PRASANNA KUMARI, VAMULYA, G2018-08-082018-08-082017http://krishikosh.egranth.ac.in/handle/1/5810063744D5442The present study on phylogenetic variation and fungicidal management of Cercospora abelmoschi Ell. and Ev. infecting okra was taken up in the Agricultural College, Bapatla during 2016-2017. Cercospora leaf spot was mainly observed on the lower surface of leaves in the form of sooty to dark olivaceous colour, indistinct or none, fruiting effuse, forming angular vein limited areas in dense patches of conidiophores and conidia. Cercospora infected leaves were collected during kharif 2016 from eight different okra growing villages in Guntur district, Andhra Pradesh which were used for in planta isolation of fungal DNA using universal primers ITS 1 and ITS 4. The 550 bp amplicon thus obtained was restricted with hexa cutters, EcoRI, BamHI and tetra cutter Taq1 to find variability among Cercospora isolates. EcoRI found two restriction sites in all isolates except the Yazali isolate while BamHI found single restriction site in all the isolates with length polymorphism in Yazali isolate. Taq1 restriction indicated a high degree of genetic diversity among the isolates and was represented by three different banding patterns while in three isolates there was no restriction sites. Dendrogram constructed from similarity coefficients showed that Yazali isolate seperated into a group upon digestion with EcoRI and BamHI. Taq1 digestion of Yazali isolate clustered with Thimmareddipalem isolate. The results revealed that, polymorphism existed among the Cercospora isolates collected from Guntur district. The changes in single nucleotide resulted in variation in restriction sites for the different restriction enzymes used. Among all the tested fungicides, trifloxystrobin + tebuconazole @ 0.1% showed significant reduction of the disease on both lower leaves (35.61%) and upper leaves (12.98%), leading to the significant increase in yield (101.75 q ha-1 ). However, highest benefit cost ratio was recorded with propiconazole @ 0.1% (3.62). Phenol content in lower leaves(1.58 mg g-1 ) and upper leaves (1.52 mg g-1 ), total protein content in lower (9.32 mg g-1 ) and upper leaves (9.23 mg g-1 ) were significantly higher in trifloxystrobin + tebuconazole @ 0.1% applied plants. Total sugar content in lower (12.33 mg g-1 ) and upper leaves (10.08 mg g-1 ) were low in trifloxystrobin + tebuconazole @ 0.1% treatment. The reduction in Chlorophyll a and chlorophyll b was observed to be lowest in lower leaf (1.15 and 1.06 mg g-1 respectively) and upper leaf (1.28 and 1.02 mg g-1 respectively) in trifloxystrobin + tebuconazole @ 0.1% sprayed plants. The reduction in the total chlorophyll content was relatively less in trifloxystrobin + tebuconazole @ 0.1% as compared to other treatments due to reduced disease intensity and thus maintaining greenness of the leaves. Significant negative correlation existed between disease severity and total phenols (-0.903), total proteins (-0.903), chlorophyll a (-0.901), chlorophyll b (-0.788), total chlorophyll (-0.856) while significant positive correlation existed between total sugars and disease severity (0.932). Significantly high positive correlation existed between proteins and phenols (0.862), total chlorophyll (0.889), chlorophyll a (0.844), chlorophyll b (0.868). Similarly, significant high positive correlation existed between phenols and total chlorophyll (0.854), chlorophyll a (0.803), chlorophyll b (0.839). Significantly high negative correlation between total sugars and phenols (-0.924), proteins (-0.836), chlorophyll a (-0.919), chlorophyll b (-0.838), total chlorophyll (-0.897) existed.en-USnullThesis