Invasive Shot Hole Borers (ISHB) (Part II)
When the beetles bore
into a tree, they create a series of tunnels where they farm the fungus and produce
young. This series of
tunnels is referred to as a gallery. Their
winding galleries can reach to a depth of around 3 inches (8 cm) into the
tree's wood. The
dark stains in the wood is caused by the fungus (Fusarium euwallaceae),
which not only causes the beetle's galleries to be stained black, but also
moves into the tree's xylem, clogging it. The clogged xylem will prevent the tree from distributing water and nutrients and leads to branch dieback and the eventual death of the tree.
The Fusarium can also cause a sugary
exudate (also called a sugar
volcano) and gumming. While inspecting trees you may also see the beetle
entry & exit holes (about 0.85 mm or
the size of pen head in diameter) and sometimes you can see the abdomen of a female beetle sticking out of the hole.
Fusarium in the gallery and branch dieback in oak.
Beetles and Galleries in the wood.
An infected Sycamore tree that was removed due to potential fire hazard and property destruction in Montecito.
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