Evaluation of several apricot cultivars and clones in the Lower Silesia climatic conditions. Part II: Vigor, health and mortality

Vigour, health and mortality were assessed in several apricot cultivars in two experiments conducted from 1988 to 2005 at the Fruit Experimental Station near Wroclaw in south-western Poland. In the first experiment, the cultivars studied were 'Harcot', 'Morden 604' and 'Early Orange'. All were grafted on 'Myrobalan' seedling rootstock. In the second experiment, the cultivars evaluated were 'Early Orange', 'Harcot', 'Morden 604', 'Moorpark', 'Somo', 'Bergeron', 'Hargrand', 'Karola', 'Ungarische beste', 'Veecot', 'Velkopavlovicka LE 12/2', 'Velkopavlovicka LE 19/2' and three clones which had been bred at the Fruit Experimental Station in Albigowa: LS-4, LS-5 and LS-7. All were grafted on 'Somo' seedling rootstock. Vigour depended on both the cultivar and the rootstock. The most vigorous genotypes were 'Morden 604', 'Moorpark', 'Velkopavlovicka LE 12/2, 'Veecot' and LS-4. The least vigorous cultivars were 'Early Orange', 'Bergeron' and 'Karola'. Cultivars grew more vigorously when grafted on 'Myrobalan' seedling rootstock than on 'Somo' seedling rootstock. Mortality was especially high in 'Morden 604'; probably because of incompatibility with the 'Somo' seedling rootstock. Susceptibility to cankers was lowest in 'Karola', 'Somo', 'LS-4' and 'Early Orange'. Susceptibility to Monilia laxa Sacc. was lowest in 'Hargrand', 'Bergeron' and 'Somo'.