Foliar symptoms on norway spruce and relationships to magnesium deficiencies

Crown symptoms, foliar and soil nutrient status, disease and insect presence in Norway spruce (Picea abies L.] Karst.) were evaluated in twelve plantations across West Virginia, Pennsylvania, New York and New Hampshire during 1987 to 1988. The most obvious crown symptoms observed under plantation conditions were thinning and chlorosis. These symptoms were similar to those observed on this species throughout the past decade in central Europe and specifically in the Black Forest of the Federal Republic of Germany. A crown vigor index (CVI) was calculated for each tree to classify health status. Of the 180 trees sampled, 247 were healthy; 517 were intermediate, and 257 had severe crown symptoms. The symptoms varied from state to state, plantation to plantation, and from tree to tree. The most severe symptoms were noted on trees at Plantation 12, near Davis, WV. Severe symptoms were also noted on trees within Plantations 4 and 5 in the Tug Hill Plateau region, NY, and within Plantation 3 near Donegal, PA. Two entire branches were removed from the top crown and mid-live crown, respectively, of each sampled tree. Based on laboratory observations, the most common needle symptom was a uniform chlorosis. Chlorotic spots on needle surfaces were the second most common symptom. Thirteen major and trace foliar nutrient elements were determined. Average foliar Mg concentrations of symptomatic trees within several plantations ranged from 0.022 to 0.0637; levels less than the accepted deficiency threshold value. There were significant (negative) correlations between the mean foliar Mg concentrations for the trees and their corresponding CVI and mean discoloration indices of needles. Corresponding soil pH, available P, exchangeable cations, 7 saturation of K, Mg, and Ca of soils were determined for each tree. Soil pH, exchangeable Mg and 7 saturation of Mg were significantly lower in the more symptomatic Norway spruce.