Studies on cercospora leaf spot diseases (cercospora spp) and evaluation of some groundnut (arachis hypogaea L.) genotypes against infection in Kadugli Area

Field survey was carried out during the cropping season 2006/2007 in the' main groundnut cultivated areas in the vicinity of Kadugli town namely, Kolba, Tillo and E1samma. Samples of 15 groundnut farms were selected randomly in cach site to assess the leaf spot disease prevalence and percentage of infection. The results of the field surveyed of the three sites in Kadugli area, revealed that leaf spot disease was available and prevailing in almost all at the three surveyed sites namely (Kolba, Morta and Elsamma). However, its prevalence was varying from site to another. In Kolba and Tillo sites the percentages of the disease prevalence was 90% and 85%, rcspectively, while, in Elsamma it was 100%. The fungus was isolated from infected groundnut leaves on potato dextrose agar (PDA), pure cultures of cach isolation were examined for its macroscopic and microscopic characteristics. The isolatcd fungi were identified Cercospora arachidicola and cercospora personata according to the methods used by Richard. (2003) and produced similar symptoms in artificial inoculation.Tebuconazole (Raxil) was used in-vitro to evaluate its efficacy to inhibit the growth of Cercospora aracnidicola isolates. The test concentrations of 1000. 800, 600, 400 and 200 ppm of tebuconazole used were inhibited the growth of C. aracnidicola isolated from infected groundnut leaves. While, the concentrations of 100 and 50 ppm of tebueonazole had no effect in the growth of the isolate of C.arachidicola .The inhibition % were 70, 65, 55, 45 and 40 % in 1000, 800, 600,400 and 200 ppm concentrations, respectively. The field experiment was conducted under rainfed conditions for two consecutive seasons 2006/2007 and 2007/2008 in South Kordofan State, 5 km south of kadugli town. Four groundnut genotypes Gibaish, Sodiry, Barberton and Balady were evaluated for their sensitivity to leaf spot diseases. The first three experimental genotypes were received from Elobied research station. Whereas local Balady genotype was obtained from kadugli market.The treatments were arranged in randomized complete block design (RCBD) with four replications. The soil was ploughed by the wide level disk harrow. The plot size was 3X5 square m. Spacing was 60cm between rows and 20cm with in rows. The results showed that the groundnut genotypes differed significantly in their levels of susceptibility to cercospora leaf spot disease. The groundnut genotypes Sodiry and Barberton recorded the highest disease incidence (93.24%, 91.89%, respectively), followed by Gibaish with 80.94 %, while, Balady genotype recorded the lowest disease incidence (62.81 %) and it is more or less moderately susceptible