Q. We have lots of
aphids in our good-sized oak trees that are dropping sap on our cars and the
sidewalk. Short of cutting the trees down, do you have any suggestions on how
to get rid of the aphids?
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| Not from the reader but aphid sticky exudate on oak. |
A. Blame their high population number
s this year on our
wet and humid spring weather. The fastest and probably cheapest way to get rid
of them is to drench the soil beneath the tree with a systemic insecticide
diluted in a bucket of water. This dilution will help you spread it more evenly
everywhere under the tree.
 |
| aphids on pomegranate |
The
pesticide I’m telling you to use has the active ingredient imidacloprid
in it. This insecticide is systemic so when you pour this around the base of
the tree, diluted in water, the roots will take it up and transport it to the
leaves. Since the aphids are sucking juices out of the leaves, they ingest this
toxin and die.
pesticide I’m telling you to use has the active ingredient imidacloprid
in it. This insecticide is systemic so when you pour this around the base of
the tree, diluted in water, the roots will take it up and transport it to the
leaves. Since the aphids are sucking juices out of the leaves, they ingest this
toxin and die.
 |
| Leaf curl on plum from early feeding and leaf expansion |
There
are several trade names of this pesticide that contain imidacloprid. The most
popular with homeowners is the Bayer product with the trade name “Tree and
Shrub Insect Control”. Any product that you use must contain imidacloprid
in the ingredients. The easiest and probably safest way to apply it is a “soil
drench” but it can be sprayed on the leaves as well.
are several trade names of this pesticide that contain imidacloprid. The most
popular with homeowners is the Bayer product with the trade name “Tree and
Shrub Insect Control”. Any product that you use must contain imidacloprid
in the ingredients. The easiest and probably safest way to apply it is a “soil
drench” but it can be sprayed on the leaves as well.
 |
| One of the many products that contain imidacloprid. It is now the most used insecticide in the world. |
The
label will tell you how much of this pesticide is applied to one tree. Follow
the directions on the label for a soil drench application. When you are
finished with the application, rinse the bucket three times with fresh water
and apply these “rinsates” under the tree as well. Wear unlined plastic gloves
and eye protection when mixing and applying this product and rinse, or dispose
of them, afterwards.
label will tell you how much of this pesticide is applied to one tree. Follow
the directions on the label for a soil drench application. When you are
finished with the application, rinse the bucket three times with fresh water
and apply these “rinsates” under the tree as well. Wear unlined plastic gloves
and eye protection when mixing and applying this product and rinse, or dispose
of them, afterwards.
 |
| Chitalpa black aphid |
Consider
spraying these trees during the wintertime, from top to bottom, with a dormant
oil. Apply an extra dose to the base of the tree where aphids might be hiding.
Dormant oil sprays applied during the winter are very effective in reducing the
populations of aphids, scale insects and spider mites for the next growing
season.
spraying these trees during the wintertime, from top to bottom, with a dormant
oil. Apply an extra dose to the base of the tree where aphids might be hiding.
Dormant oil sprays applied during the winter are very effective in reducing the
populations of aphids, scale insects and spider mites for the next growing
season.
 |
| Entrance to an ant colony on the orchard floor. |
Ants
love aphids. They “milk” ants of this sugary sap for their own use. If you look
at the tree trunks carefully, you will see a steady stream of ants going up and
down the trunk. They are also part of the aphid problem and should be
controlled. Follow the stream of ants back to the opening of the underground
nest. Sprinkle 10 or 15 “crystals” of ant bait directly at the opening of the
nest. I use a product called “Amdro”. The nest will be empty the next day.
love aphids. They “milk” ants of this sugary sap for their own use. If you look
at the tree trunks carefully, you will see a steady stream of ants going up and
down the trunk. They are also part of the aphid problem and should be
controlled. Follow the stream of ants back to the opening of the underground
nest. Sprinkle 10 or 15 “crystals” of ant bait directly at the opening of the
nest. I use a product called “Amdro”. The nest will be empty the next day.