Biological control of cereal seed-borne diseases by seed bacterization with greenhouse-selected bacteria

About 400 bacterial strains, isolated from roots of wild and cultivated plants, were screened for effects against diseases caused by Drechslera teres and/or Microdochium nivale in greenhouse tests and against common bunt caused by Tilletia caries in field tests. Four of the strains showed good biocontrol activity <70% disease reduction) against D. teres and T. caries both in screenings and field tests. One Pseudomonas isolate, MA 342, strongly and reliably suppressed both D. teres and T. caries in the field, while effects against M. nivale were weaker. The effects could not be enhanced by varying pre-application or seed application procedures. This isolate could be stored as a suspension in a refrigerator, frozen or applied to seeds for at least one month without loosing its disease controlling ability.     

Beschreibung des Feuerbrandbefalls am Institut für Obstzüchtung in Dresden-Pillnitz im Jahr 2003

The orchard of the Institute of Fruit Breeding of the German Federal Centre of Breeding Research on Cultivated Plants in Dresden-Pillnitz was highly affected by fire blight in 2003. Infected pomefruit trees were observed over a period of nearly 3 months. The first symptoms on pear trees were found on May 19th. The pathogen Erwinia amylovora was confirmed officially on May 26, and the last infected apple trees were detected the 11th of August. The infected trees had to be grubbed at the decision of the Phytopathological Authority. In total, 1164 apple and 478 pear trees were grubbed, including the entire pear collection of the gene bank. Of 35 wild species of pear, 49 accessions, eight accessions of six species each, showed infections. The apple collection of the gene bank included 33 wild species, with 365 accessions, and 845 cultivars and clones. Ten accessions of nine wild apple species and 81 cultivars/clones of these collections showed fire blight infection. The source of infection was the pear collection, and the distance from that source was important for the occurrence of infection. Field plots close to the pear collection had tree losses of 10–34%, while more distant plots had losses of 0–6%. Around 80% of the lost apple trees were detected and grubbed from 27th May to 11th June. Some of the cultivars bred in Dresden-Pillnitz, e.g. ‘Pilot’ and ‘Rekarda’, were affected by fire blight in most field plots, whereas most others were affected mainly only in plots adjacent to the infection source. A correlation of r=?0.72 could be calculated for rating in artificial shoot inoculations and percentage of trees of resistant cultivars lost. The cultivars ‘Pirol’, ‘Reanda’, ‘Remo’, ‘Rene’, ‘Renora’, ‘Resi’, and ‘Retina’ showed only a very low numbers of infected trees. No tree of ‘Rewena’ showed symptoms of fire blight. Despite a tendency to postblooming, only 8.9% of ‘Pinova’ trees had to be grubbed.     

Effectiveness of plant extracts of Paeonia suffruticosa and Hedera helix against diseases caused by Phytophthora infestans in tomato and Pseudoperonospora cubensis in cucumber

Journal of Plant Diseases and Protection - The effects of ethanolic extracts (20 % per fresh weight (Fw) or 6 % per dry weight) of 20 different plant species were tested against late blight...