Numerous insects are pests on peach trees in South Carolina. They cause damage to the peach flowers, fruit, twigs, limbs, and trunk. Some of the most common of these are plum curculio, Oriental fruit moth, peachtree borer, lesser peachtree borer, shothole borer, catfacing insects, scale, Japanese beetle, and the green June beetle.
As a result of the need to control some serious insect pests as well as disease organisms, individuals who grow peaches in their backyard for home use often discover that obtaining acceptable quality fruit requires more specialized care than they can give. It should be noted that without the application of well-timed pesticides, it is common for insect pests and disease to ruin the entire crop as well as damage the tree(s).
Several all-purpose fruit sprays are on the market for homeowner use. These materials contain insecticides and a fungicide, which will control most insects and diseases seen in a home orchard fruit tree situation. See Table 1 for examples of brands and products. As with any pesticide, read and follow all label directions and precautions.
Aside from pesticides, homeowners can follow such cultural practices as proper sanitation to reduce insect pests significantly. Sanitation includes quickly removing and destroying dead, diseased, and damaged wood and fruit. The leaves, wood, and fruit often provide pests with places to complete their development or to survive the winter.
Although adequate insect control on peaches usually requires spraying trees, these sprays need to be timed accurately to be effective. Knowledge of the insect pests and their life cycles aids in identification, as well as the early diagnosis of a developing pest problem. While there are numerous insects that will feed on peaches, below are some of the most common insect pests of peaches that are found in South Carolina.
The adult plum curculio (Conotrachelus nenuphar) beetle is a mottled brown insect with a rough and warty body surface. It is about ¼-inch long and has a long, curved snout. Its immature stage is a grub (larva). A fully mature grub is legless, smooth-bodied, and up to ½ inch in length. It is yellowish to grayish in color and slightly curved with a brown head.
Both adults and grubs cause damage to peaches, as well as plums and other stone fruits, apples, and occasionally pears. The primary injury is caused by the adult female when she makes a crescent-shaped cut in the skin of the fruit to lay her eggs. This results in crescent or D-shaped scars on the fruit surface. Grubs feed inside the fruit and make it worthless. Later in the season both males and females damage the fruit by making round feeding punctures.
Plum curculio adults overwinter (survive the winter) under leaves, brush, and in other protected places near the orchard. Wild plum thickets within ¼ mile of an orchard can provide an alternate host for adults. The adults become active when average temperatures reach 50 to 60 ºF for three to four days or when the maximum temperature reaches 75 ºF for two or more days. This is usually about the time peach trees bloom. The first activity will be noticed on outside rows.
They feed on developing fruit and leaves and lay their eggs in the young fruit. Carefully inspect fruit on the outside orchard rows for egg-laying and feeding scars. Fruit infested shortly after bloom by the first generation drop to the ground. The larvae hatch and feed in the fruit. They leave the fruit, burrow into the ground and pupate (transform into the non-feeding stage where the larva changes into an adult). The first generation adults emerge from mid-June through July, move into the trees, and begin laying eggs. Fruit infected by the second generation remain on the tree until harvest. Again, the larvae feed for a while, drop to the ground, and pupate. The second generation adults emerge in the fall, move to the hibernation areas, and overwinter.
When disturbed, the adult plum curculio tends to fold its legs against its body and fall to the ground where it remains motionless for several minutes. This behavior can be used when trying to detect its presence. Place a light colored drop cloth on the ground under the tree and shake some branches. If present, the plum curculio will drop to the ground and be readily visible.
Control: Homeowners can achieve at least partial control by practicing good sanitation methods. These include picking up and destroying fruit on a weekly basis that drops early, as well as removing or cleaning up overwintering sites.
