RÉSUMÉ
Objective To control stem blight disease of Schizonepeta tenuifolia caused by Phytophthora nicotianae.Methods The antagonist effect of 13 Trichoderma strains(including T.viride and T.hamianum)was evaluated upon mycelia growth of P.nicotianae.Trichoderma strains with high antagonistic activities against the pathogen were used to control stem blight of S.tenuifolia in the field.Results Of 13 Trichoderma strains tested,T.viride strain M3 showed maximum mycelia growth inhibition(83.2%)to the pathogen,followed by T.viride strain Tv04-2(78.2%)and then T.harziamum strain ThB(65.0%),in vitro.Fungal cell wall degrading enzymes,protease,and β-1,3-glueanase were analyzed qualitatively and quantitatively in further study.T.viride strains M3,Tv04-2,and T.harzianum strain ThB efficiently against P.nicotianae were used to control stem blight of S.tenuifolia in the field,and T.viride strain M3 showed the best biocontrol potential.Conclusion Trichoderma spp.can be used as alternatives of pesticides to control stem blight,one of the serious soilhome diseases of S.tenuifolia caused by P.nicotianae.However,though T.viride strains Tv04-2 aad T.harzianum strain ThB are also highly against P.nicotianae in vitro,the controlling efficacy of them on stem blight disease is not as excellent as T.viride strains M3 in the field.
RÉSUMÉ
Antagonistic mechanisms of Trichoderma viride M3, Tv04-2, and T. harzianum ThB, were studied against Phytophthora nicotianae, the pathogen of stem blight disease on Schizonepeta tenuifolia by dual-culture, hydrolase activity, volatile and nonvolatile substances. Results indicated that competitive, mycoparasitism and antagonism were the antagonistic mechanisms of three Trichoderma spp. against P. nicotianae. Hydrolase activity showed that M3 was the highest for beta-1, 3-glucanases activity while ThB was the highest for proteases activity among the three T. strains, and they could produce volatile and non-volatile substances, also.