Role of some fungicides and essential plant oils on management of snap bean rust in Libya

Abstract

Significant reduction to the germinated urediniospores of Uromyces apendeculatus, the causal of bean rust disease, was occurred by the fungicides Dithane M-45, Kocide-2000, Sumi-8 and Topas as well as the essential oils of citronella, clove and thyme in vitro. Moreover, the tested fungicides resulted the highest inhibitory effect to the germinated urediniospores of the causal fungus than the tested essential plant oils. The inhibitory effect of the tested fungicides ranged between 14.2-34.9% and efficiency ranged between 64.3-85.1% , while in case of the essential plant oils ranged between 17.1-19.8 % and efficiency ranged between 79.4-82.0% . Topas fungicide was the most efficient one in this regard (85.1%), followed by Sumi-8 (84.1%) then cove oil (82.1%). Meanwhile, DithaneM-45 was the lowest efficient one (64.3%), followed by Kocide-2000 (66.3%). Greenhouse experiment revealed that spraying of snap bean plants with the tested fungicides and essential plant oils, three days before or after inoculation with the urediniospores of the causal fungus led to a significant reduction to severity of the disease with a significant increase to the produced green pods yield compared with the control. The most efficient treatments in reducing the severity of the infection with the disease and increasing the number of the produced pods and their weight plant-1 were Topas fungicide and clove oil when compared with the other treatments. Meantime spraying of fungicides two sprays firstly then spraying the essential oils another two sprays was anyofthetestedfungicidesandtheessentialplantoilsalone ledtoalowefficiency and produced low green pods yield . Meanwhile, the alternation of spraying the tested of highefficacyinloweringthediseaseandincreasingtheproducedgreen podsyield nearbytheefficiencyof bothSumi-8andTopasfungicides,eachalone. Noticeable increase the total phenolic compounds in the leaves of snap bean and the percentages of nitrogen and protein content in the green bean pods of the sprayed plants by the tested fungicides and essential plant oils was occurred compared with the control treatment.