GUPTA, A.K.RANDEEP, SINGH2017-01-042017-01-04201247856http://krishikosh.egranth.ac.in/handle/1/94355ABSTRACT The present investigation on “Colonization of native Agrobacterium radiobacter isolate in relation to control of crown gall in stone fruit nurseries” was carried out to study colonization and persistence of agrocin producing A. radiobacter isolate (s) in rhizosphere soil of bitter almond and cherry rootstock Colt plants applied as seed and root dip vis-a-vis its effect on incidence of crown gall, and compatibility of A. radiobacter isolate (s) with recommended pesticides. Mutants of A. radiobacter isolate Cherry 2E-2-2 and strain K84 resistant to rifampicin (2500 ppm) and A, tumefaciens isolate Peach 2E-1-3 and strain C58 resistant to streptomycin (2500 ppm) were developed to study their population during the growth period applied as seed and root dip treatments on bitter almond (behmi) and cherry rootstock Colt, respectively. Maximum population (294x 106 cfu/ g of soil) of A. radiobacter isolate Cherry 2E-2-2 applied as seed treatment on behmi was observed followed by 284 ( x 106 ) cfu/ g of soil in the same isolate applied as root dip on cherry rootstock Colt after 9 months at the time of uprooting of plants as compared to 187 ( x 106 ) cfu/ g of soil in strain K84 applied as seed treatment on behmi and 242.30 ( x 106 ) cfu/ g of soil applied as root dip on Colt in the same strain. The recommended doses of different pesticides viz., chlorpyriphos (0.15%), carbendazim (0.05%), glyphosate (0.1%), atrazine (0.5%), oxyfluorfen (0.05%), phorate (0.05%) and carbofuran (0.05%) resulted in 19.00, 10.45, 22.34, 20.68, 6.70, 17.26 and 12.49 per cent inhibition, respectively. Mancozeb at 0.25 and 0.3 per cent resulted in 35.06 and 43.88 per cent inhibition in the growth of A. radiobacter isolate Cherry 2E-2-2. Copper oxychloride at all three tested concentrations (0.2, 0.25 and 0.3%) completely inhibited the growth of native A. radiobacter isolate Cherry 2E-2-2. These results indicate that in stone fruit nurseries, chlorpyriphos, carbendazim, glyphosate, atrazine, oxyfluorfen, phorate and carbofuran at recommended doses can be applied after the application of A.radiobacter.enThesis