Cucumber target leaf spot, caused by Corynespora cassiicola, is an emerging disease with a high incidence that causes severe damage to cucumbers on a global scale. Therefore, efforts need to be undertaken to limit the spread and infection of this pathogen, preferably by using environmentally friendly methods. In this study, the effects of temperature and moisture on the sporulation of C. cassiicola were investigated in vitro and in vivo. The novelty of our study refers to the observation of spore production and size as well as the revelation of a correlation between spore size and virulence. On potato dextrose agar (PDA) and cucumber−leaf extract agar (CEA), temperature played a critical role in spore production, which was strongly influenced by both temperature and moisture on detached leaves and cucumber seedlings. Maximum spore production was found at 30 °C on PDA and 25 °C on CEA, cucumber detached leaves and living plants. Lower spore productions were observed with a stepwise change of 5 °C. In addition, the largest spore production was found at 100% relative humidity (RH) in comparison to the other tested moisture. Moreover, moisture was found to be the most important factor affecting spore size, accounting for 83.09–84.86% of the total variance in length and 44.72–73.10% of the total variance in width. The longest−narrowest spores were formed at 100% RH, and the shortest−widest spores were formed at 75% RH. Furthermore, the result showed that larger spores of C. cassiicola were more virulent and small spores were avirulent. Our findings will contribute to the development of new strategies for the effective alleviation and control of cucumber target leaf spot.

Ginger holds significant economic importance in both China and worldwide agriculture. Fungi from the family Plectosphaerellaceae are globally recognized as aggressive plant pathogens. However, the effects of Plectosphaerellaceae species on ginger have been poorly understood. In this research, we identified two novel Musidium species (M. shandongensis sp. nov. and M. zingiberis sp. nov.), one newly recorded species (Gibellulopsis serrae) and one new host record (Plectosphaerella cucumerina) from the rotten rhizomes and roots of ginger in Shandong Province, China, utilizing morphological observations combined with multilocus phylogenetic analysis of the 28S large subunit (LSU), internal transcribed spacer (ITS) region, and translation elongation factor 1-alpha (TEF1-α) gene, along with pathogenicity analyses. Key diagnostic features include M. shandongensis exhibiting abundant mycelium ropes and coils, M. zingiberis showing dark olivaceous colonies, G. serrae producing brown chlamydospores, and P. cucumerina displaying conspicuous guttulae conidia. Comparative analyses with closely related taxa were based on detailed morphological descriptions, illustrations, and phylogenetic analyses. Artificial inoculation of healthy ginger in vitro and in vivo assays caused characteristic symptoms, such as wilt, leaf yellowing, and rhizome necrosis, identical to those observed on naturally infected plants. Our findings broaden current knowledge on the diversity of Plectosphaerellaceae associated with ginger, revealing them as serious threats to ginger cultivation in China.

Viral diseases pose a serious threat to pumpkin cultivation, which is an important cucurbitaceous vegetable crop. Recently, multi-virus mixed infections in plants have been continuously detected and reported. However, studies on mixed virus infections in pumpkins are limited. Through metavirome and polymerase chain reaction (PCR) analysis, we found that pumpkins exhibiting severe viral symptoms were co-infected with squash leaf curl China virus and tomato leaf curl New Delhi virus. Transcriptome analysis revealed that 2927 genes were upregulated, and 2273 were downregulated in virus-infected pumpkin plants, compared to the gene expression in healthy pumpkin plants. Cluster analysis showed that the expression of genes related to RNA silencing and the salicylic acid resistance pathway was higher in virus-infected pumpkin plants than in healthy pumpkin plants. Furthermore, quantitative real-time PCR confirmed that the expression pattern of genes related to RNA silencing and the salicylic acid resistance pathway aligned with the transcriptome sequencing results. Our findings provide a reference for investigating the mechanism of mixed infections by these two viruses to aid in the prevention and control of viral diseases in pumpkins.