American PLum Borer
Beginner
This pest affects:
 |
 |
 |
 |
 |
Scientific Name
Euzophera semifuneralis
Identification
Eggs
- Tiny, oval and covered with a network of triangular facets
- Dirty white when first laid but darken to pink, then deep red, as they mature
- Laid singly or in small masses in or near the gummosis on trunk wounds
- Greyish-green to greyish-purple
- Head capsule, prothoracic shield, and anal plate are yellow to brown
- Prothoracic shield has dark markings on either side
- 1st instar larva 0.25 mm long; last instar 18-25 mm long
Pupae
- Found among frass under the bark, within silken cocoons
- 11-12 mm long
- Tan to dark brown, with black eyes
- Empty pupal skin is found inside the cocoon
- Emerged pupal skins of the plum borer do not extrude from the cocoon or from the bark
Adults
- Wingspread 17-28 mm
- Forewing narrow and somewhat triangular; generally reddish brown, marked by wavy black and brown vertical bands about 2/3 of the distance from its base
- Hind wing broad and fringed on the trailing edge: pale brownish grey with a darkened margin at the base of the fringe. Some veins of the hind wing may be darker than the wing
Damage
- Often found in close association with the Lesser Peach Tree Borer in stone fruits
- Larvae feed on cambium
- Larvae enger through openings created by mechanical damage, diseases, sunscald, winter injury, etc.
- May be 40 or more larvae in a single tree; number of larvae per tree is correlated with the severity of bark damage
- Larvae bore into the tree leaving gum pockets and reddish orange frass loosely cemented together by a small amount of sap
- May eventually girdle the trunk or scaffolds; 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
- Damage may go unnoticed because the outer bark usually remains intact. In heavily infested trees, seemingly live bark can be pulled away to reveal many of these cocoons
|
In sour cherry, girdling of trunk and lower scaffold limbs within 1.2 m of the ground where the clamps from the trunk shakers have caused wounds for entry . Sour cherry trees appear to be more susceptible to borer damage in years three to five while mature trees can withstand higher levels of infestation. |
| |
Common in black knots in sour cherries and plums. |
Often Confused With
Peachtree borer and lesser peachtree borer
- larvae creamy white with a yellowish-brown to dark brown head capsule. In addition, one row of crochets at the tips of the abdominal prolegs; no long primary setae
- Larval feeding produces frass mixed throughout large amounts of gum
- Pupa of the LPTB are similar in size, but the cocoons are a dark brown color with the frass forming an integral part of it
- Pupal skins protrude from exit holes on the outside of the bark)
- Fewer larvae per wound than APB
- Feed both horizontally and vertically rather than just horizontally
Shothole borer - numerous exit and entrance holes obvious on the outside of infested limbs give a shothole effect; below the bark, slender mines, usually at right angles to the maternal gallery, occasionally crisscrossing over one another between the bark and the sapwood; exit burrows from the pupal cells to the outside.
Period of Activity
There are two moth flights per year. Most larvae pupate within the hibernacula as soon as the cherry buds begin to open, and first adult emergence occurs by the white bud stage about 2 weeks later. Peak adult emergence of the first generation occurs just after full bloom. The second flight peaks near the end of July. Adults are active at night and seldom seen.
Scouting Notes
APB prefers tart cherry, plum, and sweet cherry, but is an occasional pest of pear, peach, nectarine and apple. Mechanically harvested sour cherry trees tend to have more APB larvae than peaches or plums because of the severity of the damage done by shakers.
Heavy infections of black knot growth in plum orchards are extremely attractive feeding sites for the larvae.
Most APB larvae are found within four feet of the ground, although in trees infected with black knot or Cytospora canker they may be found in cankers higher in the tree.
Peak emergence and egg laying coincides with the mechanical harvesting of cherries when there is an abundance of fresh cracks and wounds suitable for oviposition.
Sample in the fall or early spring for larvae. Use a hammer and a long screwdriver to pry back the bark where damage is apparent. Remove bark until live cambium is reached and look for larvae feeding along the edge of the live cambium or cocoons attached to the inside of the bark. Use forceps to look under fresh frass.
Threshold
There is no experimentally determined action threshold for its control with insecticides. However, because of the likelihood of severe damage in the long run, few should be tolerated.
