Abstract

Proteas have been introduced as new commercial crops during the last decade in Chile. The area where these species are cultivated has increased during recent years and is located between the V and VII Regions (approximately 33° South latitude and 35° South latitude). However, insects and diseases which could affect them, decreasing productivity and quality, have not been described for our country. In order to get a better knowledge about the nature of microorganisms associated, samples were taken from plants showing symptoms that could be related with the presence of plant pathogens, with the aim to identify pathogenic fungi or bacteria. From the total of pathogens detected and identified, 86% were fungi and 14% were bacteria. Among fungi, we found the genera Phytophthora sp., Fusarium sp., Alternaria sp., Cladosporium sp., and Botrytis sp., all of them reported previously in other countries as pathogens that affect Proteaceae plants. In the case of pathogenic bacteria, it was possible to identify the presence of Pseudomonas sp., and Xanthomonas sp. The first one was found in the genera Protea, Leucadendron and Leucospermum, and the other in the Chilean native Proteaceae Gevuina avellana, as well as in Protea. Xanthomonas has not been reported previously affecting plants of this family. Considering that Fusarium was one of the widest spread pathogen, an assay was carried out, during the season 2003/2004, to evaluate Trichoderma harzianum as a biological prevention alternative. Different concentrations of this fungus (conidia suspensions) were applied as treatments, before inoculation with Fusarium sp. A commercial fungicide (benomyl) was used as control, including also two other treatments without applications, one inoculated with the pathogenic fungus, and the other inoculated with sterile water. Trichoderma reduced the incidence of Fusarium wilt, and the two highest concentrations tested (109 and 108 conidia/ml) did not differ statistically from benomyl.