Q. Several years
back my father and I planted two Raywood ash trees in each of our yards. Now
both of trees have longitudinal gashes along the stems that kill many of the
smaller branches. Last year I found the
same problem on one of my rose bushes. Per the recommendation of the nursery I
sprayed a systemic containing imidacloprid and clothianidin on the trees.
My picture showing cicada damage to small stems on Acacia.
A. This sounds
like egg laying damage by the Apache cicada; those high-pitched insects you
hear buzzing in about July. The insecticide you are spraying will not correct this
problem so stop using it.
This female cicada is not laying eggs…yet..
Apache
cicadas make that buzzing noise so they can mate. Once they have mated, the
female lays eggs in a slit she creates on the branches. If these slits cause
enough damage, the twig dies. The eggs then hatch, and the insect drops to the
ground where they burrow into the soil and feed on plant roots. Lots of
different trees are favorites, your ash trees (sounds like the roses, too) being among them.
 |
| Cicada empty skin or exoskeleton left behind on anything they can find when they emerge from the ground. |
Spraying
the tree with an insecticide, or drenching the soil with one, is not a good
idea. I think your best bet is to give your trees as much chance to heal
themselves, after the damage is done, as possible. Their best chance of healing
from this type of damage is the presence of fertilizer in the soil and adequate
water during the heat. Of course, scaring these insects off to other trees
during mating time would help.
Make
sure these trees are fertilized in the spring and bump up the amount of water
applied when you start hearing the buzzing noise. You might even try watering
every other day during this period to help the tree recover from cicada egg
laying damage.