Chemical controls should be applied immediately after the flower petals fall to control the first generation. Three sprays are recommended: the first in mid-June, and the second at the end of June, and the third in early July in order to control the second generation adults. Homeowners can use malathion. This insecticide may be used individually or can be found in premixed home orchard spray products. See Table 1 for examples of brands and products. When using malathion, wait 3 between sprays and 7 days before harvest. Permethrin, lambda or gamma cyhalothrin, or cypermethrin may also be used to control plum curculio, but do not apply these products within 14 days of harvest. Repeated use of permethrin or lambda or gamma cyhalothrin may increase problems later in the season with scale or spider mite outbreaks. For organic management, a mixture of neem oil and pyrethrins is labeled for plum curculio management and may give some control. As with all pesticides, read and follow all label directions and precautions.
Though products are available at gardening stores for homeowners, many gardeners are not inclined to use pesticide applications for home fruit production. Instead, hobbyist gardeners may use bags to protect fruit from pests and diseases. Clemson University has tested and is promoting the use of specialty bags that, if used properly, allow for production of high quality fruit with very little pesticide input. The bags are recommended for use in a three-step fashion: (i) properly take care of the trees to minimize tree stress; (ii) protect fruit from pests and insects between bloom and the day of bagging; and (iii) enclose thumbnail-sized, green fruit (typically 3 weeks after bloom) with a specialty bag to be removed at harvest. For purchase information and use instructions, please see Clemson Fruit Bags or simply google this page using the keywords “Clemson Fruit Bags”
Oriental Fruit Moth
The Oriental fruit moth (Grapholita molesta) is grayish-brown and has a wingspan of about ½ inch. It is active at night. When first hatched, its caterpillar (larva) is about 1/16-inch long and white with a black head. The mature caterpillar is about ½-inch long, has six distinct legs, and is pinkish with a brown head. The caterpillar is a pest of peaches and other stone fruits as well as apples, pears, and some ornamentals in the rose family.
In South Carolina, there are six or more generations of Oriental fruit moth per year. This pest overwinters as mature larvae inside cocoons, which are located in protected areas on the tree or in debris near the base of the tree. In early spring, the larvae pupate (transform into the non-feeding stage where the larva changes into an adult), and adults begin to emerge around the time of bloom. The adults lay eggs from which larvae hatch.
These first-generation caterpillars bore into new growth at the tips of peach tree branches. This activity causes the branch tips to wilt (also known as “flagging”) and die back. Later in the season, after the branch tips harden, caterpillars enter and feed inside the fruit. While in the fruit and twigs, caterpillars are protected from insecticides. Good early season control of adult moths using insecticides will often provide control for the entire season.
Control: The presence of moths can be detected with the use of traps containing pheromones (synthetic insect attractants). Permethrin, lambda cyhalothrin, or malathion sprays should be applied if an average of more than 10 moths per trap occurs. Do not apply products containing malathion within 7 days of harvest or apply permethrin or lambda cyhalothrin within 14 days of harvest. Also, do not apply more than 8 applications of permethrin per season for all insect pests.
The peachtree borer (Synanthedon exitiosa), the lesser peachtree borer (Synanthedon pictipes), and the shothole borer (Scolytus rugulosus) are all pests of peaches that bore, or tunnel, inside the peach tree. Of these, the peachtree borer and lesser peachtree borer are the more serious pests. They are found on most cultivated and wild stone fruits, including some ornamental shrubs, such as flowering peach, cherry, and plum. It is the larvae of these insects that damage peach trees.
Peachtree Borer: Peachtree borers, also known as greater peachtree borers, are clearwing moths and are often mistaken for wasps due to their appearance and behavior. The adult female is a metallic blue-black color except for a red-orange band on the abdomen. The male is black with yellow stripes along the back at the base of each wing and narrow yellow stripes on the abdomen. The larva (immature stage) is about 1 to 1¼ inches long when fully grown. It is creamy-white with a brown head.
