Ambrosia Beetles are Now Out and Active Attacking Trees – from Stanton Gill, Extension Specialist, University of Maryland Extension
You are receiving this before Friday because of the immediateness of the pest. We have 15 alcohol baited Lindgren traps and 10,   95 % ethyl alcohol baited wood bolts in various parts of the state to monitor for ambrosia beetles. Participants are sending samples to the CMREC lab every 3 -4 days. On Monday afternoon (April 5, 2010)  I was using the dissecting microscope to examine the trap catches from several of the nursery sites. There are hundred of native bark beetles being pulled in by the4 alcohol traps at this time of year.  Two of the sites, one in Hartford County and one in Montgomery County had low number (1 – 2 ) of ambrosia beetles Xylosnadrus germanus. In addition,  I received in an electronic picture from a trapping site in upper Montgomery County. This person had shot a picture of a beetle they had caught in the trap at their site and they had placed in under a dissecting scope for the picture. It appears to be Xylosandrus crassiusculus. At this site they captured the beetle on April 3.. I have asked them to send in a sample to our lab at CMREC.
Finally,  last night at 8:30 p.m I received a call on my cell phone from a nursery owner who did not have one of our Lindgren alcohol baited traps at his nursery. He was out walking his nursery just before sunset and he noticed that the Styrax trees in his nursery had wet spots on the trunk. He found ambrosia beetles just starting to chew into he bark with a couple having wood and frass just starting around the holes. He was very agitated and immediately  applied an insecticide on  the beetles. I would have liked to see some specimen and I will visit the site to try to obtain samples this week.
The bottom line is ambrosia beetle adults are out and active attacking trees, at least in central Maryland. we have a sampling site in the Eastern shore and I have not received in any samples of ambrosia beetles fro the shore area. If they are active here in central Maryland, then I would think they would be active on the Eastern shore also.
Here is Why These Beetle are So Important:

In Maryland we have many species of native ambrosia beetles. These native species of ambrosia beetles have evolved overtime with the native species of plants.  We generally observe that these native ambrosia beetles usually only attack weakened trees. We do not generally worry about the native ambrosia beetles as major nursery or landscape pests.

There are two non-native invasive species of ambrosia beetles, Xylosandrus germanus and  Xylosandrus crassiusculus that are causing us concern in Maryland. Xylosandrus germanus was introduced from Japan into the United States back in 1932 and has spread through most of the northeast. Xylosandrus crassiusculus was reported in many southern states for years. It has been recorded in Maryland.

In 2006  through 2008 we suffered through extensive drought conditions which may have left some tree species weakened and susceptible to damage from non-native ambrosia beetles. The interesting thing is that trees that were under trickle irrigation in these drought years still were attacked by ambrosia beetles. It may be that the trickle irrigation systems are not supplying adequate amounts of water to keep the energy levels at a maximum and these trees are being weakened in a way not apparent to casual observation. In 2009 we had rain for most of the season, with a short drought of 4 weeks in July.  Other then this the season was plentiful in rainfall. Still, we saw a fair amount of ambrosia beetle damage. This needs further research to determine what triggers susceptibility to non-native ambrosia beetle attack.

Damage from the  ambrosia beetle, Xylosandrus germanus, reached new high levels in Maryland in 2008 and an even higher level in 2009.  We have recorded this beetle damaging honeylocust (Gledistia triacanthos), London plane tree, Zelkova, river birch, American holly (Ilex opaca), American beech, sweet bay magnolia (Magnolia virginiana), Chinese dogwood (Cornus kousa), Hybrid dogwoods (especially the Stellar series) , yellowwood, sugar maple, hybrid chestnuts, and Styrax.  In 2009 Xylosandrus crassiusculus was found damaging crepe myrtle, oriental persimmon, flowering plum, deciduous azalea, and red maple.

Control
The time to apply sprays to prevent females from drilling into the trees is NOW! In nursery the labeled material is bifenthrin sold under the name Onyx. In the landscape certified pest applicators can either use Onyx or permethrin, sold under several names including  Astro and Peremethrin E.C.


submitted by:

Sara Fern Fitzsimmons
Northern Appalachian Regional Science Coordinator
The American Chestnut Foundation®
The Pennsylvania State University
206 Forest Resources Lab
University Park, PA 16802

e-mail: sara@acf.org
phone (office): 814-863-7192
phone (cell): 814-404-6013
fax: 814-863-3600

http://chestnut.cas.psu.edu
http://www.acf.org
 http://www.patacf.org