Evaluation and Control of Alternaria tenuissima Causing Leaf Spots in Blue Honeysuckle in China

Abstract

Blue honeysuckle is emerging as a popular edible fruit and folk medicine. However, from June to August 2021, a serious leaf-spot disease affected the yield and quality of blue honeysuckle in Harbin, Heilongjiang Province, China; the species and characteristics of the pathogens responsible for the disease are unknown. In this study, 30 fungal isolates were obtained from infected blue honeysuckle leaves, identified as Alternaria tenuissima based on morphological and molecular characteristics and phylogenetic analyses. To the best of our knowledge, this is one of the first studies to identify A. tenuissima as the causal agent of blue honeysuckle leaf spots in China. Pathogenicity tests of the isolates revealed that most isolates exhibited moderately pathogenic. All blue honeysuckle cultivars tested were found to be susceptible to 30 A. tenuissima isolates. In addition, elder, Dahurian rose fruit, sea-buckthorn, rowan, hawthorn, bird cherry, and sorb could be infected by A. tenuissima isolates, while European cranberry bush and nanking cherry were not infected. A. tenuissima isolates were highly sensitive to prochloraz (EC50 ≤ 0.50 μg·ml–1) with 86.21% efficacy at 400 μg·ml–1 in the field trials. Therefore, the application of rotation and chemical fungicides are considered to control the disease-causing leaf spots in blue honeysuckle. These results provide a basis for controlling A. tenuissima in blue honeysuckle in China.

A Novel Strain of Fusarium oxysporum Virus 1 Isolated from Fusarium oxysporum f. sp. niveum Strain X-GS16 Influences Phenotypes of F. oxysporum Strain HB-TS-YT-1hyg

“…Difenoconazole, a demethylation inhibitor (DMI) fungicide, has been widely utilized to control black spot disease caused by Alternaria [50,51], as well as Fusarium wilt incited by F. oxysporum [52,53]. Prochloraz is also a DMI fungicide, which is used to manage spot disease caused by A. tenuissima [54] and the Fusarium head blight incited by F. graminearum [55] or Fusarium wilt induced by F. oxysporum [53]. Pydiflumetofen, as a succinate dehydrogenase inhibitor (SDHI) fungicide, can effectively control Alternaria leaf spot caused by A. alternata [56] and Fusarium wilt incited by F. oxysporum f. sp.…”