Diagnostic leaf analysis for stone fruit. 4. Plum

Abstract

Changes in the leaf composition of Prunus domestica cv. D'Agen and P. salicina cv. Mariposa, were measured monthly during the 1971 -72 and 1972-73 seasons in New South Wales. The rate of change of leaf composition was least during January-February for D'Agen and during December-February for Mariposa. Thus, leaf composition standards should be based on January-February samples for D'Agen and December- February samples for Mariposa, and diagnostic sampling should be confined to these periods where possible. Correction factors for adjusting the composition of early or late samples back to January 31 levels, were calculated for D'Agen from polynomials with time fitted to the leaf composition data. A survey of the leaf composition of well-managed orchards was also conducted each January from 1971 to 1973. Of the European prune orchards surveyed, 51 per cent were low in nitrogen, 37 per cent were low in phosphorus, 28 per cent were low in iron, 25 per cent were high in copper, 10 per cent were high in manganese and 23 per cent were high in boron. Of the Japanese plum orchards surveyed, 33 per cent were high in nitrogen, 14 per cent were high in potassium, 22 per cent were low in calcium, 18 per cent were high in copper and 15 per cent were high in manganese.