Asian Ambrosia Beetle

Question:
My Japanese maple tree started to leaf out this spring, 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?

Answer:
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 ambrosian beetle.  It will attack seemingly healthy trees.  We have had numerous reports of strong, healthy trees which either began to leaf out and die, 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 tunnel in the tree.  This “sawdust” can wash off or blwo 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 order.  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 befenthrin.  Some common tradenames include: Hi-Yield 38 Plus, Turf, Termite and Ornamental insect Control, Eight labeled for boring insects.  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 redbuds and dogwoods in your landscape, you may want to take the precautionary approach and spray the tree trunks now.  Follow label directions as to recommended frequency of the 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 plants in question are often some of the more pricey items in the landscape, Japanese maples, is another call to action.  If you have any questions please feel free to give us a call at (870) 935-0357 or email us at larryvickers@sartinservices.net.