SITARAMAIAH, KPARVATHI DEVI, G2016-08-182016-08-181989http://krishikosh.egranth.ac.in/handle/1/72881Sclerotia! wilt fungus Sclerotium rolfsii Sacc. and Fusarium decline disease fungus Fusarium solani (Mart).Sacc. were ·isolated in pure culture from diseased betelvine plants in Ponnur betelvine growing gardens. Pathogenicity tests with S.rolfsii had revealed that soil substitution method was effective in proving pathogenicity. However, introduction of inoculum through plastic tubes inserted at the time of planting was also effective, but the manifestation of wilt symptoms was delayed. Pathogenicity tests conducted with .F.. .solani indicated that immersing the clipped roots in !•solani inoculum for 24 h was very effective in p~oducing typical Fusarium wilt symptoms in soil and in hydroponics, similar to those observed under field conditions. Field survey of second year betelvine gardens (both in apparently healthy as well as Fusarium decline diseased gardens) was conducted in Po~nur betelvr.ne gardens, Guntur district (A.P) at 9 days interval, to correlate the per cent change in decline disease incidence with physical, and chemical properties of soil. The per cent decline disease incidence could be correlated with content of soil samples in the diseased ga~dens. bilogical change in magnesium As the magnesium content increased, the per cent change in decline disease incidence increased. Higher number of soil microflora (total fungi, total bacteria, total actinomycetes) are observed in diseased gardens and could be correlated with per cent change in decline disease incidence. As the soil microflora increased, the per cent change in decline disease incidence increased. The population of root-knot nematode Meloidogyne incognita was correlated with per cent change in decline disease incidence in diseased gardens. As the ~ •. incognita population increased, the per cent change in decline disease incidence increased. Interaction studies in pot culture experiments with M.incognita alone and in combination with s.rolfsii at different inoculum levels, indicated that maximum reduction in fresh shoot and root weight, dry shoot and root ~eight, shoot and root length was observed when the plants were inoculated with 4000 2nd stage juveniles of M.incognita & S.rolfsii simultaneously. Trichoderma harzianum was a potent antagonistic fungus .~gainst -S.rolfsii and -F.solani. This antagonistic fungus can be used in field plots to control S.rolfsii or F.solani. Thirteen betelvine cultivars collected from different states were tested for their resistance against S.rolfsii in pot culture. Cultivar "Karapaku" from Andhra Pradesh recorded 80% sclerotial infection. The cultivars Bangla Penna patna (Orissa), Tellaku (Ponnur-R) (Andhra Pradesh), Tellaku (Ponnur-S)· (Andhra Pradesh), Gachipan (Assam), Maghi (Bihar) and Kapoori (Bihar) gave 90% infection. However the remaining cultivars; Meetha cum Bangla (Uttar Pradesh), Bangla Desi (Uttar Pradesh), Bangla Nagaram (Uttar Pradesh), Kakair (Bihar), Godibangla (Ori'ssa) and Bangla (Madhya Pradesh) recorded 100% infection.enSTUDIES, SCLEROTIAL, WILT, FUSARIUM, DECLINE, DISEASE, BETELVINE, PONNUR, GUNTUR, ANDHRA PRADESHThesis