Phoma spp. are causal agent of white leaf spot disease of ginger in Indonesia

Abstract

Leaf spot disease is a serious constraint on ginger cultivation in Indonesia. The disease is primarily caused by certain fungal species. Another species of fungus that has never been reported before in Indonesia was consistently isolated from the collected samples of whitish spot symptom from Bogor and Sukabumi, West Java. The present study is aimed to determine the fungal identity and confirmed its pathogenicity as well as exploring its characteristics. Leaf tissue isolation, morphological characteristic observation and molecular analysis for determining the fungal identity, a pathogenicity test, disease occurrence observation on red- and white-ginger, colony characteristic on four different media and its response on PDA medium amanded with 0 - 500 ppm of mancozeb or copper hydroxide had been carried out in the plant pathology laboratory of ISMCRI in Bogor. The fungus was identified as a group of Phoma based on morphological characteristic, homology and phylogeny analysis. The carrot agar medium is the best medium for growing and sporulation of the fungus. The disease incidence and severity occurrence were more severe on white-ginger than the red-one. Mancozeb inhibited the fungus growth more effectively than copper hydroxide, but 500 ppm is not inhibiting the fungal growth.