First Record of Cercospora Leaf Spot Disease on Okra Plants and its Control in Egypt

摘要

During June to September 2008, okra plants (Hibiscus esculentus L.) in Kafr El-Sheikh Governorate exhibited typical symptoms of Cercospora Leaf Spot (CLS) at different locations. Symptoms of infected okra leaves firstly started as light brown spots then turned to purple and varying in size. The spots spread to cover large areas of infected leaves. In case of severe infection, spots joined together and formed patches. Later, leaves were dry and remained intact with stem of plant. Samples of diseased leaves were collected to isolate the causal organisms. Isolated fungi were purified using single spore culture technique. Developed fungus was identified as Cercospora sp. Fresen based on cultural and morphological characteristics after light microscope examination. Also, Alternaria alternate and Aspergillus niger were isolated as associated fungi. Pathogenicity test confirmed efficiency of Cercospora sp. to induce typical symptoms on okra plants compared with other fungi. Foliar application using different concentrations of Topsin M-70WP and lemongrass oil was significantly reduced disease incidence compared with control. According to the available literature, this is the first record of CLS on okra in Egypt under natural infection in the field.