Everything You Really Need to Know to Organically Control Birch Leaf Miner
Birch leaf miner is a particularly noxious pest of
birch trees and more importantly has spawned some even more noxious
it is important to keep your birch
trees healthy and actively growing.
This means feeding them with
compost (a quarter inch spread under the leaf canopy every spring or
fall) and making sure they don’t suffer drought damage.
So feed and
water are important to reduce the stress on this plant (as it is with
Birch tree leaves
Understand that a tree under stress will be more
attractive to pests. So the most important, least-costly and
most-effective first step is to feed and water.
Also understand that the birch leaf miner will not usually kill a
healthy tree even if it totally defoliates it.
It helps to understand the life cycle of this insect
The life cycle is important because it is an interesting and very
protective one. The pest
is a species of sawfly that overwinters in the ground as a pupa. The
adult fly hatches in the spring and immediately flies to the emerging
leaves, makes a slit in a leaf and lays the eggs. The adults then die
after a very brief lifespan.
The egg hatches and an immature worm or birch leaf miner starts eating
away between the layers of the leaf
where it is
protected from predators and our typical spray methods of control. When
it is ready to develop further, the miner drops to the ground and
burrows into the soil and makes a pupa. There can be several
generations of birch leaf miner each year with the last one staying in
the ground to overwinter and start the process again.
So how can we control this pest?
A contact spray
A spray such as soap will kill the adult sawfly but your
timing has to be perfect to get it - just as the leaves are unfolding.
The difficulty with these sprays is that birch trees can be quite tall
and getting a complete coverage involves spraying almost everything
within a half mile with the spray drift.
A contact spray will not
penetrate the leaf so the miner (larval form) is quite happily eating
sprays will not penetrate the ground to kill off the pupa.
Horticultural oil has been shown to be effective
against birch leaf miner. A spray as soon as the leaves start unfurling
and weekly until June will provide relief on smaller trees. Hort oil
will stay on the leaves and will have some residual action. Repeated
spraying are necessary as timing the hatch is critical.
Pricing and shipping options are here
This oil apparently acts as a deterrent to birch leaf miner so
this should be considered.
Pricing and shippimg options are here
These are the good guys. And the same
species that are used against lawn grubs are listed for the control of
the burrowing miner and larva. Apply as
per the instructions on the label and make doubly sure you water these
small creatures into the soil after you apply them.
This is a new form of insecticide and you might
want to investigate this chemical for control. It is being used in IPM
programs now. The jury is out on its effectiveness or ultimate
Check out pricing and delivery here
Rotenone is registered for use with sawflies but the
problem with Rotenone is that it is very short-lived (24 hours) and you
have to ensure the fly is flying or around before you can kill it. You
have to get the adult form of the birch leaf miner with this material
to be effective. Again, this is a very potent botanic insecticide and
full breathing masks should be worn if dusting or spraying with this
Click Here For Gardening For Beginner Gardening ebook
Cygon 2E is Not Recommended
This the chemical of choice and most often sold but this is one
of the most toxic chemicals used in the agriculture industry.
not recommend this in any shape or form.
The interesting factoid about
this chemical is that it has probably killed more birches than the
miner. You see, if you apply this using the label directions and paint
it on the trunk for two years in a row (or more) then you may wind up
killing the cells right under the bark and the tree will die. The birch
leaf miner gets the blame but the Cygon did the deed.
Never, ever spray
Cygon with a sprayer – this is acutely dangerous material.
Doug's Best Organic Option
Use predator nematodes to get basic control. You'll likely have some problems but not at a level of tree destruction.
If the problem becomes worse, apply more nematodes and spray with the horticultural oil or neem at the appropriate time
Got a comment? Click here for my forums and Q&A on my other website