Activities Of The Extracts Of 5 Species Plants Against Phytopathogens

In this paper, the inhibitory effects of the alcohol extracts of 15 species plants on 9 pathogens were evaluated by mycelial growth rate method. The results showed that most extracts completely inhibited the mycelial growth of tested pathogens at the extracts concentration of 0.1g/ml. At the extracts concentration of 0.01g/ml, the inhibition of alcohol extract of both Helianthus anuus (root) was more than 70% on the mycelial growth of Ascochyta citrullina Smith, and more than 65% on Botrytis cinerea. The extract of Biota orientalis owned the widest antifungal spectrum among all extracts. The inhibition of this extract was more than 50% on the mycelial growth of 4 tested pathogens, and between 45% and 50% on other 3 tested pathogens. The inhibitory effects of the alcohol extracts of 15 species plants on Gloeosprium piperatum, B. cinerea, Fusarium graminearum, Colletotrichum gloeosporioides and C. dematium were evaluated by germination on slide glass. The results showed that the inhibitory rates of the alcohol extracts of Sabina chinensis cv. Kaizuca, B. orientalis and Sapindus mukorossi (episperm) to the conidia germination of C. dematium were 93.3% at the extracts concentration of 0.01g/ml.The effects of the 5 alcohol extracts against 4 plant diseases were studied with detached leaves. The results showed that the therapentic or protective efficacy of the alcohol extract of B. orientalis to B. cinerea was respectively 45.8% and 52.5% at the extracts concentration of 0.05g/ml. Similarly, the protective efficacy of the extract to Gloeosprium piperatum and Colletotrichum gloeosporioides was 51.4% and 56.7% respectively, and its therapentic efficacy to Sclerotinia sclerotiorum was 64.4%.The tissues of 5 species plants were extracted by petroleum ether, acetic ether, alcohol and deionized water in turn. Then antifungal activities of the extracts were assayed by method of mycelial growth rate and spore germination on slide glass. The results showed that the inhibitory rate of the alcohol extract of S. mukorossi (episperm) against the mycelial growth of Pyricularia grisea was 77.4% at the extracts concentration of 0.01g/ml. The germination inhibitory rates of acetic ether extracts of B. orientalis, S. chinensis and S. chinensis cv. Kaizuca to conidia of C. dematium were 96.8%, 97.8% and 98.9% respectively. Furthermore, the inhibitory rate of S. chinensis to conidia germination of F. graminearum was 88.9%.The joint action of the acetic ether extract of B. orientalis and carbendazim on B. cinerea and G. piperatum were determined by method of mycelial growth rate and spore germination. The results showed that synergism was observed in ratios of 5:5, 4:6 and 2:8 by the acetic ether extract of B. orientalis (20mg/ml) to carbendazim (0.05mg/ml), and synergic ratios (SR) was 2.62 at the ratio of 2:8 in suppression of mycelial growth of B. cinerea. Similarly, SR was 2.90 at the ratio of 2:8 by the acetic ether extract of B. orientalis (20mg/ml) to carbendazim (1μg/ml). Additive effect was determined in suppression of conidia germination of B. cinerea and G. piperatum.