Ash borer killing locust trees?

[Lightning Performance]

Seeing black locust trees dying from the top down or only on one side of the canopy from the ends inward. It looks like emerald ash bore death. Several properties where ash were removed by me last year have two that are looking like this is the problem. Need to get a limb and confirm it. Waiting on one to fall this month. I have removed several maple trees that were in a stand of dead ash and they died the next year after the ash was removed. Clearly killed by the same bug.

 

[MMG]

That is not good news

 

[kuhndog]

On Locust it's usually the Locust Leal Miner and it starts about now

 

[pdqdl]

Clearly killed by the same bug.

While top-down decline is a sign of the systemic vascular problems caused by borers, LOTS of other diseases will cause the same appearance. Borer holes are the best indicator of borers.

Most unlikely to be the same bug, even if it is borers causing the problem. Research says:

"Locust trees, which can refer to different species in the genera Robinia or Gleditsia, can be affected by various borer insects. Some of the common borers that have been known to infest locust trees include:​

1. Locust Borer (Megacyllene robiniae): This borer insect is specifically associated with black locust trees (Robinia pseudoacacia) and can cause significant damage to their stems and branches.
2. Honeylocust Borer (Euclea delphinii): This borer primarily targets honeylocust trees (Gleditsia triacanthos). It tunnels into the trunk and branches, causing structural damage and potentially leading to tree decline.
3. Powderpost Beetles (Lyctinae subfamily): While not specific to locust trees, powderpost beetles can infest various hardwoods, including some species of locust trees. They lay their eggs in cracks and crevices, and the larvae tunnel into the wood, causing damage.
4. Dogwood Borer (Synanthedon scitula): Although its primary host is the flowering dogwood (Cornus florida), this borer can also infest some species of locust trees.
5. Flatheaded Appletree Borer (Chrysobothris femorata): This borer targets various hardwood trees, including some species of locust. It can cause extensive damage to the phloem and cambium layers.
6. Pacific Flatheaded Borer (Chrysobothris mali): Another flatheaded borer that can infest locust trees, particularly if they are stressed or weakened.
7. Oak Borer (Enaphalodes rufulus): While its primary host is oak trees, this borer can also affect locust trees, especially when the trees are under stress."

 

[pdqdl]

Locust leaf miner will cause significant defoliation, but not tree death except that it weakens the tree and makes it more susceptible to other problems.

I'd suggest some additional investigations, binoculars will help.

• Look for borer exit holes, generally lower on the tree, well below branches that are dying.
• look for fungi fruiting bodies, discoloration, bark peeling, or other signs of root or trunk damage by fungi.
• look at adjacent vegetation for patterns of chemical kill.
• examine the falling leaves for evidence of the leaf miners: They hatch from the eggs and burrow into the leaf tissue, where they start feeding on the plant's cells. As they feed, they create serpentine mines or blotches within the leaf, leaving visible trails.
  • These trails should be visible in the fallen leaves that die. After completing their feeding and growth phase, the larvae exit the leaf and pupate on the ground or within the leaf litter. During the pupal stage, the larvae transform into adults inside protective pupal cases.
  • Look for adult insect: Once the transformation is complete, the adult Locust Leaf Miner emerges from the pupal case. The adults are small, metallic-colored flies with elongated bodies. They have transparent wings and distinctive black markings on their bodies. The adults feed on nectar and continue the life cycle by mating and laying eggs on the leaves of the black locust tree.

 

[Lightning Performance]

Locust leaf miner will cause significant defoliation, but not tree death except that it weakens the tree and makes it more susceptible to other problems.

I'd suggest some additional investigations, binoculars will help.

• Look for borer exit holes, generally lower on the tree, well below branches that are dying.
• look for fungi fruiting bodies, discoloration, bark peeling, or other signs of root or trunk damage by fungi.
• look at adjacent vegetation for patterns of chemical kill.
• examine the falling leaves for evidence of the leaf miners: They hatch from the eggs and burrow into the leaf tissue, where they start feeding on the plant's cells. As they feed, they create serpentine mines or blotches within the leaf, leaving visible trails.
  • These trails should be visible in the fallen leaves that die. After completing their feeding and growth phase, the larvae exit the leaf and pupate on the ground or within the leaf litter. During the pupal stage, the larvae transform into adults inside protective pupal cases.
  • Look for adult insect: Once the transformation is complete, the adult Locust Leaf Miner emerges from the pupal case. The adults are small, metallic-colored flies with elongated bodies. They have transparent wings and distinctive black markings on their bodies. The adults feed on nectar and continue the life cycle by mating and laying eggs on the leaves of the black locust tree.

That last one is another nasty little bug with multiple cycles in a year.

 

[pdqdl]

That last one is another nasty little bug with multiple cycles in a year.

I've never seen them in this area, and was unaware of the problem until previously mentioned. Credit where credit is due:

On Locust it's usually the Locust Leal Miner and it starts about now

Not mentioned in my previous posts: the leafminer pupae stage occurs on the ground level. If you determine that leaf miners are your problem, you can probably break the cycle by doing extensive leaf-litter control. Keep 'em raked up, possibly adding some insecticide effective on the emerging adults.

That's just a thought; I've done no research on that suggestion, and have no experience with the insect.

 

[Lightning Performance]

I've never seen them in this area, and was unaware of the problem until previously mentioned. Credit where credit is due:



Not mentioned in my previous posts: the leafminer pupae stage occurs on the ground level. If you determine that leaf miners are your problem, you can probably break the cycle by doing extensive leaf-litter control. Keep 'em raked up, possibly adding some insecticide effective on the emerging adults.

That's just a thought; I've done no research on that suggestion, and have no experience with the insect.

I have experience with insects in leaves. Burn them where they lay or in a barrel right there. We do this with wood at the wood lot. The story ends there most times. The char is free fertilizer.

 

[Lightning Performance]

My black walnuts are all healthy so I should start selling them this winter. Got maybe fifty here to get rid of naturally occurring trees from grey squirrels.