. Protecting and enhancing America's forests and rangelands : 1986 research accomplishments. Forests and forestry United States; Rangelands United States. Pinewood Nematode in Exported Southern Pine Chips Recently the Nordic countries placed an embargo on importation of pine chips and other raw softwood products from the United States after imported chips were found to be infested with the pinewood nematode, which causes the pine wilt disease. Although this disease is minor in the United States, some European pine species are known to be highly susceptible. Curtailing chip exports represents a
. Protecting and enhancing America's forests and rangelands : 1986 research accomplishments. Forests and forestry United States; Rangelands United States. Pinewood Nematode in Exported Southern Pine Chips Recently the Nordic countries placed an embargo on importation of pine chips and other raw softwood products from the United States after imported chips were found to be infested with the pinewood nematode, which causes the pine wilt disease. Although this disease is minor in the United States, some European pine species are known to be highly susceptible. Curtailing chip exports represents a serious loss to the forest industry. Researchers at the Southeastern Station are currently studying how the nematode becomes established in pine chips, what influences its survival in chip piles at export terminals, and how it might be eradicated from chips before and during export. The nematode infests wood through the activities of insect vectors, most commonly the pine sawyers. These beetles colonize pine logs and bolts held in storage yards or standing dead or weakened trees, and introduce the nematode while laying their eggs. The nematodes remain alive after the wood is processed into chips and feed on fungi that colonize the chips. The survival of the nematodes in chip piles is mainly governed by temperature. Though temperatures near the shell of a chip pile may be lower than in surrounding air, heat near the center of the pile can exceed 60 C. Optimum temperature for reproduction of the nematode in chips is 35 to 40 C, but populations rapidly decline above 45 C. At 60 the nematodes are killed in 1 hour or less; thus none survive in the center of large piles. However, the nematodes do survive in parts of the pile where temperatures are more favorable. Nematodes can also reproduce in ship's holds during ocean crossings since the temperature in the lower part of the cargo hold averages about 35 °C It is not economically feasible to use heat to control the nematode because
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