    

 

 

 

Grape tomato galls and larvae

 

 

 


Grape tube galls.

       

Current pesticide recommendations may be found at http://www.hort.purdue.edu/hort/ext/extpubs.shtml

 

Grapevine Aphid,  Aphis illinoisensis Shimer (Homoptera: Aphididae)

The grapevine aphid is rarely a serious pest of cultivated grapes. The aphids pass the winter in the egg stage on viburnum. Hatching begins in early spring. Initially, wingless generations are produced, after which winged individuals make their appearance and fly to vineyards. Colonies of the aphid develop on the young shoots and leaves. The aphids are dark brown and the adult females are about 1/10 inch long. In the fall, winged aphids again develop; they return to viburnum and give rise to the egglaying females.

There are numerous natural enemies of the grapevine aphid, including ladybird beetles, lacewings, syrphid fly larvae and parasitic wasps, which usually exert some degree of control on the aphids. This insect normally does not pose a serious threat to grapevines.

Current pesticide recommendations may be found at http://www.hort.purdue.edu/hort/ext/extpubs.shtml

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