Fire blight is the most destructive bacterial disease of rosaceous plants containing berry fruits. The present study was conducted to determine host resistance among the extensively grown raspberry cultivars (Willamette, Rubin ve Aksu Red, Heritage, and Royalty) and blackberry cultivars (Bursa-1, Bursa-2, Bursa-3, Chester, Loch Ness, and Jumbo) to Erwinia amylovora, which is the causal agent of the fire blight disease. In the greenhouse and field experiments, the plants were inoculated with two virulent strains of E. amylovora to evaluate whether cultivar–strain interactions exist. Disease index (%) and disease severity (%) were determined regarding diseased plant symptoms and classified into four susceptibility groups (HR, MR, S, and HS). Raspberry cultivar Willamette and blackberry cultivar Bursa-1 appeared to be highly susceptible with average 50% disease severity ratings. One of the raspberry cv., Royalty, was moderately resistant with an average 25% disease severity rating. This is the first study determining resistance reactions of native and common blackberry and raspberry varieties against fire blight in Turkey. As the cultivation of berries expands to new regions and larger acreages, a serious outbreak of fire blight may be potentially much more destructive in the future. Therefore, phytosanitary measures are needed to prevent any further spread of the bacterium to new blackberry- and raspberry-growing areas. The study will serve as an initial guide for growers and breeders for their appropriate raspberry and blackberry selections in Turkey.
Kubilay Kurtulus Bastas and Fikrettin Sahin
Sezai Ercisli, Ahmet Esitken and Fikrettin Sahin
During Fall and Winter 1999-2000 and 2000-2001, a study was conducted to evaluate the effects of exogenous IBA application (0, 2000, or 4000 ppm) and inoculation with Agrobacterium rubi (strains A1, A16, or A18) alone or in combination with each bacterial strain on rooting of hardwood stem cuttings of two rose selections (ERS 14, Rosa canina, and ERS 15, Rosa dumalis). Treatments of hardwood stem cuttings with IBA, bacteria alone and in combination with IBA were found to promote rooting. The highest rooting percentage was obtained among ERS 14 cuttings when treated with 4000 ppm IBA plus A. rubi A16. However, optimal rooting of ERS 15 was obtained when treated with 2000 ppm IBA plus A. rubi A18. Better rooting was observed in thornless ERS 15 genotype than in thorny ERS 14 genotype in both years. Chemical name used: 1H, indole-3-butyric acid (IBA).