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We are now seeing Austrian Pines dying at a
nearly similar rate to Scotch Pines from Pine Wilt Nematode.
In past years, nematode infection has occurred
at about a 20:1 ratio, the long-horned beetle insect vector much
preferring the Scotch Pine. This has now changed. As our Scotch
Pine population declines, the insect vector has begun to attack
trees that she can find, and that is the Austrian, the Ponderosa,
and to a lesser degree, the Red Pines.
Chemical control of the nematode has been
available for some time. Unfortunately, it's very expensive,
and has only about a 90% success rate over two years, and a 70%
success rate over three years. We have not advocated its use.
We have argued that Austrian Pines were worth
"defending" against the various fungi that attack them, whereas
Scotch Pines should be considered a wasting asset. These new facts
may well change our mind. We'll have to watch the year-to-year
trend. |
