SEPTOCYTA RUBORUM: OCCURENCE AND POSSIBILITY OF DISEASE CONTROL IN SERBIA

Purple blotch of blackberry, the disease caused by Septocyta ruborum (Lib.) Petrark, was described in Serbia in late 1980s, but in recent years this disease caused significant looses in blackberry production in Serbia. The characteristic symptoms of purple blotch were observed with strong intensity on blackberry plants at the Trnavci (Aleksandrovac) locality. The fungus was isolated on PDA medium, from the symptomatic shoots of blackberry, using standard mycological methods. Based on pathogenicity and morphological properties, the isolated fungus was identified as Septocyta ruborum. Total nucleic acids were extracted from mycelium of the monosporial culture, dissolved in TE buffer, and maintained at -20°C. Polymerase chain reaction (PCR) assay was performed using ITS1/ITS4 primer pair. The obtained amplicon was purified and sequenced. The obtained sequence (488 bp) was deposited in the National Center for Biotechnology Information under the accession number JN133277.
In order to control the causal agent of purple blotch of blackberry, the effectiveness of eight synthetic fungicides was evaluated during 2007 and 2008 in the locality where the fungus was isolated. The following fungicides were tested: Quadris (azoxystrobin), Cabrio top (pyraclostrobin + metiram), Signum (boscalid + pyraclostrobin), Stroby DF (kresoxim-methyl), Dakoflo (chlorothalonil), Polyram DF (metiram), Cuproxat (copper tribasic sulfate), and Bordeaux mixture 100 SC (copper II sulphate + calcium hydroxide). A complete randomized block design with four replicates per treatment was used. Mean percent disease control values were calculated from the evaluations made towards the end of the trials, when differentiation between treatments was most obvious. Data were analyzed by one-way completely randomized ANOVA, and means comparison performed by Duncan's test. In 2007, all fungicides were effective against S. ruborum and there was no significant difference among their efficacies. In 2008, four tested fungicides significantly reduced the diseases severity: Quadris (98.9 and 99.8%), Cabrio top (98.7 and 99.8%), Bordeaux mixture 100 SC (98.5 and 99.2%), and Signum (95.7 and 99.0%). There was significant difference among efficacies of these four fungicides compared with other tested fungicides.