Taksterfte bij bramen veroorzaakt door Septocyta ramealis (Rob.) Pet.

Summary

In some years in the Bommelerwaard province of Gelderland, die-back of blackberry can do considerable damage. One of the causes is the fungusSeptocyta (Rhabdospora) ramealis (Rob.) Pet. In a garden where blackberries have been under observation for the last two years, the stems were covered on 19 March 1952 with dark purplish-brown spots, in which numerous pycnidia were found (fig. 1). However, die-back, which was very severe in this garden in 1951, occurred only to a slight extent in 1952. In spore-trapping experiments (fig. 3) pycnospores were caught from the beginning of April until the end of August, with a marked maximum in June (fig. 4). In dry or nearly dry periods no spores were trapped. During summer and until the last observation on 10 September no new infections on the young vegetative branches could be found On 23 October the first spots were observed especially on the lower parts of the shoots. From incoculation experiments it became clear that the appearance of the spots is promoted by a cold treatment. Inoculated plants, kept for 6 weeks at 4°C in an illuminated cool-room, showed symptoms a week after their removal, whereas plants inoculated at the same time and kept in a greenhouse at room temperature showed no symptoms.

Control of the disease must be directed mainly towards protection of the young vegetative parts by spraying. Also, since in propagation young shoots are used which are still connected with the terminal part of the old branch on which they developed, this terminal part should be removed in early spring, as it is often covered with spots of Septocyta (fig. 2). This should help to prevent infection of the young plants, which are probably the means by which the disease is carried to new gardens.