Q: I have a
33-year-old birch tree that I have treated for birch leafminer for many
years using a Ross Root Feeder and Systemic Insecticide Root Feeder
cartridges. The product contains 2 percent Di-Syston. I cannot seem to
find the cartridges anymore. Are there other products that I can use?
A:
Di-Syston (disulfoton), the active ingredient in Ross Systemic Root
Feeder cartridges, is no longer available for home use. The
Environmental Protection Agency continues to review pesticides under the
Food Quality Protection Act of 1996, using stricter limits for human
exposure to these products. As a result, a number of pesticides are no
longer sold to home gardeners. They may still be available to licensed
pesticide applicators for commercial use, but often they cannot be
applied to residential properties.
Fortunately, there
are other products that control birch leafminers effectively and safely.
One that is particularly easy for home gardeners to apply is Bayer
Advanced Tree & Shrub Insect Control. It contains the systemic
insecticide imidacloprid as the active ingredient.
One application in
late winter will provide season-long control of birch leafminer, bronze
birch borer and other pests. The product is mixed with water and applied
with a bucket or watering can to the tree's root system. Like the root
feeding system you have been using, there is no spraying involved.
River Birch is less prone to insect problems
You have to measure
the circumference of the trunk of the tree, or add up the circumferences
of all the trunks of a multitrunked specimen, to determine how much of
the concentrated product to use. You mix it with 1 gallon of water (2
gallons for trees with a circumference greater than 50 inches), and then
apply the mixture slowly and evenly around the base. Stay close to the
trunk, but try to get the product on the ground where it can be absorbed
by the roots. Refill the bucket or watering can with plain water and go
over the area where you applied the mixture to water it into the root
zone.
It does take time for
the product to be absorbed, anywhere from a week to three months,
depending on the size and health of the tree. Bayer Advanced Tree &
Shrub Insect Control can be applied any time the ground is not frozen or
waterlogged. It is also important that there is adequate soil moisture
prior to application. If we have not had rain, be sure to water the area
under the tree the day before you make the application.
Adult leafminers are
active and laying eggs as birch trees leaf out in the spring (May). A
second generation hatches out in mid-to-late June. You want to be sure
to apply the Bayer product early enough, so that tree has time to take
it up and transport it through the branches before the adults become
active. It will not be effective if applied after you see leafminer
activity.
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