Isolation and characterization of the fungus Alternaria alternata , the causative agent of leaf-spot disease, from some vegetable crops
College Of Basic Education Researches Journal,
2014, Volume 13, Issue 2, Pages 923-934
AbstractTwenty five isolates of the fungus Alternaria alternata, the causative agent of leaf-spot disease, were obtained from diseased specimens of eight vegetable plants collected from several sites within the city of Mosul, Iraq. The isolates were purified by the slide-culture technique and the single-spore isolation technique and used to compare their radial growth rate and efficiency in producing conidia, both features are essential for successful spread of the plant pathogen.After 5 days incubation on PSA at (25±1)ºc isolate AA4 from Beta vulgaris gave the largest colony diameter (55mm) while isolate AA11 isolated from Raphanus oleracea gave the smallest (34.1mm).As regard the conidial suspension density, isolate AA20 from Abelmoschus esculentus gave the most dense suspension (14x105 conidia/ml) while isolate AA24 from Beta vulgaris gave the least dense suspension (8.2x105 conidia/ml) among all isolates. Both of these attributes are genetically controlled and very essential for successful spread of the pathogen.
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