First report of Fusarium fujikuroi causing brown leaf spot on kiwifruit.
Kiwifruit (Actinidia spp.) is native to China, and kiwifruit brown leaf spot (BLS) disease has become more severe as planting area has increased. The disease persists throughout the growing season and causes serious defoliation and fruit drop, adversely affecting fruit yield and quality as well as economic returns. In June 2018, symptoms of BLS were observed on kiwifruit cv. Taishan No.1 (Actinidia chinensis) in a farm in Shandong Province with a disease incidence of approximately 60.0%. Symptomatic small spots initially appeared at the middle or edges of leaves, enlarged irregularly, and developed into brown necrotic spots with dying curly edges. Based on the results of morphological observations, molecular investigations (sequence analysis of the RNA polymerase II subunit 1 gene, RNA polymerase II largest subunit gene and translation elongation factor-1 alpha regions) and pathogenicity tests, the causal agent was identified as F. fujikuroi. In New Zealand, F. acuminatum was reported to cause kiwifruit leaf spot. In China, Alternaria tenuissima, Botryosphaeria dothidea, Lasiodiplodia theobromae and Neofusicoccum parvum were reported as causal agents of BLS disease of kiwifruit foliage. This is thought to be the first report of F. fujikuroi causing BLS on kiwifruit worldwide.