The larva of the peachtree borer attacks the tree at the base and may be found feeding from the main roots to about 10 inches up onto the trunk. Masses of gum mixed with frass (gritty, sawdust-like insect excrement) are the primary symptoms of an attack. Young trees can be killed by a very small number of larvae. Older trees can tolerate more larvae.
The peachtree borer overwinters (survives the winter) as larvae. It has one generation per year. Some adults begin emerging in late May, although peak emergence is in mid-to-late August. Wounds and rough bark are favorite sites for egg laying. About two weeks after the eggs are laid at the base of the tree, the small larvae hatch and burrow into the bark, where they begin to feed. They stop feeding when cold weather comes and resume feeding the following spring.
Control: Since the peachtree borer causes the most severe damage to young trees, special care must be taken during planting to avoid damaging the bark. In light soils, the wind may make the tree move enough to make a gap between the trunk and the soil or abrade the bark. This is an excellent entry site for the larvae. Annual trunk sprays during August will generally keep the peachtree borer under control. Be sure to apply sufficient spray from the scaffold limbs to ground level so the bark is saturated and a small puddle forms at the base of each tree.
Homeowners can use permethrin sprays at the base of the trees for peachtree borer control. Do not apply these products within 14 days of harvest. See Table 1 for examples of brands and products. As with all pesticides, read and follow all label directions and precautions.
Lesser Peachtree Borer: The adults of the lesser peachtree borer are also clearwing moths. Both the male and female adult lesser peachtree borers resemble the male peachtree borer, except that they are somewhat smaller. The larva of the lesser peachtree borer is very similar to the larva of the peachtree borer but smaller.
The lesser peachtree borer attacks the trunk and main limbs. Again, the symptoms are oozing gum that contains frass. Heavy infestations can kill individual limbs or an entire tree.
Similar to the peachtree borer, the lesser peachtree borer overwinters as larvae. However, it has two generations per season and occasionally a third. Emergence of adults peaks in late April to mid-May and late July to mid-August. Cytospora cankers (a fungal disease), wounds, and previously infested areas are favorite sites for egg laying.
Control: The best control for the lesser peachtree borer is to keep the trees in a vigorous, healthy growing condition and to prevent mechanical injury. Prune out split or broken limbs and limbs with signs of borer damage where feasible. Destroy pruned wood before adults emerge in April by shredding or burning. Avoid spreading bacterial canker while pruning by dipping the pruning tool after each cut into a solution of one part household bleach to nine parts water.
As with the peachtree borer, annual trunk and limb sprays in August will help control the lesser peachtree borer. However, since there are two or more generations per year, it is difficult to get good control with insecticides because the first generation emerges while there is fruit on the tree. Homeowners can use permethrin for lesser peachtree borer control. Permethrin will last longer on trunks than most other insecticides. See Table 1 for examples of brands and products. Do not apply these products within 14 days of harvest. As with all pesticides, read and follow all label directions and precautions.
Shothole Borer: Shothole borers are small, cylindrical beetles. They attack many fruit trees, ornamental trees, and shrubs. Plants under stress are highly susceptible to shothole borer attack. Shothole borers attack the trunk and limbs. The entry holes look like the tree has been hit with fine birdshot. The adult beetle bores into the bark and then carves out chambers below the bark in which to lay eggs. The larvae feed on the bark. Occasionally, shothole borers may attempt to enter the twigs at the base of flower buds. This activity can destroy the buds.
The shothole borer overwinters as larvae. It has several generations per year. The adults emerge from the infested trees in April and May and move to new trees, especially those under stress from drought or disease.
Control: The best control for shothole borer is to keep the trees in a vigorous, healthy growing condition and to prevent mechanical injury. Prune out split or broken limbs and limbs with signs of borer damage where feasible. Destroy pruned wood before adults emerge in April by shredding or burning. Avoid spreading bacterial canker while pruning by dipping the pruning tool after each cut into a solution of one part household bleach to nine parts water.
