The effects of chemical inducers on soil borne fungal pathogens on Turfgrass

In this thesis, the effects of different concentrations of salicylic acid (SA), DL-β-amino-n-butyric acid (BABA) and acibenzolar-s-methyl (BION) on mycelial development of Rhizoctonia solani, Rhizoctonia cerealis and Fusarium graminearum in vitro and on disease severity in Lolium perenne (English ryegrass) in vivo. SA reduced the mycelial development of pathogens in increasing concentrations in solid media in vitro and completely inhibited at 700 ppm for R. solani, 300 ppm for R. cerealis and 1000 ppm for F. graminearum, respectively. In general, BABA and BION have reduced the mycelial development of pathogens with increased concentrations. However, different concentrations of BABA had no effect on mycelial development of R. cerealis in solid medium. The effects of SA, BABA and BION in vitro in liquid media were similar to those solid media. The effects of 3 different doses of SA (100, 300, 600 ppm), BABA and BION (100, 500, 1000 ppm) on the disease severity of R. solani, R. cerealis and F. graminearum were tested in vivo. SA has been more successful on Rhizoctonia species in reducing the disease severity. SA at 600 ppm dose decreased the severity of the disease by 98.5%, 96.3% and 51.0%, respectively. BABA decreased the disease severity of F. graminearum at the highest concentration by 94.6%. The effects of BION at 1000 ppm concentration on the disease severity of the three tested pathogens were similar and chemicals reduced the disease severity of pathogens by 86.2%, 83.7% and 85.2%, respectively. SA, BABA and BION have also increased grass yield beside with the disease-reducing effects. SA increased in grass yield by 71.0% and 76.3% respectively against Rhizoctonia species. The highest concentration of BABA and BION increased grass yield against F. graminearum by 92.9% and 71.1%, respectively. SA, BABA and BION have been shown to have beneficial effects against soil-borne pathogens in vitro and in vivo, and have shown potential use in control of diseases.