Advanced
This pest affects:
|
|
|
|
|
Scientific Name
Euzophera semifuneralis
Identification
Eggs
- Tiny, oval and covered with a network of triangular facets
- Dirty white when first laid but darken to pink, then deep red, as they mature
- Laid singly or in small masses in or near the gummosis caused by bark wounds
- Greyish-green to greyish-purple
- Head capsule, prothoracic shield, and anal plate are yellow to brown
- Prothoracic shield has dark markings on either side
- 1st instar larva 0.25 mm long; last instar 18-25 mm long
Pupae
- Found among frass under the bark, within silken cocoons
- 11-12 mm long
- Tan to dark brown, with black eyes
- Pupation takes about 4 weeks in the spring
- Empty pupal skin is found inside the cocoon
- Emerged pupal skins of the plum borer do not extrude from the cocoon or from the bark
Adults
- Wingspread ranges 17-28 mm
- Forewing narrow and somewhat triangular; generally reddish brown, marked by wavy black and brown vertical bands about 2/3 of the distance from its base
- Hind wing broad and fringed on the trailing edge: pale brownish grey with a darkened margin at the base of the fringe. Some veins of the hind wing may be darker than the wing
Damage
- Often found in close association with the Lesser Peach Tree Borer in stone fruits
- Larvae feed on cambium
- Enter through openings created by mechanical damage, diseases, sunscald, winter injury, etc.
- May be 40 or more larvae in a single tree; number of larvae per tree is correlated with the severity of bark damage
- Larvae bore into the tree leaving gum pockets and reddish orange frass loosely cemented together by a small amount of sap
- May eventually girdle the trunk or scaffolds; 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
- Damage may go unnoticed because the outer bark usually remains intact. In heavily infested trees, seemingly live bark can be pulled away to reveal many of these cocoons
| |
In tart cherry, girdling of trunk and lower scaffold limbs within 1.2 m of the ground where the clamps from the trunk shakers have caused wounds for entry . Tart cherry trees appear to be more susceptible to borer damage in years three to five while mature trees can withstand higher levels of infestation. |
|
|
Common in black knots in tart cherries and plums. |
Often Confused With
Peachtree borer and lesser peachtree borer
- larvae creamy white with a yellowish-brown to dark brown head capsule. In addition, one row of crochets at the tips of the abdominal prolegs; no long primary setae
- Larval feeding produces frass mixed throughout large amounts of gum
- Pupa of the LPTB are similar in size, but the cocoons are a dark brown color with the frass forming an integral part of it
- Pupal skins protrude from exit holes on the outside of the bark)
- Fewer larvae per wound than APB
- Feed both horizontally and vertically rather than just horizontally
Shothole borer - numerous exit and entrance holes obvious on the outside of infested limbs give a shothole effect; below the bark, slender mines, usually at right angles to the maternal gallery, occasionally crisscrossing over one another between the bark and the sapwood; exit burrows from the pupal cells to the outside.
Biology
American plum borer has an extensive range of hosts including at least 15 families of fruit, nut, ornamental, and forest trees, and a few woody annuals.
Because 3rd through 7th instar larvae can overwinter and must complete development in the spring, pupae of the overwintering generation may be found from early April to early June. This results in an extended emergence of first flight adults. The female is attracted to gum exuded from wounds in the bark of stone fruit trees. It lays 20-50 eggs in a couple of days on or near this gum. First generation eggs hatch in late May or early June and larval development is completed 4-5 weeks later. Second generation larvae begin to hatch in late July or early August and develop until sometime in mid-October when they enter diapause. After hatching, larvae move into frass from earlier larval feeding or to the edge of the cambium. They feed along this edge throughout their development.
Period of Activity
There are two moth flights per year. Most larvae pupate within the hibernacula as soon as the cherry buds begin to open, and first adult emergence occurs by the white bud stage about 2 weeks later. Peak adult emergence of the first generation occurs just after full bloom. The second flight peaks near the end of July. Adults are active at night and seldom seen.
Scouting Notes
APB prefers tart cherry, plum, and sweet cherry, but is an occasional pest of pear, peach, nectarine and apple. Mechanically harvested sour cherry trees tend to have more APB larvae than peaches or plums because of the severity of the damage done by shakers.
Heavy infections of black knot growth in plum orchards are extremely attractive feeding sites for the larvae.
Most APB larvae are found within four feet of the ground, although in trees infected with black knot or perennial canker they may be found in cankers higher in the tree.
Peak emergence and egg laying coincide with the mechanical harvesting of cherries when there is an abundance of fresh cracks and wounds suitable for oviposition.
Sample in the fall or early spring for larvae. Use a hammer and a long screwdriver to pry back the bark where damage is apparent. Remove bark until live cambium is reached and look for larvae feeding along the edge of the live cambium or cocoons attached to the inside of the bark. Use forceps to look under fresh frass.
Threshold
There is no experimentally determined action threshold for its control with insecticides. However, because of the likelihood of severe damage in the long run, few should be tolerated.
Management Notes
Try to minimize injury to trunks by shakers.
Paint white latex paint on trunks to reduce southwest injury and deter female moths from laying eggs.
Avoid solid mouse guards as they can increase winter injury and provide an excellent habit for borers to lay their eggs. Wire mesh mouse guards are a better option.
Natural enemies may play an important role in reducing APB larval populations. Birds, especially woodpeckers, feed on larvae throughout the year. A number of species of parasitic wasps, predatory insects, and spiders also feed on APB.
Insecticides applied for peachtree borer and lesser peachtree borer may help with American plum borer management.
Some information included above excerpted from;
