Native Ambrosia Beetles (Platypus spp.) will attack mostly pines, and the exotic
Asian Ambrosia Beetles (Xylosandrus crassiusculus) will attack hardwoods and
fruit trees. They chew the sapwood to create winding tunnels called
galleries. The Ambrosia Beetle uses the galleries to grow a fungus as
their food. This fungus, called the Ambrosia fungus gives the beetle its name.
The Ambrosia Beetle transports the fungal spores with it from tree to
tree. The ambrosia fungus is not a pathogen to the tree, but the galleries
are the cause of tree decline and possible death. Only stressed or weakened
trees are targeted by the Native Ambrosia Beetle. The exotic, invasive
Asian Ambrosia Beetle will attack healthy as well as stressed trees.
SYMPTOMS:
Look for sawdust at the base of the tree. Fragile spines
of sawdust (frass) may also be seen on branches and stem of the tree.
Foliage of the infested tree will begin to wilt.
PHOTOS:
A: Adult
Asian Ambrosia Beetle, B: Fragile spines of frass and sawdust
from Asian Ambrosia Beetle. C: Ambrosia beetle leaves sawdust
at tree base Photo
A taken by Steve Passoa, USDA APHIS PPQ, www.forestryimages.org. Photo B taken from
aggie-horticulture.tamu.edu. Photo
C taken by Ronald F. Billings, Texas Forest Service,
www.forestryimages.org.
Arborjet is developing an
insecticide for control of native and Asian Ambrosia Beetle infestation.
Our research shows this new insecticide to be highly effective against
scolytids. The Scolytidae also includes Ips and Dendroctonus spp. commonly
called pine bark
beetles. This new formulation is projected to be available for spring
of 2008.
Generally, the best seasons for Micro-infusion
TM are fall and
spring. Uptake occurs when trees are transpiring. The environmental conditions
that favor uptake are moderate temperatures, adequate soil moisture, and high
humidity. Soil temperature should be above 40 degrees for
micro-infusion™. Tree health will influence uptake time. Generally,
hot weather or dry soil conditions will result in a reduced rate of
uptake. If treating trees in the summer, micro-infuse in the morning for
the quickest uptake. A dying tree is a poor candidate for treatment. It is
the responsibility of the arborist or tree custodian to assess tree health and
its potential for recovery before undertaking treatment.
A tree with an Ambrosia beetle infestation is likely to be moisture
stressed. If possible, water the
tree prior to treatment to improve the uptake and diffusion in the tree.
Depending on environmental
conditions and tree health, it will take from 30 minutes to one hour to treat a
tree at the standard dosage rate. Ambrosia beetle mortality can occur within
10-14 days and continue for up to two years. A heavily infested tree or a tree in
obvious mortality spiral is a poor candidate for treatment. The vascular system of a dying tree is
not capable of transporting adequate nutrients or chemical treatment for
recovery. It is important to be
able to diagnose beetle infestation as early as possible. Please see the prioritized list of
symptoms above.
