Survey of resistance in some Prunus species in Japan against blossom blight caused by Monilinia laxa ([Aderh. and Ruhl.] Honey)

It was investigated that the reaction of Prunus spp. cultivars including apricot (P.armeniaca L., P. armeniaca var. ansu Maxim. and their hybrids), Japanese apricot (P. mume Sieb. et Zucc.) and interspecific hybrids among P. salicina Lindl., P. mume Sieb. et Zucc. and P. armeniaca L. attacked by Monilinia laxa ([Aderh.&Ruhl.] Honey) in a high humid region of Tsukuba, Ibaraki, Japan in the spring of 1995. The percentage of damages of each investigated cultivar was rated three times by separate visual observations. Almost all of the apricot cultivars were damaged very severely except for the two cultivars : 'Banseiomi', belonging to P.armeniaca var. ansu, Maxim, and 'Shinyo', a hybrid between P. armeniaca and P. armeniaca var. ansu. On the other hand, Japanese apricot cultivars and several clones of interspecific hybrid showed little damages. The reliability as donors for resistant apricot breeding against this disease is discussed.