Management of Phytophthora Blight of Pigeonpea using Trichoderma asperellum and a Chemical Fungicide

摘要

Commercial formulations of mefenoxam + mancozeb (Ridomil Gold MZ 68 WG) and metalaxyl (Apron 35 SD) were highly inhibitory to mycelial growth of Phytophthora cajani in vitro. Effective dose (ED50) of both the fungicides for 50 per cent inhibition of mycelial growth was less than 0.30 and 0.40 ug a.i. ml"1 of culture medium, respectively. For both the fungicides, zoospore production was inhibited by 100 per cent at 5 ug a.i. ml"1. Efficacy of Trichoderma asperellum against growth of P. cajani tested and T. asperellum inhibited the growth by 80.52 per cent in vitro. The sensitivity of T. asperellum to mefenoxam + mancozeb at different concentrations was evaluated and the grown T. asperellum was tolerant up to 0.4 % concentrations. Further seed treatment with mefenoxam + mancozeb and combination of mefenoxam + mancozeb and bioagent (I! asperellum) significantly reduced the Phytophthora blight caused by P. cajani under greenhouse and field conditions in three pigeonpea cultivars (ICP 87119, ICP 8863 and ICP 7119) tested. The grain yield in ICP 87119, ICP 8863 and ICP 7119 for fungicide alone were 11.2, 10.8 and 7.0 q ha"1; for combination of fungicide and bioagent were 11.6, 10.4 and 7.1 q ha"1; for untreated control were 5.2, 4.8 and 1.1 q ha"1 respectively.