Nutrient deficiency symptoms associated with sugar maple dieback and decline in the Quebec Appalachians

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Abstract
The most widespread visual symptoms of nutrient deficiency in declining stands of sugar maple (Acersaccharum Marsh.) south of the St. Lawrence River in Quebec over the last 3 years were those of K and (or) P. Typical symptoms are described and illustrated in this paper. Dark green foliage, frequently accompanied by leaf curling, appears to be an early manifestation of an insufficient supply of K. With time, chlorotic and necrotic foliage, mostly in the upper crown, revealed the existence of acute K deficiencies, with concentrations in the range of 0.20–0.30% in July. Phosphorus deficiency showed up as small, purple leaves, especially sun leaves, with P concentrations of 0.05–0.08% in the midst of the growing season. Phosphorus deficiency was most frequently accompanied by low or deficient K concentrations, in which case symptoms were more complex. Measured K and P concentrations in freshly fallen leaf litter of deficient trees were ca. 0.10 and 0.02%, respectively, well below published values for sugar maple leaf litter.