Effect and physiological response of fungicide controlling Zoysia japonica large patch

Large patch is a turf disease caused by Rhizoctonia solani, which is seriously harmful to Zoysia japonica ‘Lanyin No. Ⅲ’. In order to explore the control effect of fungicides on “large patch”, ‘Banner Maxx’ (156 g·L⁻¹ propiconazole), ‘Heritage’ (50% azoxystrobin), ‘Headway G’ (0.31% azoxystrobin + 0.75% propiconazole), and ‘Medallion TL’ (12% fludioxonil) were selected to determine the inhibitory effect of fungicides on the colony growth of R. solani ZS-1 and R. solani ZW54 using the mycelium growth rate method. The results showed that the four fungicides caused inhibition of R. solani to varying degrees, and inhibition of fungicide ‘Heritage’ on mycelial growth of R. solani, with EC₅₀ values below 1 mg·L⁻¹ being the highest. Fungicides were sprayed on Z. japonica with ‘Heritage’ and ‘Banner Maxx’, then inoculated with R. solani ZS-1 and R. solani ZW54 to observe the occurrence of large patches and the physiological effects on plants. Compared with spraying with sterile water, the large patch incidence in Z. japonica was significantly reduced after spraying the fungicide (P < 0.05). After the fungicide treatment, the relative water content, chlorophyll content, phenylalanine ammonia-lyase activity, chitinase activity, and β-1,3-glucanase activity of leaves were much higher than those of the control treatment, while the proline and malonate contents were considerably lower than those of the control treatment (P < 0.05). From the point of view of the resistance of R. solani, R. solani ZS-1 is considerably more resistant to fungicides than the ZW54 strain. To sum up the effects of fungicide treatment on the inhibitory rate of R. solani and the physiological effects of Z. japonica, the fungicide ‘Heritage’ has the best control effect on large patches with a control effect of over 43%. The results of this study can provide guidance for the prevention and control of R. solani and lay a foundation for improving the ornamental value of Z. japonica and its use in lawns.