Permethrin sprays that are necessary for other borers provide adequate control of adults. Do not apply these products within 14 days of harvest. See Table 1 for examples of brands and products. As with all pesticides, read and follow all label directions and precautions. With more than one generation per year, it is difficult to get good control with insecticides since the first generation emerges while there is fruit on the tree. There is no effective control for insects already in the tree.
Catfacing insects include the tarnished plant bug (Lygus lineolaris) and various stink bugs. The tarnished plant bug is oval and has a white triangle on its back in the “shoulder” area. It is brown and about ¼-inch long.
Stinkbugs are shaped like a shield. They vary in color from green to brown and in size from ½ to ¾ inch in length.
The tarnished plant bug and the stink bugs have needle-like mouthparts that they use for piercing and sucking. Initial feeding kills the fruit tissue at the feeding site, resulting in oozing from the fruit, which becomes deep dimples along the surface as the fruit grows. Minor damage is generally cosmetic, and the fruit is still edible. Severe damage creates large crevices and dimples (the “catfacing”) with tough, cork-like flesh in the fruit, which is not remotely appetizing.
While there are several native stink bugs found in the Southeast, a relatively new invasive species has also shown up. The Brown marmorated stink bug (Halyomorpha halys) is an exotic stink bug that can cause major damage to tree fruit, especially peaches. The adults are approximately 5/8-inch long with a mottled brownish-grey color. The next to last (4th) antennal segment has a white band, and there are black and white bands on several of the abdominal segments. What is unique about brown marmorated stink bugs is that they commonly overwinter inside houses and other dwellings and emerge in early spring. Once they emerge from overwintering, they immediately move to feed on available hosts. The brown marmorated stink bugs are especially problematic in peaches because, unlike the native stink bugs, even the nymphs feed on peaches. Thus, with two generations of brown marmorated stink bugs per season, they have the potential to feed on peaches all season long.
Tarnished plant bugs and stink bugs overwinter as adults in protected areas in or near the orchard. Winter annual weeds that begin to bloom in late winter are a major attractant for most of these insects, like the tarnished plant bugs and native stink bugs.
Control: Removing weeds and debris in the area will greatly enhance control of these insects. For chemical control, permethrin, lambda or gamma cyhalothrin, or cypermethrin are available in homeowner formulations. Do not apply these products within 14 days of harvest. See Table 1 for examples of brands and products. As with all pesticides, read and follow all label directions and precautions.
Various scale insects attack peaches. The most commonly seen are the white peach scale (Pseudaulacaspis pentagona) and the San Jose scale (Comstockaspis perniciosa). These immobile insects can rapidly decrease the vigor of peach trees, kill limbs, and ultimately kill the trees.
Scales are unusual insects in appearance. Adults are small and immobile, with no visible legs. Scales vary in appearance depending on age, sex, and species. The adult females typically produce a waxy covering that protects them from many insecticides. They feed on sap by piercing the leaf or stem with their mouthparts and sucking.
The adult female white peach scale is 1/16– to ⅛-inch in diameter. It is circular in shape and yellowish to grayish-white with a yellow or reddish spot. It will infest the bark, fruit, and leaves of peach trees. An infestation of white peach scale can result in stunting, leaf drop, and death of branches and potentially entire trees.
The white peach scale survives the winter as an adult female. The adult male is mobile and lives about one day. After mating, the female starts laying eggs in early April. The eggs hatch into nymphs (the immature stage that looks similar to an adult, only smaller). Nymphs, or crawlers, disperse along the tree branch for a few days before settling and beginning to feed. There are three generations per year.
The San Jose scale survives the winter as partially developed male and female adults. Development continues when the sap flow begins in the spring, and they become fully developed about the time the peach trees are in bloom. This species does not lay eggs but gives live birth to crawlers that immediately disperse over the tree. There are four to six generations per year.
