Phylogeny, Morphology, Epidemiology, and Control Strategies for Plurivorosphaerella nawae, the Causal Agent of Circular Leaf Spot in Persimmon

Circular leaf spot (CLS), caused by the ascomycetous fungus Plurivorosphaerella nawae Hassan & T. Chang, comb. nov. (formerly Mycosphaerella nawae), is a significant disease affecting persimmons worldwide. Phylogenetic and morphological analyses have led to the reclassification of M. nawae, now placed in the newly established holomorphic genus Plurivorosphaerella within the Mycosphaerellaceae family. Seasonal monitoring showed that the release of P. nawae ascospores from pseudothecia occurred between May and September, peaking from mid-June to mid-July. A strong correlation was observed between water - dispersed ascospores and cumulative rainfall. Disease symptoms first appeared in late August, with the highest disease incidence recorded in mid-October. Infected leaves showed significantly higher levels of phenolic compounds, vitamin C, and antioxidant activity compared to healthy older leaves and the unaffected portions of infected leaves. These elevated levels in younger leaves may contribute to resistance against CLS. The accumulation of phenolic compounds and antioxidants in infected leaves appears to be part of a post-infection response, marking an early defense mechanism in persimmons. A fungicide application program involving the sequential use of trifloxystrobin, difenoconazole + fluazinam, trifloxystrobin + tebuconazole, mancozeb, and mancozeb + myclobutanil at 15-day intervals, beginning in late June, was highly effective in controlling CLS.