Q. Several years ago I purchased a Raywood Ash and I have
been pruning off infected branches at the beginning of each season. Last week someone
had a nursery suggested I apply a systemic containing imidacloprid and
clothianidin as active ingredients to try to get some control. Do you know what
the problem is?
been pruning off infected branches at the beginning of each season. Last week someone
had a nursery suggested I apply a systemic containing imidacloprid and
clothianidin as active ingredients to try to get some control. Do you know what
the problem is?
 |
| Cicada damage to small limbs on sweet acacia |
A. The problem you are seeing is most likely cicada
damage from egg laying that is now healing. The female cuts a slit parallel along the top of the stem
parallel to the branch with her ovipositor (egg laying machinery). The female
deposits her flattened oval eggs, about an eighth of an inch long, stacked up
against each other along that slit in a nice row.
damage from egg laying that is now healing. The female cuts a slit parallel along the top of the stem
parallel to the branch with her ovipositor (egg laying machinery). The female
deposits her flattened oval eggs, about an eighth of an inch long, stacked up
against each other along that slit in a nice row.
 |
| Cicada (probably apache cicada) on the limb of a sweet acacia in late June |
If you
look at the old twig damage closely, the slit looks like tiny teeth on a saw
and that slit is healing nicely. When the eggs hatch a few weeks later, the
babies fall to the ground and take into the soil where they feed on tree roots.
look at the old twig damage closely, the slit looks like tiny teeth on a saw
and that slit is healing nicely. When the eggs hatch a few weeks later, the
babies fall to the ground and take into the soil where they feed on tree roots.
The
insecticide applied as a soil drench might work because it is systemic. Another
option is to apply a soil insecticide drench intended for killing grubs in the
soil or eliminating the cicadas on the tree as you see them and before they
have a chance to cut a slit and lay their eggs.
insecticide applied as a soil drench might work because it is systemic. Another
option is to apply a soil insecticide drench intended for killing grubs in the
soil or eliminating the cicadas on the tree as you see them and before they
have a chance to cut a slit and lay their eggs.
Continue
to cut off the branches if you want if they are unsightly to you, but the tree
will heal fast if it is kept healthy.
to cut off the branches if you want if they are unsightly to you, but the tree
will heal fast if it is kept healthy.