RECENTI ACQUISIZIONI SULLA EZIOLOGIA DELLE "MACCHIE BRUNE" DEL NOCCIOLO
From 1980 field and laboratory investigations have been carried out to verify nature and etiology of these alterations and the following results have been obtained:
- it is a physiological disorder caused by unfavourable environment conditions;
- about the etiology it is necessary distinguish between predisposing and inducing causes; the most important predisposing factor is the age, because usually simptoms do not appear in organs under twelve years old; among inducing causes reciprocal competition and various stresses play the leading role;
- the disease is appeared almost simultaneously on an extensive area of Piedmont and even in different cultivars;
- affected branches usually do not dry but plants react producing an healing callus; severe decaies and dyings take place quite rarely only on trunks showing very numerous spots and on trunks where establish wound pathogens like fungi Basidiomycetes and Deuteromycetes belonging to the genera Phomopsis and Cytospora.
To prevent the appearance of the disease it is usefull to take the following measures:
- to choose in new orchards quite large planting space;
- to keep no more than four trunks for bush;
- to prune regularly to avoid that plant develop excessively;
- to pinch out shoots every year;
- to keep plants in excellent vegetative conditions by means of chemical and specially organic fertilizers and, if possible, to irrigate in case of long-time water stress.