Peter, Deusdedit2026-05-262026-05-262002https://www.suaire.sua.ac.tz/handle/20.500.14820/7606Masters ThesesThis study was carried out to investigate the occurrence of Streptomyces antagonistic to plant pathogens in pathogen-infested soils. Soils were sampled from the Horticultural Unit of Sokoine University of Agriculture (SUA) and from Mlali in Morogoro district, Tanzania. Isolation of Streptomyces was done using starch-casein agar. Fungi were isolated using Potato Dextrose Agar (PDA) amended with Rose Bengal. Plant pathogenic fungi were identified using culture and microscopic characteristics. There were significant (p=0.05) differences in populations of Streptomyces in soils obtained from rhizosphere of different tomato varieties/lines with different disease severity levels. The populations were lowest in soils associated with tomato line 2 from Horticultural Unit and highest in soils of the other tomato varieties/lines. There were significant (p=0.05) differences in populations obtained from soils sampled under different disease severity. The populations of fungi showed significant (p=0.05) differences between the two locations, being lower at Mlali and higher at SUA Horticultural Unit. There were significant (p=0.05) differences in populations of fungi isolated under rhizospheres of tomato plants with varying levels of disease. Numbers of pathogenic fungi identified varied not only from one site to another but also one tomato variety/line to another, and also among different disease severity levels. About 73% of Streptomyces isolates produced antibiotic to various levels against plant pathogenic fungi which were identified as Phytopthora sp. 1 and 2, Aspergillus sp. 1 and 2, Phoma sp. 1 and 2, Pythium sp., Penicillium sp. And Botrytis sp. Other isolates (27.0% of all isolates) did not produce antibiotic against any of the tested plant pathogenic fungi.enStreptomycesSoil microorganisms-TanzaniaPlant pathogensPlant diseases-Biological controlDisease-suppressive soils-MorogoroAgricultural microbiology-TanzaniaSoil biology-Tanzania-MorogoroThesis