Browsing by Author "Debebe Ephrem"

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    Investigations on the Effect of Trichoderma. Viride and Pseudomonas Fluorescens against Late Blight of Potato (Solanum Tuberosum) Under Greenhouse Conditions
    (Addis Ababa University, 2005-07) Debebe Ephrem; Amutha R (Professor)
    Late blight caused by the oomycete pathogen, Phytophthora infestans (Mont.) de Bary, is the most devastating disease of potal.) throughout the world including Ethiopia. The disease is usually controlled by I epeated applications of chemical fungicides. The serious pollution problems a~sociated with the use of chemicals and the development of resistance to the available fungicides by new and more aggressive P. infestans strains urge us to have alternative control strategies such as biological control. Trichoderma viride-TNAU and Pseudomonas f1uorescensBak150 were tested for their efficacy in controlling the pathogen in vitro and in greenhouse. In vi!m a!1tagonism test ber.vcen ;. vir!de and P. !nfestans showed a radial growth inhibition of the pathogen by 36.7% followed by a complete overgrowth of T. viride on P. infestans. P. f1U1;Jr.e!$c.ef/$ inhibited the radia! growth· . of the pathogen by 88%. Foliar spray methqcj·, l'lSe)d' in (tire ' gre:enhb~~~: ,tri61:: :": involved foliar spraying of the plants with s~sp~~sio~s' '',lUh .T.:vi~id~: (2)';:<. , c' _.: .,,:,.' I' I , f1uorescens, (3) mixed culture of the two antagonbtka~d: (4'i,9lrerilic:ql, f4nbiJidp,,: ) ;:'., - ,1 r. • I '. • mancozeb followed by spraying the pathogen three: .d~yh, la(M. Pe!"cBht~g;s,lE)af area infection was measured every week and area 'uhMr'the disease 'pro'gress . curve (AUDPC) was calculated and compared among the treatments. The result showed that T. viride (AUDPC=260) and P. fluorescens (AUDPC=765.1) significantly (PO.05) in the disease severity (AUDPC) among each of the treated ones and the inoculated/untreated controls. Thus, neither the bioagents nor the chemical fungicide was able to control or suppress the transmission of the pathogen from the infected tubers to the emerging sprouts and the subsequent progress of the disease.