Walnut (Juglans regia L.) root rot (Rhizoctonia solani Kühn) and coal rot (Macrophomina phaseolina Goid.) in beans with green barkextract and synthetic juglon

In this study, the effect of walnut (Juglans regia L.) green bark extract (WGBE) and synthetic juglon (SJ), which is known to have a toxic effect on fungi thanks to the phenolic substances it contains, especially juglone, on significant root rot (Rhizoctonia solani AG-4) and coal rot (Macrophomina phaseolina) in beans was investigated. Thus, it is aimed to contribute to the use of natural preparations that can be an alternative to pesticides in the fight against plant diseases formed by the pathogens in question, and to the development of methods sensitive to human health and the environment. In the study, plant extracts were obtained from walnut green bark with the help of ethanol. It was examined whether the factors of WGBE and SJ had anti-development or lethal effects on R. solani and M. phaseolina. For this purpose, in the laboratory environment, two fungi (R. solani AG-4 and M. phaseolina), which are primarily plant pathogens, developed in Petri containers. For WGBE; 0% (pure water/negative control), 2%, 4%, 8%, 16% and 32% and Captan 50 (2.5 g/l) effective substance fungicide (positive control); for SJ, 0% (pure water/negative control), 0.2%, 0.4%, 0.8%, 1.6% and 3.2% g/l and Captan 50 (2.5 g/l) effective fungicide (positive control) were applied to bean plants infected in pots under climate chamber conditions. Evaluations were made by looking at the age and dry weights of the above-ground and root parts in the plant, root length, number of flowerings, number of fruits (pods) and severity of the disease. According to the results obtained in petri dishes, it completely prevented the development of the pathogen at the rates of 4% and above WGBE; and 1.6% and above of SJ. In potting studies, WGBE gradually reduced the disease severity of both pathogens in the plant after a 2% dose. However, doses after 8% of WGBE showed a phytotoxic effect on beans, and as the dose increased, the phytotoxic effect gradually increased. While 8% and subsequent doses of SJ had an effect against root rot, none of the doses affect coal rot disease. No phytotoxide was found in beans in any dose of SJ. As a result, WGBE was found to be more successful than SJ in the prevention of both fungal diseases in beans. However, when evaluated in terms of not developing phytooxide, the doses between 2-4% of the WGBE should be preferred.