The efficacy of a seed treatment of oilseed rape (OSR) (Brassica napus) with the rhizobacteria Serratia plymuthica (strain HRO-C48) and Pseudomonas chlororaphis (strain MA 342) applied alone or in combination against the blackleg disease caused by Leptosphaeria maculans was tested with different cultivars. Seeds were soaked in bacterial suspensions (bio-priming) to obtain log 10 6-7 CFU seed −1 . Cotyledons were inoculated with a 10 ul droplet of L. maculans spore suspension of log 10 7 spores ml −1 and the disease index (size of lesions) was evaluated 14 days later. A mean disease reduction of 71.6% was recorded for S. plymuthica and of 54% for P. chlororaphis. The combined treatment was not superior to the treatment with S. plymuthica alone. The reduction of the disease caused by S. plymuthica was independent of the cultivar's susceptibility, whereas the control effect recorded with P. chlororaphis increased with decreasing cultivar resistance to blackleg disease. The bacterial colonization of OSR was restricted to the roots and hypocotyl. No significant difference in bacterial colonization of the rhizosphere was observed between different cultivars, nor between single or combined bacterial seed treatments.

The ability of different bacteria to inhibit Orobanche radical elongation was examined. Seeds of Orobanche aegyptiaca Pers. and O. cernua Loefl. were induced to germinate with the Growth Regulator GR24 in the presence or absence of test bacterium. Radical lengths were estimated microscopically on a scale relative to seed length (0Á5 seed lengths) after 5 days of incubation at 258C. The results indicated that Pseudomonas aeruginosa QUBC1, P. fluorescens QUBC3, Bacillus atrophaeus QUBC16, and B. subtilis QUBC18 significantly inhibited radical elongation (P50.01) of both O. aegyptiaca and O. cernua relative to control radicals, whereas Microbacterium hydrocarbonoxydans QUBC11 and Ochrobactrum anthropi QUBC13 showed less inhibitory effects. Other bacterial isolates had no inhibitory effects. Bacterial isolates were identified using the universal method in addition to morphological and biochemical features. The establishment of the inhibitory effect of the most promising isolates, B. atrophaeus QUBC16 and P. aeruginosa QUBC1 on radical elongation of both Orobanche spp. is a step towards utilizing such bacteria as biocontrol agents against O. aegyptiaca, O. cernua, and potentially other Orobanche species.

Differential resistance of oilseed rape cultivars (Brassica napus ssp. oleifera) to Verticillium longisporum infection is affected by rhizosphere colonisation with antagonistic bacteria, Serratia plymuthica and Pseudomonas chlororaphis Abstract The effect of a seed treatment with the antagonistic bacteria Serratia plymuthica (strain HRO-C48) and/or Pseudomonas chlororaphis (strain MA 342) on the infection of oilseed rape with Verticillium longisporum was assessed with ten different cultivars. Soil was inoculated with microsclerotia and mycelium of a V. longisporum culture. Seeds were treated with rifampicin-resistant antagonistic bacteria at a rate of log 10 6-7 cells per seed. Resistance against V. longisporum infection did not differ between cultivars and was generally low. A significant disease reduction recorded as area under disease progress curve (AUDPC) was obtained with both antagonistic rhizobacteria with no significant difference between the treatments. Percent of healthy plants was approximately 70% in all bacterial treatments. Significant differences were observed between the cultivars ranging from 46.5% (cultivar Titan) to 72.6% (Trabant). The combined use of both bacteria could not provide additional control effects. The bacterial density in the rhizosphere was not related to the control effect, but increased by log 10 2 on infection with V. longisporum. Growth promotion effects were also not related to the control effect. At present, neither the application of chemical fungicides nor breeding for resistance against V. longisporum in oilseed rape can provide a solution for this increasingly problematic plant pathogen. The present results now open perspectives to control V. longisporum in oilseed rape by making use of cultivars, which express resistance against this pathogen on interaction with the antagonistic rhizobacteria S. plymuthica or P. chlororaphis.

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Olive Leaf Spot (OLS) is found in many parts of the world and cause readuced growth and yield in olive trees. In this study, investigations were carried out to measure the incidence (% infected leaves) and severity (number of lesions/leaf) of OLS in olive growing regions in Palestine, including the regions of Hebron,