Fungicidal Efficacy Screening for Cobweb Disease Control

Referring to the fungicides with high efficacy and low toxicity used for the control of cobweb disease on other edible mushroom, we selected various fungicides, including Carvacrol (5% SL), Osthol (1% EW), Eugenol (0.3% SL), Propiconazole (25% EC), Triadimefon (20% EC), Trifloxystrobin and tebuconazole (75% WDG), Prochloraz-manganese chloride complex (50% WP), Pyraclostrobin (10% WDG) and Difenoconazole (10% WDG). Preliminary indoor screening of fungicides for prevention and control of cobweb disease agent on L. decastes: the test method was modified appropriately [51 ]. According to the active ingredients, nine kinds of low toxic fungicides were diluted with sterile water to make stock solutions of certain concentrations. In order to determine the concentration range of each fungicide, a pre-test was carried out with a concentration gradient of 5 times for each fungicide. According to the volume ratio, the PDA medium containing fungicide was prepared with the amount of storage fluid: PDA = 1:9 in a Petri dish with diameter of 9.0 cm. The pathogen filaments (2021062102-1) which were cultured and grown on PDA medium at 25 °C in dark for 4 days were made into cake with a 5 mm hole punch. PDA medium with equal amount of sterile water without fungicide was used as control. The fungus cakes were transferred into the prepared medium, and incubated at 24 °C in dark for 4 days. In this process, the growth of pathogen was observed to determine the initial concentration of each fungicide. Selecting the fungicide that could inhibit the pathogen and conduct further concentration screening test. According to the pretest results, each fungicide was diluted into 6 concentration gradients according to the effective components. The method of inoculation and culture for each treatment was the same as above. The diameter of colonies was measured with crossing method [18 ], when colonies in control almost covered the Petri dish. Inhibitory percentage on mycelia growth was calculated after treatment with different concentrations and fungicides. Inhibition of mycelial growth (%) = [(dimeter of mycelium in control -diameter of mycelium in treatment)/dimeter of mycelium in control]x100. Each treatment was repeated three times. The EC₅₀ value of each fungicide was evaluated by using ANOVA in three replicates. The ANOVA was performed as per Duncan’s multiple range test to determine the significant differences (* p < 0.05) [52 (link)].