Investigation of chemical and biological control possibilities of stem canker and black scurf (Rhizoctonia solani) diseases in potatoes

Abstract

Aims: In this study, it was aimed to determine the effects of various chemical fungicides, plant activators and biological preparats on the suppression of mycelial growth and disease incidence caused by stem canker and black scurf pathogen Rhizoctonia solani. Methods and Results: In the experiment, the effects of fungicides (flutolanil, fluxapyroxad, fludioxonil, penflufen+Prothiconazole and tolclophos-methyl+thiram) and plant activators (ISR-2000, Crop-set, Aliette and Messenger Gold) on the mycelial growth of R. solani were determined under laboratory conditions. The antagonistic effects of biological preparats (T-22 Planter Box, Trianum-p, Serenade and Cedriks) against R. solani were also investigated. The effects of chemicals and biological preparats on the disease of R. solani were evaluated with micro-plot trials. According to the in vitro results; fungicides tolclophos-methyl+thiram and flutolanil inhibited mycelial growth 100% from 5 ppm. Among plant activators, the highest fungicidal effect was caused in Aliette with 31.5% inhibition at 1000 ppm. Commercial bio-fungal preparat Trichoderma harzianum, suppressed mycelial growth at varying rates between 3.8% and 66.9%. Commercial bio-bacterial preparats, Pseudomonas fluorescens (Cedriks) and Bacillus subtilis (Serenade) inhibited mycelial growth by 82.9% and 59.4% respectively. According to the results of micro plot experiments, the most successful treatments were determined as tolclophos-methyl+thiram, fosetyl-al and P. fluorescens. Conclusions: Among tested treatments, Tolclophos-methyl+thiram, fosetyl-Al and P. fluorescens treatments significantly suppressed the growth of R. solani both in vitro and in vivo. Significance and Impact of the Study: Although fungicides were found to be quite effective in laboratory conditions, they showed similar fungicidal effect as shown by plant activators and biological preparats in field conditions. Considering this effect, it is possible to say that plant activators and biological preparats may have potential as an alternative control method to registered fungicides.