Cherry Fruit Flies

Rhagoletis species (Family Tephritidae) are pests of both sweet and tart cherries in Europe and North America. Adult flies are approximately 5 millimeters in length with distinctive black markings on wings, used to distinguish among species. Eggs are white, oval-shaped, approximately 1 millimeter long, and are inserted beneath the skin of ripening fruit by females. Eggs hatch into white maggots that feed within the fruit and drop to the ground to pupate. They construct golden brown puparia in which they will overwinter and emerge as adults the following summer. Yellow sticky traps hung in foliage of cherry trees are used to monitor adult flies; adding an ammonium-based bait can increase trap effectiveness. Organophos-phate-based insecticide sprays are considered to be the best method of control, although treatment must be made within roughly one week after detection of adults in traps.

Codling Moth

Codling moth, Cydia pomonella (Linnaeus), is a pest of apples and pears and has been found in plums, peaches, and cherries. Present throughout Europe, Asia, and North America, this small moth belonging to the family Tortricidae is approximately 10 millimeters in length with a wingspan of 12 millimeters. Adults can be distinguished by forewing coloration and patterns; forewings are gray with bronzed tips and crossed with alternating white and gray bands. Flattened, oval-shaped eggs are laid singly on fruit and foliage. Cream to pinkish larvae hatch from eggs and enter through the calyx end or side of the fruit, feeding internally for several weeks and destroying the fruit. Mature larvae crawl from fruit on the tree or from fallen fruit to pupation sites beneath the bark of trunks and limbs. Pupae are brown and found within silken cocoons. There are two generations throughout most of the world, with mature larvae overwintering within cocoons beneath bark, leaf litter, or other sheltered areas. Adult moths emerge the following spring, beginning during full bloom to late petal fall in apple. Monitoring with pheromone traps or with pheromone traps supported by a degree-day model to predict egg hatch are effective methods for timing of insecticide application. Traditionally, organo-phosphate-based insecticide sprays have been used for codling moth control, although alternatives do exist, such as insect growth regulators and mating disruption. Mating disruption prevents adult males from locating females; dispensers releasing a synthetic version of the female-produced sex pheromone are attached to many trees within the orchard and serve to confuse males as they attempt to locate receptive females in order to mate. This method of control can be used in orchards that are at least 2 hectares in size. No male moths should be captured in pheromone monitoring traps if mating disruption is working well; however, mating disruption effectiveness must be determined by assessing injury.

Fruit Piercing Moth

Fruit piercing moth, Eudocima species, belonging to the family Noctuidae, is found throughout the Pacific Basin, Asia, India, and Africa. This moth attacks both stone and pome fruit, as well as most tree and vine crops, including citrus and many vegetables. Adults are large moths, approximately 50 millimeters in length with a wingspan of 100 millimeters. Forewings are mottled brown, green, gray, and white, while hindwings are bright orange with black borders and an oval- or kidney-shaped mark. Eggs are laid on the undersides of leaves and bark of host plants belonging to the Fabaceae and Meni-spermaceae families. Larvae feed on foliage of plants and pupate within a cocoon spun between leaves. These insects are unusual in that the adult is the damaging life stage; adults use a strong proboscis, approximately 25 millimeters in length, to penetrate both unripe and ripe fruit to feed on juices at night. Fruit damaged by adults degrade rapidly and provide sites for secondary rot infections. Given that larvae of these moth species feed predominantly on plants outside orchards, traditional insecticidal control is difficult. Control of adult moths is especially challenging due to their large size and limited contact with treated plant surfaces. Further, adults regularly feed on fruit that are ripe or nearly so, negating the option for treatment near harvest with most conventional insecticides. Thus, control strategies include using smoke to mask odor of ripening fruit; smoke is deployed just before dusk to several hours after nightfall. A labor-intensive but effective method requires bagging or screening fruit in the field; this method is only economically feasible when fruit are of high value and/or easily accessible. Attract-and-kill bait stations are also being developed, and several parasitoids have been identified as potential biological control agents.

Leafrollers

Leafrollers are moth species belonging to the family Tortricidae; they can be found in all deciduous tree fruit-growing regions and are considered to be serious pests of stone and pome fruit. Adults are small, 8 to 30 millimeters in length, with broad, brown forewings and wingspans of approximately 30 millimeters, depending on species. Eggs are small, cryptically colored, and laid in masses on the upper surfaces of leaves. Larvae hatch and feed within shelters of folded or rolled leaves attached by silken threads. Larval feeding often includes fruit surfaces, leaving behind damage in the form of tiny holes or tunneling. There are multiple generations each year, and overwintering stages are either larval or pupal depending on species. Monitoring with pheromone traps to capture adult males and scouting for larvae based on degree-day accumulations are useful tools for timing insecticide sprays. Organophosphate- and carbamate-based insecticides traditionally have been used for control, although insect growth regulators and other newer insecticide chemistries are now available and being used.

Oriental Fruit Moth

Oriental fruit moth, Grapholita molesta (Busck), is a pest of stone fruit, and more recently apples and pears, and is found throughout the world. This small grayish moth species is approximately 5 millimeters in length with a wingspan of 10 to15 millimeters and belongs to the family Tortricidae. Flattened, oval-shaped, lightly colored eggs are laid singly on undersides of leaves or on twigs and in later generations, directly on fruit. Larvae are often confused with those of the codling moth; they can be differentiated by the presence of an anal comb on the last abdominal segment of oriental fruit moth larvae (Figure I1.1). Full-grown larvae overwinter in silken cocoons on trees within bark crevices, beneath groundcover, in weeds, or in orchard trash. Larvae pupate the following year in spring, with adults being found between pink bud stage and bloom, depending on cultivar and location. There are multiple generations per year, with the number completed depending primarily on temperatures experienced in a geographic region. First-generation larvae bore into new growth stems, resulting in damage to terminals, referred to as "flagging," while in later generations, larvae bore directly into fruit to feed internally, leaving signs of injury that include exuded gum and frass. However, if larvae enter fruit from inside the stem, there may be no external evidence of entry or injury. Monitoring methods include at least two pheromone traps per orchard to capture adult males and the use of a degree-day egg hatch model based on a biotic point (biofix) of first sustained adult catch in pheromone traps. Organophosphate-based insecticide programs have been the basis of oriental fruit moth control, although mating disruption has also proven promising for this species in orchards of at least 2 hectares in size.

FIGURE I1.1. Anal comb (200x) on the last abdominal segment of an oriental fruit moth larva, differentiating it from a codling moth larva (Source: Courtesy of Henry W. Hogmire Jr., West Virginia University, Kearneysville, WV.)

Plant Bugs and Stink Bugs

Species of plant bugs (Family Miridae), especially Lygus species, and stink bugs (Family Pentatomidae) are pests of stone and pome fruit throughout the world. Although adults and nymphs feed on many herbaceous plants (especially legumes), they also will feed regularly on deciduous tree fruit and shoots. In stone fruit, feeding injury prior to shuck split results in flower and fruit drop, while feeding on fruit before pit hardening primarily causes catfacing injury. Later-season feeding results in additional surface blemishes, water-soaked areas, and gummosis. In apples, early season, prebloom feeding results in bud abscission, while feeding after fruit set results in slight dimpling to deeply sunken, distorted areas. White sticky, rectangular traps hung from trees have been used to monitor tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), in apples, but not as successfully in stone fruit. Sweep sampling using a net in groundcover and limb jarring over a beating tray are good methods for sampling bugs in an or chard. Weed control, mowed grass, and clean cultivated aisles all help reduce both plant bug and stink bug populations. Prebloom insecticide sprays are often used to help control bugs early in the season.

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