Developing sanitary measures to improve nursery hygiene in seedlings grown for Christmas tree and bough production

In many nordmann fir (Abies nordmanniana) Christmas tree plantations in Norway there are problems with heavy needle cast. The fungus Rhizosphaera kalkhoffii is often detected in dying needles falling off on lower branches. R. kalkhoffii is a well known pa thogen in Christmas tree production both in Europe and USA. Another even more serious needle cast, is green, current season needles falling off during the winter, both on newly harvested trees and in the field. This needle cast is mainly located on the to p shoot and the upper branches. The cause of this damage is not yet understood, but two fungi have been found in association with this needle cast; Thysanophora penicillioides and a not yet identified fungus. The latter was found in April 2004 on up to 73 % of the loosely attached needles. T. penicillioides is a cosmopolitan organism, but it is not considered a damaging agent. Except for a publication from Finland, where T. penicillioides is recorded as an endophyte on Norway spruce (Picea abies), all lite rature describes it as a saprophyte. Findings from Norway strongly indicate that T. penicillioides is a parasite. T. penicillioides has also been found on nordman fir in nurseries in Norway. Surveys have shown that a number of problematic diseases in prod uction fields are introduced from nurseries via infested transplant material. This project aims on finding the exact cause for the extensive needle cast to gain control of the problem at nursery level. To reach that goal inoculation tests with the differe nt fungi associated with needle cast will take place, different fungicides and biological control materials will be tested and infection periodes for the different fungi will be established.