First report of Amylostereum areolatum in pines in the United States
The wood decay fungus Amylostereum areolatum (Fr.) Boidin, native to Eurasia and North Africa (4), is the mycosymbiont of several siricid woodwasps including Sirex noctilio Fabricius, a major pest of pines in New Zealand, Australia, South America, and South Africa where it has been introduced. Adult females of S. noctilio are effective vectors of arthrospores (hyphal fragments) of the fungus, stored internally within mycangia in the abdomen, which are injected with the eggs and a phytotoxic mucus into the outer sapwood of coniferous tree hosts during oviposition. The toxin is translocated upward into the foliage causing needle wilting, necrOSiS, and crown dieback. The fungus decays the wood (white rot) and provides food for hatching larvae that form borer galleries. Extensive damage to the host via wood decay, galleries, and toxin effects cause mortality in heavily infested trees. S. noctilio adults have been intercepted from several locations in North America prior to 2003, but there has been no evidence of an established population in any native forests until recently.