Keywords: Micronutrients, Tree Nutrition, Orchard management, Tissue analysis, Leaf composition, Deficiency symptoms.

Micronutrients which are critical to the biochemical and physiological functions involved in the vegetative and reproductive activities of fruit trees are identified. The main micronutrients (Fe, Mn, Zn, Cu, Mo, Ni, B, Cl, Co and Si) are present in small quantities in plant tissues and the requirement is also very low. Their availability and uptake by the roots is related to the soil, climatic conditions and to the genetic characteristics of the fruit tree and rootstock. Antagonism and synergy between nutrients can influence plant health and a correct balance of elements is fundamental to good orchard management. Deficiency or excess in soil or in plant tissue can be determined by chemical analysis and the optimal concentration assessed for diagnosis and for the correct treatment in the orchard. Iron, manganese, zinc, copper, boron and other micronutrients are considered and symptoms on leaves, fruits and trees are discussed; practical indications for field applications are suggested. Micronutrient toxicity in soils and plants must also be considered in relation to the environmental health of orchard ecosystems.

B. Marangoni, G. Marcolini and M. Toselli, Dipartimento di Colture Arboree, University of Bologna, Viale Fanin 46, 40127 Bologna, Italy.

12 Pages, 1 Plate, 3 Tables, 28 References.