How to Manage Pests

Pests in Gardens and Landscapes

American plum borer—Euzophera semifuneralis

Young larvae are white with a large, dark brown head. Mature larvae are about 1 inch long, dusky white, pinkish or dull green in color. The forewings of the adult moth are gray with brown and black markings. The wingspan is about 1 inch long.

Identification of species | Life cycle

Damage

Larvae bore into the tree leaving reddish orange frass and gum pockets. The boring is most damaging to the scaffold crotches or graft unions of young trees. Vigorous trees will heal over, but with heavy, prolonged infestations, scaffolds may break with wind or a heavy crop.

Solutions

Monitor young trees in spring and summer for frass and gum pockets. If larvae are found, spray tree trunks with applications of carbaryl two or three times during the growing season at 6-week intervals starting in mid-April. Use rates for trunk application. Spray from 1 foot above the scaffold crotch to 1 foot below. Whitewashing with a white interior nonenamel latex paint, diluted with an equal amount of water can be added for sunburn protection. Trees should not require protection after they are 5 years old.

American plum borer adult
American plum borer adult
Heavy infestations cause scaffolds to break
Heavy infestations cause scaffolds to break
Reddish orange frass
Reddish orange frass

Statewide IPM Program, Agriculture and Natural Resources, University of California
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Agriculture and Natural Resources, University of California

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