Control: The adult female scales are difficult to control with insecticides because of their hard, waxy covering. Horticultural oil can be applied before budbreak when the temperature is above 40 °F. The oil sprays work by smothering the overwintering adult females, and they offer the best control when applied during the dormant season. Spray the trunk and limbs with a 2 or 3% oil solution to the point of run-off. Two sprays are best at 3 weeks and 1 week before bud swell. To make a 2% horticultural oil spray, add 5 tablespoons of oil per gallon of water.
If the scale problem is serious, fall applications applied during the first cool spell after full leaf drop should be considered. These oil sprays applied during the dormant season will also help control spider mite infestations, as they survive the winter on the bark.
Chemical control of only the crawlers only can be achieved with malathion, permethrin, lambda or gamma cyhalothrin, or cypermethrin. If spider mites become a problem, a 0.5% horticultural oil spray will suppress them. Do not apply a horticultural oil spray within 2 weeks of a captan (fungicide) spray. Table 1 has examples of insecticide brands and products.
Additionally, sprays for controlling scale should be applied about April 9, June 25, August 25, and October 8 in the Savannah Valley and Pee Dee regions, and about May 1, July 1, and September 1 in Piedmont. Do not spray insecticides during bloom. Do not apply malathion within 7 days of harvest, and permethrin, or lambda or gamma cyhalothrin within 14 days of harvest. Do not apply Bonide Complete Fruit Tree Spray within 21 days of harvest. As with all pesticides, read and follow all label directions and precautions.
Table 1. Insecticides for Peach Insect Pests.
|Pesticide Active Ingredient||Examples of Brands & Products|
|Horticultural Oil||Bonide All Seasons Horticultural Spray Oil Concentrate; & RTS
Ferti-lome Horticultural Oil Spray Concentrate; & RTS
Monterey Horticultural Oil RTS OMRI
Summit Year-Round Spray Oil Concentrate; & RTS
|Gamma-Cyhalothrin||Spectracide Triazicide Insect Killer for Lawns & Landscapes Concentrate; & RTS|
|Lambda-Cyhalothrin||Bonide Fruit Tree & Plant Guard (also w/ Boscalid & Pyraclostrobin – which are fungicides)|
|Cypermethrin||Gardentech Sevin insect Killer Concentrate; & RTS
Gordon’s Bug-No-More Lawn & Garden Insect Control Conc.
|Malathion||Bonide Malathion Insect Control Concentrate
Hi-Yield 55% Malathion Insect Spray
Ortho Max Malathion Insect Spray Concentrate
Spectracide Malathion Insect Spray Concentrate 50%
Southern Ag Malathion 50% EC
|Neem Oil & Pyrethrins||Ferti-lome Triple Action Insecticide, Fungicide, & Miticide Conc.; & RTS; & RTU
Ortho Tree & Shrub Fruit Tree Spray Concentrate
Monterey Fruit Tree Spray Plus RTS
|Permethrin||Bonide Eight Insect Control Vegetable, Fruit, & Flower Concentrate
Bonide Eight Insect Control Yard & Garden RTS
Hi-Yield Indoor/Outdoor Broad Use Insecticide Concentrate
|Combination Fruit Tree Sprays|
|Malathion, Carbaryl & Captan||Bonide Complete Fruit Tree Spray Concentrate|
|RTS = Ready to Spray (a hose-end spray bottle)
RTU = Ready to Use (a small premixed spray bottle)
Notes: Captan is a general-purpose fruit tree fungicide.
The Bonide Fruit Tree & Plant Guard can only be applied 5 times during the growing season because of the specific fungicides in the product. It also contains an insecticide.
To protect pollinating insects, do NOT spray any insecticides during bloom, and always spray late in the evening before dark.
Do not spray a horticultural oil spray within 2 weeks of a captan or sulfur spray.
For a general fruit tree spray schedule, please see IC 119 Insect & Disease Management for Home Grown Fruits & Nuts. For more information on peach diseases and control, please see HGIC 2209, Peach Diseases.