Nutrient Deficiency of Spruce Needles Caused by Root and Butt Rots - A Factor in Forest Decline

Acute needle yellowing of spruce (Picea abies) followed by forest decline has been observed in different parts of Austria. Trees with "needle yellowing" usually show specific nutrient deficiency, whereas trees of normal colour appear to be adequately supplied. Twenty-one healthy and 21 diseased spruce trees on 3 different forest sites in Austria were felled and examined for root and butt rots; the nutrient content of needles, root and stem sapwood was compared. Trees with active needle yellowing had significantly higher rates of root and/or butt rot, low levels of potassium, calcium and magnesium in the sapwood of roots and lower stem parts. Acute yellowing as a symptom of mineral deficiency therefore is induced by physiochemical reactions like the reinforcement of cell walls and the compartmentalization of wood after fungal attacks rather than by leaching.