Nematological problems in the production of conifers.

Forestry and its products play an important part in thc economy of Piedmont, and recently foresters are considering environmental and social values as well as wood and timber yield. This reappraisal, which results in a significant increase in the social and economic value of forests, explains the present high demand for seedlings and the intensive studies of nursery problems, which arc currently being carried out. Nursery seedlings arc particularly vulnerable to nematode damage because of the maintenance of high soil moisture and fertility levels for optimum plant growth and the uninterrupted cultivation of the same or of closely related plant species within the same area; all of these factors create an environment favorable for nematode development; nematodes also predispose tree roots to invasion by soil-borne fungi, incapable of colonizing nematode-free roots.