Plant-Parasitic Nematodes of Jack and Red Pine Stands in Wisconsin * )

Abstract

Relatively high populations of Xiphinema americanum and moderate numbers of Trichodorus californicus were found in both declining and healthy jack pine plantations. Natural stands of jack pines and red pine plantations, which usually are not affected by the decline, had few X. americanum. Maximum numbers of dagger nematodes occurred at soil depths of 6 to 13 cm where the maximum number of lateral roots of jack pine were also found. Other plant-parasitic nematodes occurred in low numbers. Populations of hand-picked X. americanum decreased on jack pine in greenhouse experiments during the first 6 months after inoculation, then increased slowly but induced little damage. The number of dagger nematodes added to red pines continued to decrease. Nematodes were not implicated as a major factor in decline of jack pine plantations.