Sur l’origine fongique des galles observées chez les Eucalyptus

Abstract

Objective: In the literature, the observed galls on the leaves and on the stems of Eucalyptus were attributed to Leptocybe invasa (gall wasp) and to the fungi of the Alternaria genus (A. tenuis). In this study, we have attempted to specify if the isolation of Alternaria from the observed symptoms may lead to the development of galls on the leaves of Eucalyptus sp. plants. Methodology and results: On Potato Sucrose Agar, isolations were done from the observed galls on Eucalyptus leaves. For the study of pathogenicity, artificial inoculations were performed with Alternaria tenuis on different species of Eucalyptus. The results of isolations showed the presence of Alternaria tenuis, foliar lesions and galls of older leaves can host Alternaria. However, the isolation was negative for red young gall. The inoculation of Eucalyptus seedlings with Alternaria tenuis isolated from infected leaves induces the formation of leaf lesions. The leaf area indices vary between 7.5 and 17.5%. All the developed lesions were sporulating. The development of galls was not observed. Conclusion and Application of results: Observed galls on the leaves and petioles of plants of Eucalyptus were not induced by Alternaria tenuis. On the other side, representatives of these fungi was able to induce lesions on leaves of Eucalyptus seedlings.