Pseudomonas meeting - Cost 873

BACTERIAL DISEASES CAUSED BY PSEUDOMONAS SP. OF STONEFRUITS AND NUTS IN SLOVENIAIgor Zidarič 1 , dr. Tanja Dreo 21 Agricultural Institute of Slovenia, SI-1000, Ljubljana, Hacquetova 17, Slovenia2 National institute of Biology, SI-1000, Ljubljana, Večna pot 111, SloveniaIn spite of limited environmental factors for fruit production, Slovenia may still be considereda traditional fruit growing country. Fruit growing was the most advanced between 1920 and1950 when, beside apple orchards, the production of cherries and plums was important. Atthat time the major part of the fruit mentioned above was exported. Until the mid-nineties ofthe 20 th century the stone fruit production witnessed a strong reduction leaving only a fewhectares of cherry and plum orchards; meanwhile, the peach production did not changeessentially. The production of nuts in the past was more or less extensive. The situation haschanged a little over the last 15 years since the size and the production of stone fruit andespecially that of nuts have increased strongly. Enlargement of orchard size and increase offruit production, open market for planting material, and climate changes caused theappearance of certain pests and diseases which were not present or may not have been noticedbefore. In the past years the fruit growers have observed the appearance of suspicious diseasesymptoms, especially on hazelnuts, peaches, apricots and cherries. Some of the plantationswere inspected by staff members of Plant Protection Department. Our first findings werepointed at a bacterial origin of the disease symptoms. Pathogenic bacteria may belong to thegenus Pseudomonas sp. Some peach, apricot and cherry samplings were carried out in thefield. Among bacteria of the genus Pseudomonas sp., laboratory analyses confirmed only thepresence of the bacterium Pseudomonas syringae on cherries and apricots. Characterisationand confirmation of pathovar has not been carried out yet, however, we suspect that we havebeen able to isolate two different bacteria, i.e. Pseudomonas syringae pv. morsprunorum andPseudomonas syringae pv. syringae which was determined using IF and BIOLOG system.Further determination and confirmation of pathovars is still in progress. At peach samplingwe succeeded in isolating and confirming only the bacterium Xanthomonas arboricola pv.pruni. In the future we intend to perform intensive research of the presence of pathogenicbacteria of the genus Pseudomonas, determine, in the field, their spreading, potential dangerfor host plants and producers. We will try to determine the origin of bacterial diseases andrestrain their possible spreading and of course determine the Pseudomonas sp. pathovars.11