Tree Fruit Insect Pest - Peachtree Borer

The peachtree borer, Synanthedon exitiosa, is primarily a pest of peach and nectarine trees, but it also attacks apricot, cherry, and plum.
Tree Fruit Insect Pest - Peachtree Borer - Articles
Tree Fruit Insect Pest - Peachtree Borer

Most adults emerge and lay up to 500 eggs during July and August on tree trunks, in cracks or under bark scales, and in soil near the tree trunk. Photo by G. Krawczyk.

This native American borer has been known since colonial times and is a pest wherever peaches are grown.

Description and life cycle

Adults resemble wasps when flying and are often mistaken for them. Female moths are dark blue with a broad orange band around the body and forewings darker than the clear hind wings. The male is smaller and has three to four narrow yellowish bands across the body; both pairs of wings are clear. Males of peachtree borer have black scales on the top of the head between the eyes and yellow scales between the antennae. This combination differentiates them from males of lesser peachtree borer, which have yellow scales between the eyes and black scales between the antennae. Larvae are white with a brown head and 1.5 inches long at maturity.

Overwintering

Peachtree borer has a single generation per year, but it can result in severe losses if not managed correctly. This borer overwinters in a wide range of larval stages. Larvae become active and resume feeding in April, with larger larvae completing their feeding during June and July. Most adults emerge and lay up to 500 eggs during July and August on tree trunks, in cracks or under bark scales, and in soil near the tree trunk. Eggs hatch in 10 days and young larvae feed on tree bark, working their way into the trunk as they become larger. One of the first signs of peachtree borer attack is a mass of gum exuding from the trunk base approximately 3 inches above to 1 foot below soil surface. This gum mass contains bits of wood chips, sawdust, and frass produced by the feeding larvae. Burrowing larvae weaken the tree, resulting in lower fruit production or, if borers are numerous, death of the tree. Neglected trees or those suffering from drought or winter injury are most likely to be infested.

Monitoring

Pheromone trap capture peaking at less than ten moths per week generally indicates that this species is not causing losses. If any evidence of feeding is observed on trees up to three years old, a treatment is warranted. Older trees with more than one larva per tree should be treated.

Cultural management

Maintain healthy trees.

Mating disruption

Certain mating disruption pheromone dispensers are registered for the control of peachtree borer on peach, nectarine, cherry, prune, plum, and apricot. Dispensers release pheromones for 100 to 120 days and should be placed in the orchard before moth emergence in early June. For effective control of peachtree borer, use the recommended number of pheromone dispensers per acre. To improve the efficacy of mating disruption, distribute the dispensers uniformly throughout the entire block.

Chemical management

Roots should be dipped in an insecticide solution before planting. Protective trunk sprays should be applied in the summer from the lower scaffold branches to the soil line. Soak the bark to runoff, so that a puddle of solution can be seen at the base of the tree. Specific chemical recommendations for home gardeners are in Fruit Production for the Home Gardener, and recommendations for commercial growers are in the Penn State Tree Fruit Production Guide.

Authors

Insect plant interactions Integrated pest management Biological control Tree fruit insect pests Insects rearing Laboratory and field bioassays Invasive insect pests Pesticide resistance

More by Grzegorz (Greg) Krawczyk, Ph.D.