Unfortunately, you are not alone. While we have seen some signs of this
insect pest in the past, it seems to have hit us hard this spring. The
insect is called an Asian ambrosia beetle. This small beetle is a relatively
new pest and has numerous hosts it can attack, including maples—both
Japanese and Red Maples, redbuds, ornamental cherry, peach, plum, dogwood, styrax
and even azaleas. The pest was first detected on young peach trees in South Carolina in 1974.
Female beetles bore into the sapwood of stems and young thin-barked trees. The boring is not
what kills the tree—death is caused by fungal infection that is spread by the insects, as they
tunnel into the heartwood of the tree. Traditionally, boring type insects attack plants that
were weak or stressed, but that is not the case with the Asian ambrosia beetle. It will attack
seemingly healthy trees. We have had numerous reports of strong, healthy trees which either
began to leaf out and died, or simply didn’t leaf out at all. So far, most of the dead or
damaged trees we have seen include Japanese maples, red maples and redbuds. An easily
identifiable marker is the toothpick-like strands of sawdust that stick out along the trunk of
the tree. It is composed of the boring dust produced by the insect as she makes her tunnels in
the tree. This "sawdust" can wash off or blow off easily, and will leave behind small holes.
Once you see the sawdust tubes, the tree is often gone. Infested wood is discolored and has a
foul odor. Dead trees should not be left in the landscape—they should be cut down and destroyed.
Take precautions on nearby valuable young trees, by spraying the trunks of the trees with a
product containing permethrin or bifenthrin. Some common trade names include: Hi-Yield 38 Plus,
Turf, Termite and Ornamental insect Control, Eight insecticide and Talstar. Other products are
available. Check the label to make sure it is labeled for boring insects. Since the Asian
ambrosia beetle does not consume the wood it is tunneling through, systemic insecticides have
not proven effective for control.
Since this pest has not limited its attack to unhealthy trees, if you have valuable
Japanese maples or red maples, redbuds and dogwoods in the landscape, you may want to take
the precautionary approach and spray the tree trunks now. Follow label directions as to
recommended frequency of application, since products do vary. Our recommendation for next
season, would be to apply the product March 1, and then as recommended on the label until
the end of May. For this year, one or two applications applied to the trunk would be advisable
now, again, according to label directions. While we don’t want to cause widespread panic,
enough plants have been infested this spring, that we don’t want to ignore the issue. The
fact that the plants in question are often some of the more pricey items in the landscape -
i.e., Japanese maples - is another call to action. If you have questions, visit our website
at www.uaex.edu or call your local county extension agent.
(May) My Japanese maple tree started to leaf out this spring, and then just stopped. The leaves that
began to grow, shriveled and died, and nothing else has happened. I thought maybe it got hit by
a cold snap or something, and would recover, but there are no new leaves in sight. The tree is
three years old and has done well every year. I amended the soil well at planting, it is well
drained, and I have watered when dry. When I look at the tree, there is some unusual type of
growth coming out of the trunk—small straight tube-like growth, all around the trunk of the tree.
What is happening and is there anything I can do to save my tree?