OVERTON, Texas, May 11, 2004 (ENS):
The Asian ambrosia beetle is now appearing in devastating
numbers and is wreaking havoc among the Southern U.S.
ornamental tree growing industry this year, researchers
A research team investigating methods of controlling
the pests warns that a good part of the $225 million
East Texas nursery industry is at risk from the invasive
beetle, which also threatens pecan orchards and species
such as redbud, ornamental pears and red oaks.
The tiny beetle is known to attack more than 100 species
of trees, but seems to favor and do more damage to juvenile
trees such as those found in tree nurseries.
Less than three millimeters long, the miniscule beetles
can kill a tree in a few weeks.
"We have some growers who have lost whole species
of trees this year," said Dr. Scott Ludwig, a Texas
Cooperative Extension integrated pest management specialist.
"I heard very little about the beetle from the
growers the first two years I was here," said Ludwig,
who has been working in East Texas for three years.
No one knows why the insect made such an impact this
year, but Ludwig said it is suspected that mild winters
have played a big role.
The adult beetles overwinter in leaf litter, and warmer
winters could result in more insects surviving to emerge
in the spring.
"But that is just conjecture at this point,"
Ludwig said. "We do not know for sure."
Ambrosia beetles are so named because they cultivate
the ambrosia fungus inside the tree.
The pest does so for the same reason that a number
of ant species farm fungi, to produce food. The fungus
plugs up the tree's vascular system, the collection
of tiny vessels that transports water and nutrients
to the plant cells.
"It is really the ambrosia fungus that kills the
tree, not the beetle," said Ludwig, who has launched
an two-fold emergency program to deal with the threat.
One program, funded by the U.S. Department of Agriculture,
is the testing of a new preventative trunk spray at
two nurseries. The other is a trapping survey to find
out just how deeply the Asian ambrosia beetle is entrenched
in East Texas.
Ludwig designed the survey to monitor when the adults
emerge from the trees and determine what other species
of ambrosia beetle are present.
Once a tree is infested, no chemical controls will
save it. A tree may be infested by a single beetle or
For juvenile trees, up to three years old, the infestation
most often proves fatal.
Mature trees are more likely to survive the infestation
but may serve as staging base for the beetle to attack
nearby younger trees.
For this reason, the general control strategy is to
cut down and destroy any infested trees immediately.
"The quandary comes when a favorite mature tree
is infested," he said. "No one wants to cut
down and burn an otherwise healthy tree, but not doing
so could endanger new trees in the area."
Copyright Environment News Service (ENS) 2004. All Rights