Journal of Plant Pathology (1999), 81 (3) Seventh SIPaV Annual Meeting 227 RECENT ADVANCES IN STUDIES ON SPECIES OF PHY- TOPHTHORA ASSOCIATED WITH INK DISEASE IN ITALY. N. Anselmi, A.M. Vettraino, G. Natili and A. Vannini*. *Dipartimento di Protezione delle Piante, Università della Tuscia di Viterbo, Via S. Camillo de Lellis, I-01100 Viterbo, Italy. Fax +39.761.357473; e-mail: vannini@unitus.it A serious recrudescence of ‘ink disease’ has been reported in the recent years in a number chestnut stands in Italy. Two species have been suggested as causal agents of the disease in these areas, Phytophthora cambivora and to a less extent P. cinnamomi; fur- thermore it cannot be excluded that other species could con- tribute to the development of the disease. A large number of soil sample has been collected under diseased and healthy looking trees in two chestnut areas in central Italy with the aim of deter- mining the number of species of Phytophthora associated with ‘ink disease’ in Italy. The identification of the isolates has been carried out with classical morphological methods and through RFLP analysis of the ITS1-5,8S-ITS2 region. Five species were isolated from soil in infected areas: P. cambivora, P. cactorum, P. citricola, P.gonapodyides and P. cryptogea. However only P. cam- bivora has been found always associated with diseased trees and isolated from symptomatic tissues. Pathogenicity tests with inocu- lated cuts and through soil infestation, confirmed the high viru- lence of P. cambivora. However all the species resulted pathogen- ic on inoculated chestnut cuts but only P. cambivora and P. citri- cola were able to kill one-year seedlings following soil inoculation. These preliminary results would suggest that more than one species of Phytophthora could be responsible of ‘ink disease’ in Italy. MECHANISMS OF ACTION OF CANDIDA OLEOPHILA IN RELATION TO THE BIOSYNTHESIS OF β-1,3-GLU- CANASE ON HYPHAE OF BOTRYTIS CINEREA. Giovanni Arras*, S. Arru and V. Astone. *Istituto per la Fisiologia della Maturazione e della Conservazione del Frutto delle Specie Arboree Mediterranee, Via dei Mille 48, I-07100 Sassari, Italy. Fax: +39.079.232047; e-mail: G.Arras@imfpp.ss.cnr.it This study was undertaken to evaluate the inhibitory activity of several antagonistic yeasts and to characterise the mode of ac- tion of Candida oleophila (13L) against Botrytis cinerea. Yeasts C. oleophila 13L, Rhodotorula minuta 7L and Pichia guilliermondii 5A showed inhibitory values ranging between 87 and 100% on mandarin fruits. According to scanning electron microscope ob- servations, yeast 13L colonised the exocarp of the fruit, the wounds and the hyphae of B. cinerea, causing alterations to the cell wall of the latter. In vitro C. oleophila 13L degraded laminar- in and B. cinerea cell walls, more effectively than R. minuta 7L and Pichia guilliermondii 5A. A fragment of the β-1,3-glucanase gene was amplified by PCR, using primers selected on the basis of the β-1,3-glucanase from Candida albicans. 13L did not reveal any amplicons, which suggests deep differences in the genic sequence of the two micro-organisms. The results could indicate the pres- ence of peculiar features of 13L, which would make this micro- organism an ideal antagonist to control postharvest microbial fruit alterations. CELL POLAR LIPID (PL) FATTY ACIDS WITH HIGH PRESENCE OF PSEUDOMONAS SYRINGAE PV. TOMA- TO IN THE PHYLLOSPHERE AND IN THE RHIZOS- PHERE OF TOMATO PLANTS. Giorgio Mariano Balestra*, M. Antonelli, A. Fabi and L. Varvaro. *Dipartimento di Pro- tezione delle Piante, Università della Tuscia di Viterbo, Via S. Camillo De Lellis, I-01100 Viterbo, Italy. Bacterial tomato speck caused by Pseudomonas syringae pv. tomato (Okabe) Young et al. is one of the main diseases of toma- to. The bacterium is able to survive and multiply at an epiphytic level on the host and to live in the soil where tomatoes are culti- vated. The aim of this study was to verify the effect of an organic cropping system on the presence of P. syringae pv. tomato in the phyllosphere and rhizosphere throughout the tomato vegetative season. When a conventional cropping system was used, P. sy- ringae pv. tomato survived on the tomato phylloplane for the en- tire vegetative cycle especially on plants fertilised with mineral compounds. With the organic cropping system the bacterium was occasionally recorded but with values lower than 10 3 cfu cm -2 leaf. The pathogen was not found in the rhizosphere in plots cul- tivated with organic methods. P. syringae pv. tomato presence was also low (10 1 -10 2 cfu g -1 soil) in conventional plots. Moreover, in the field cultivated with organic methods, a relevant microbial presence (10 6 cfu g -1 soil) was recorded with a high percentage of bacterial species known to be natural antagonists of the pathogen (e.g. P. fluorescens and Bacillus spp.). Biological aspects and the possible epidemiological implications are discussed. VARIABILITY OF CERCOSPORA BETICOLA POPULA- TION IN RELATION TO HOST RESISTANCE. Paola Batti- lani*, V. Rossi, G. Chiusa and L. Languasco. *Istituto di Ento- mologia e Patologia Vegetale, Università Cattolica S. Cuore, Via E. Parmense 84, I-29100 Piacenza, Italy. Fax:+39.0523.599254; e-mail: patolo@pc.unicatt.it Cercospora beticola has been widely studied to verify the exis- tence of races, in relation to possible interaction between races and sugarbeet resistance. Notwithstanding this, the problem is still debated. Several studies found differences in the morphology or ecology of the fungus, whereas other researches showed that isolates from different geographical areas caused different disease severity when artificially inoculated onto plants, but only in a few cases they demonstrated an interaction between isolate and culti- var. In the USA, 3 different races were described on differential varieties. In the present work, interaction between sugarbeet cul- tivar and location was studied, under the assumption that differ- ent pathogen populations exist in different areas. Two 3 year tri- als were carried out with several sugarbeet genotypes, showing different resistance ratings, in several locations in the Mediter- ranean area. The results showed that the rating of the genotypes was not significantly influenced by location. Fungal isolates were collected in several countries and characterised for ecological and nutrimental needs, for toxin production, for genetic characters (by RAPD) and for several aspects of pathogenicity. The results confirmed the variability between C. beticola populations isolated from different areas. Therefore, variability of C. beticola popula- tions does not significantly influence the rating of resistant geno- types. Edizioni ETS Pisa, 1999 14 ABSTRACT XP 99 (227) 21-09-2004 10:08 Pagina 227