FURTHER STUDIES ON THE CONTROL OF "CARDONCELLO" MUSHROOM YELLOWING IN SOUTHERN ITALY.

Yellowing or bacteriosis is the most severe disease of Pleurotus eryngii (DC. : Fr.) Quél., the mushroom commonly called "cardoncello" that is particularly appreciated in Italy and in some foreign countries (Germany, Canada, etc.). Pseudomonas 'reactans' species complex, and P. tolaasii Paine, saprophytic bacteria inhabiting the mushroom hyphosphere, are reported, though with different importance, as the causal agents of the disease that sometimes causes huge losses to "cardoncello" cultivations. Control of the bacteriosis using white vinegar (6‰ acidity, pH 3.2), ozone (12-15 ppm) or 95.2 mM acetic acid was attempted. Two different cultivation cycles were carried out with P. eryngii strains "51" and "65" provided by Micotec (Gravina di Puglia, Italy) after incubation in standard substrate contained in thermoresistant polypropylene bags. The casing soil of each bag was inoculated with 10 ml of a suspension containing 1.7x10⁸ CFU ml^-1 of PR51 strain of P. 'reactans', previously isolated from "cardoncello" basidiomata affected by yellowing. Antibacterial treatments were carried out 13 times during the 43 days of each productive cycle. Substrate bags used as control were sprayed with tap water. For each bag, appearance and development of disease symptoms, ba-idioma shape and size, marketable mushroom yield and number of total bacteria, fluorescent Pseudomonads and total fungi presents in casing soil were recorded. Several basidiomata produced by control bags showed severe yellowing symptoms. Vinegar, ozone and acetic acid significantly prevented bacteriosis appearance and development and reduced the number of total bacteria, fluorescent Pseudomonads and total fungi present in casing soil of compost bags. [ABSTRACT FROM AUTHOR]