10th INTERNATIONAL VERTICILLIUM SYMPOSIUM 16-20 ...

EFFECT OF GUANITO ON OLIVE PLANTLETS GROWTH ANDON THE INOCULUM DENSITY OF VERTICILLIUM DAHLIAEMICROSCLEROTIAM. D’ONGHIA 1 , T. YASEEN 1 , A. IPPOLITO 2 AND F. NIGRO 21 Centre International de Hautes Etudes Agronomiques Méditerranéennes(CIHEAM)/Mediterranean Agronomic Institute, Via Ceglie 9, 70010 Valenzano (BA), Italy;2 Dipartimento di Protezione delle Piante e Microbiologia Applicata, University of Bari, ViaAmendola 165/A, 70126 Bari-Italy. E-mail: donghia@iamb.itIn the last two decades Verticillium wilt of olive, caused by Verticillium dahliaeKleb., has occurred with increasing frequency and severity in most olive growingareas of the Mediterranean basin. The disease affects olive trees starting from thenursery and microsclerotia (MS) are critical factor in the epidemiology and control ofthe disease. Among the environmentally friendly alternatives to protect plantletsagainst V. dahliae infection, the use of organic amendments has received muchattention. In this study, The effect of Guanito bio-fertilizer on the inoculum densityof V. dahliae microsclerotia in organic growing medium, and on vegetativeparameters of olive plantlets was assessed. Trials were carried out either on 8-monthsold self-rooted and 18-months old grafted olive plantlets, cv Leccino. The organicgrowing medium was amended with different concentrations of Guanito (1%, 2%, and3%, v/v). Before plant transplanting into pots, growing medium was artificiallyinoculated with V. dahliae microsclerotia (60-70 MS g -1 ).A phytotoxic effect was observed on plantlets growing in medium amendedwith 2% and 3% of Guanito. At these bio-fertilizer concentrations V. dahliaemicrosclerotia were almost completely inactivated. These results were more evidenton grafted than on self-rooted plantlets. Conversely, plantlets growing in 1% Guanitoamendedmedium showed a higher plant height than those growing in the unamendedmedium. Moreover, the inoculum density of V. dahliae microsclerotia in the mediumamended with 1% Guanito was significantly lower than the unamended control.113