Q. Concerning my peach tree, it looks like the peach tree
borer is my most significant pest. Being that the Bt pesticide spray is a great
organic preventative and killer of the borer, and I already have it and use it
in my vegetable garden, shall I just spray the peach tree once a week as a
preventative? If I do, how long do I keep this up until the threat is over? Are
there any other insects to worry about such as aphids?
borer is my most significant pest. Being that the Bt pesticide spray is a great
organic preventative and killer of the borer, and I already have it and use it
in my vegetable garden, shall I just spray the peach tree once a week as a
preventative? If I do, how long do I keep this up until the threat is over? Are
there any other insects to worry about such as aphids?
A. There are two different borers which we must be
careful not to confuse. Control is entirely different between these two borers.
The borer you refer to damages the trunk and limbs of many trees including
fruit trees as well as ornamentals. This borer is very difficult to control
with pesticides.
careful not to confuse. Control is entirely different between these two borers.
The borer you refer to damages the trunk and limbs of many trees including
fruit trees as well as ornamentals. This borer is very difficult to control
with pesticides.
.jpg) |
| Flatheaded borer (probably either Pacific flatheaded borer or Flatheaded apple tree borer) that causes limb dieback |
Bt, an
organic spray made of a bacterium, will not kill these deadly borers which we
see as damage and dieback of limbs and entire trees. Bt sprays will, however,
kill a borer which causes wormy peaches, nectarines and apricots. This borer is
called the peach twig borer.
organic spray made of a bacterium, will not kill these deadly borers which we
see as damage and dieback of limbs and entire trees. Bt sprays will, however,
kill a borer which causes wormy peaches, nectarines and apricots. This borer is
called the peach twig borer.
Peach
twig borer kills the soft, succulent growth of peaches and nectarines at the
beginning of the growing season. We should start seeing this damage right now.
Its lifecycle is very short and so the population of this pest builds very
quickly to enormous numbers in a matter of a few months.
twig borer kills the soft, succulent growth of peaches and nectarines at the
beginning of the growing season. We should start seeing this damage right now.
Its lifecycle is very short and so the population of this pest builds very
quickly to enormous numbers in a matter of a few months.
 |
| Peach twig borer larva or immature form (striped) in the flesh of peach in upper right hand corner of the picture causes wormy peaches, nectarines, apricots, almonds |
As
peach, nectarine and apricot fruit matures and gets close to harvest, the
attacks from this pest switch from soft, succulent growth to soft succulent
fruit. These new attacks result in wormy peaches, nectarines and apricots.
Instead of shoots which dieback, the fruit becomes infested instead.
peach, nectarine and apricot fruit matures and gets close to harvest, the
attacks from this pest switch from soft, succulent growth to soft succulent
fruit. These new attacks result in wormy peaches, nectarines and apricots.
Instead of shoots which dieback, the fruit becomes infested instead.
The
trick is to get this pest under control as early in the season as possible to
prevent this pest’s population from exploding in numbers. We use sprays such as
Bt or Spinosad early in the season, starting now, to help keep these
populations small and under control.
trick is to get this pest under control as early in the season as possible to
prevent this pest’s population from exploding in numbers. We use sprays such as
Bt or Spinosad early in the season, starting now, to help keep these
populations small and under control.
I
usually apply one of these chemicals when I start to see a few new shoots of
peach and nectarine begin to die back. We call this flagging. We also use
special traps which catch and monitor this insect when it is hatching and
flying. You will see pictures of this on my blog.
usually apply one of these chemicals when I start to see a few new shoots of
peach and nectarine begin to die back. We call this flagging. We also use
special traps which catch and monitor this insect when it is hatching and
flying. You will see pictures of this on my blog.
 |
| Flagging from peach twig borer |
This
flagging is one indicator that you need to get out there and start spraying to
knock their numbers down and protect the fruit.
flagging is one indicator that you need to get out there and start spraying to
knock their numbers down and protect the fruit.
Unfortunately
there is not much that you can do to prevent the more damaging borer, a beetle
in its mature form, from laying its eggs on the upper surfaces of sunburned
branches. These insect eggs hatch and the larvae penetrate the tree through its
bark causing extreme damage to the limbs by tunneling just under their surface.
there is not much that you can do to prevent the more damaging borer, a beetle
in its mature form, from laying its eggs on the upper surfaces of sunburned
branches. These insect eggs hatch and the larvae penetrate the tree through its
bark causing extreme damage to the limbs by tunneling just under their surface.
The
peach twig borer adult on the other hand is a moth and its immature form is
also a larva but resembling what we might call a “worm” in appearance. The BT
sprays do not work on insects which are in the beetle family, only those whose
adults are moths.
peach twig borer adult on the other hand is a moth and its immature form is
also a larva but resembling what we might call a “worm” in appearance. The BT
sprays do not work on insects which are in the beetle family, only those whose
adults are moths.
Aphids
are not a big problem on peach like they can be on plums and plum relatives
like pluots. Aphids like cool weather and begin to disappear when it gets hot.
Their damage is usually cupped or distorted leaves which are frequently sticky
due to feeding by the aphids.
are not a big problem on peach like they can be on plums and plum relatives
like pluots. Aphids like cool weather and begin to disappear when it gets hot.
Their damage is usually cupped or distorted leaves which are frequently sticky
due to feeding by the aphids.
Because
the aphid season is short in our climate, they are usually not worth
controlling unless we have a prolonged cool spring.
the aphid season is short in our climate, they are usually not worth
controlling unless we have a prolonged cool spring.