LEAF ANALYSIS OF PEACH AND APPLE TREES IN ITALY (SUMMARY)

Leaf analysis as a method of estimating fertilizer requirements has been studied mostly on peach trees and, to a lesser extent, on apple and pear.

The standard data for optimum range of nitrogen, phosphorus and potassium on leaves collected at the end of July have been established.

Surveys on peach nutrition as determined by leaf analysis, in the most important Italian areas, have shown:

1. a trend toward an ‘optimum’ leaf concentration of nitrogen in the Po Valley, associated with high yields;
2. high and even excessive potassium content of the leaves in central and southern districts;
3. generally satisfactory level of leaf phosphorus;
4. early fruit thinning increased potassium content of the leaves;
5. in the Po Valley spring rains had consistent effects upon the leaf mineral content.

In apple orchards, the application of increasing amount of nitrogen to young Red Delicious trees increased both nitrogen level in leaves and flower bud initiation.

In biennial bearing Golden Delicious a positive relationship has been established between leaf nitrogen and the ‘off year’ yield.

The widening of the N/K ratio was associated with a delay of fruit ripening and an increase of Gloeosporium infections.

In recent investigations on Red Delicious apple decline in acid soils of north-west Italy, a high level of leaf manganese was found, supporting the hypothesis of manganese toxicity.

In apple and peach studies no definite relationships were established between soil test data and leaf analysis for nitrogen and phosphorus. In some cases, a positive correlation for potassium was found.