Fungus diseases of raspberry (Rubus idaeus L.) in Finland

Abstract

During 1978—1981 a total of nearly 200 raspberry cane samples were investigated originating mainly from southern and eastern Finland. The samples consisted of young and already fruited canes injuried to different degrees. Phoma sp., the conidial stage of Didymella applanata (Niessl) Sacc., causer of raspberry spur blight, was most common of the isolated fungi; the perfect stage did not develope until afer preservation in cold. The peak of pycnospore release on raspberry canes was in July 1981. Other weak wound pathogens were isolated: Fusarium avenaceum (Cda. ex Fr.) Sacc., which occurred in 22 % of the transfers, F. culmorum (W. G. Sm.) Sacc., Botrytis cinerea Pers. ex Fr. and the secondly most common Phoma species, P. exigua Desm. v. exigua Maas. The fungi mentioned above were mainly obtained from different depths of the raspberry stem tissues, the least on an average from the pith. Alternaria alternate (Fr.) Keissl. was the most common ’surface fungus’, Phialophora spp., wood rotting saprophytes, common also in the pith. Leptosphaeria coniothyrium (Fckl.) Sacc., the most strong of the pathogens, was rare in the samples. The occurrence of Cylindrocarpon destructans (Zinssm.) Scholten in root samples changed 8-70 %. The cv. Muskoka is more susceptible to spur blight than cv. Ottawa. On the other hand, the larvae of raspberry cane midge (Resseliella theobaldi (Barnes)) produced plenty of injuries in Ottawa-samples originating from Mikkeli in 1980 and thus increased also the fungal damage.