Imported wood-eater raises alarm for coniferous forests

THESSALONIKI – As if fires, quarrying and human encroachment on land were not enough, Greek conifer forests may face an airborne enemy which has the experts worried. Bursaphelenchus xylophilus, a kind of nematode (roundworm), is invisible to the naked eye but wreaks visible destruction in forests. Insects transfer nematodes from one conifer to another, say phytopathologists at the Thessaloniki Forest Research Center. They enter tree trunks and, in favorable weather conditions, can eventually kill off trees. The European Union has taken measures to deal with the danger of imported nematodes in coniferous forests (Directive 77/93 EEC), and recommends regular laboratory tests. Samples have been taken more frequently since Bursaphelenchus xylophilus in Europe was found in Portugal in June 1999. Greek scientists are worried because the climate here generally favors the establishment and growth of B. xylophilus. Phytopathologist Maria Kalapanida explains that B. xylophilus can be transported in unprocessed wood and in wooden packaging, such as crates. B. xylophilus is native to North America, where coniferous forests have developed a resistance to it. Imported to Japan, however, it has caused tremendous damage, resulting in losses of up to 2.5 million kilometers (1.6 mln miles) of timber a year. Trees in coniferous forests in Greece and along the Mediterranean coast of Europe can dry out. The outbreak at Seich-Sou in Thessaloniki this year has been attributed to the weather and other species of Bursaphelenchus which are carried by wood and bark-eating insects, and are related to but not as harmful as B. xylophilus, which has not yet been found in Greece. The most common nematode in Seich-Sou is B. sextentati, which is usually spread by a small insect called Blastophagus piniperda. «The insect itself damages the bark, but the nematode causes worse damage,» says Kalapanida. Chemical sprays used to kill these insects are not appropriate for a man-made park near a city, so the Thessaloniki Forestry Service fells and removes 2,000 to 6,500 kilometers of diseased timber every fall. THURSDAY