Fusarium diseases, including corn root rot, sheath rot, stalk rot, and ear rot are frequently occurring in maize producing areas of China. Fusarium stalk rot and ear rot are the most serious diseases and often occur at the same time, but it is unclear whether there is a correlation between Fusarium composition and disease occurrence. This study was conducted to clarify the relationship between the two diseases. A total of 49 corn stalk rot samples were collected from 15 regions of eight provinces in China from 2016 to 2018. The pathogens were isolated and identified separately from stalks, ear stems, and kernels. The contents of the fumonisins (FB₁ and FB₂) were detected in kernels. The results showed that the main Fusarium species were found in corn kernels, ear stems and stalks at the same time. The results showed that 1201 strains of Fusarium verticillioides, 668 strains of Fusarium oxysporum, 574 strains of Fusarium graminearum species complex (FGSC), 318 strains of Fusarium equiseti, 95 strains of Fusarium proliferatum, and 40 strains of Fusarium subglutinans were isolated from 1470 corn kernels, 245 ear stems, and 1225 stalks randomly selected from 49 samples. The contamination rate of fumonisins in the 49 samples was 57.1% with an average content of 1.9 μg/g, of which four samples exhibited higher levels as set by the European Commission (4.0 μg/g). These results provide a certain association between stalk rot and ear rot and lay a foundation to study the relationships among Fusarium maize diseases.

Abelmoschus manihot (Linn. ) Medicus (A. manihot) is an annual to perennial herb of the Malvaceae okra, mainly distributed in Guangdong, Guangxi, Fujian, Hunan, Hubei provinces. It can not only be used as an ornamental flower, but also has important economic and medicinal value. Last year, 10% A. manihot in 1,000 acres were observed with stalk rot in the Zhongshang Agricultural Industrial Park, 50 meters east of Provincial Highway 235 in Gaoyang County of Hebei province. Internal discoloration of the stem began brown to black discoloration of the vascular system and became hollow, with the mycelium growing on the surface. Stems from symptomatic plants (approximately 5 mm2) were dissected, washed free of soil, then soaked in 75% ethanol for 16 s to surface-sterilize, and 40 s in HgCl2, then rinsed three times in sterile water. After being dried with blotting paper, five pieces were placed on potato dextrose agar (PDA). After cultured 2 or 3 days, five isolates were purified and re-cultured on PDA in the dark at 25°C. The color of the colony was white. The hyphae were radial in PDA, and the aerial hyphae were flocculent, well-developed with luxuriant branches. The colonies were white and floccus, and the aerial hyphae were well developed, branched and without septum on corn meal agar (CMA). The sporangia were large or petal shaped, composed of irregular hyphae, terminal or intermediate , with the size of (31.6-88.4) μm ×(12.7- 14.6) μm. Vesicles were spherical, terminal or intermediate, ranging from 14.6 to 18.5μm. Oogonia were globose, terminal and smooth which stipe was straight. Antheridia were clavate or baggy and mostly intercalary, sometimes terminal. Oospores were aplerotic, 21.5 to 30.0 μm in diameter, 1.6 to 3.1 μm in wall thickness. The isolates morphological characteristics were consistent with P. aphanidermatum (van der Plaats-Niterink 1981, Wu et al. 2021 ). To identify the isolates, universal primers ITS1/ITS4 (White et al. 1993) were used for polymerase chain reaction–based molecular identification. The amplification region was sequenced by Sangon Biotech (Shanghai, China) and submitted to GenBank (MW819983). BLAST analysis showed that the sequence was 100% identical to Pythium aphanidermatum. Pathogenicity tests were conducted 3 times, with 4 treatments and 2 controls each time. The plants treated were 6 months old. Then the hyphae growing on PDA for 7 days were cut into four pieces. Next, they were inoculated into the soil of the A. manihot. Negative control was inoculated only with PDA for 7 days ( Zhang et al. 2000). The plants were then placed in a greenhouse under 28°C, 90% relative humidity. After inoculated 20 to 30 days, the infected plants showed stalk rot, the same symptoms as observed on the original plants. The control plants didn’t display symptoms. Pythium aphanidermatum was re-isolated from infected stems and showed the same characteristics as described above and was identical in appearance to the isolates used to inoculate the plants. To our knowledge, this is the first report of Pythium aphanidermatum infecting A. manihot stem and causing stalk rot in China. It may become a significant problem for A. manihot. Preliminary management practices are needed for reducing the cost and losses of production.

The increased use of chlorantraniliprole and fludioxonil has sparked concerns about their residues and impact on the soil microbiome, highlighting an urgent issue requiring attention. This study investigates the residue dynamics of corn after chlorantraniliprole and fludioxonil treatments, as well as their effects on soil enzyme activity and microbial community structure. High-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) analysis showed a significant decrease in chlorantraniliprole and fludioxonil residues in the soil after combined application, especially with chlorantraniliprole. This application caused a temporary reduction in urease and sucrase activities. Furthermore, high-throughput sequencing of the soil microbiome revealed a decrease in the relative abundance of Talaromyces during fludioxonil application, while Mortierela and Gibberella increased. Additionally, Vicianmibacteraceae and Vicianminbactererales saw significant increases after chlorantraniliprole application. The combined application of chlorantraniliprole and fludioxonil not only decreased the population of harmful microorganisms but also lowered residue levels in the soil when compared to individual applications. This ultimately enhanced the efficacy of control measures and promoted environmental compatibility.

Northern corn leaf blight (NCLB), caused by Setosphaeria turcica (S. turcica), is one of the devastating foliar diseases of maize (Zea mays) in maize-producing regions globally. Previous research has predominantly centered on elucidating the infection strategy and process of the pathogen, but the molecular mechanism of maize response to the pathogen is still largely unknown. In this study, we employed transcriptomics technology to comprehensively analyze alterations in RNA expression profiles within maize leaves at critical time points (hours post-infestation, 24 hpi, and 72 hpi) during S. turcica infection. Our study identified 7196 differentially expressed genes (DEGs) involved in the maize leaf response to S. turcica infection compared to the control (CK at 0 hpi). Functional analysis revealed that these DEGs were enriched in multiple metabolic pathways. Notably, genes associated with “benzoxazinone biosynthesis”, “tetracyclic pyrrole biosynthesis”, and “photosynthesis” were all down-regulated. In contrast, DEGs related to “phenol metabolism” and “phenylpropanoid metabolism” were significantly upregulated. Moreover, the genes belonging to the NAC, MYB-related, HB, and WRKY transcription factor families were also significantly enriched among the DEGs. The expression levels of six randomly selected DEGs were validated using qRT-PCR, confirming the accuracy of the RNA-Seq findings. This study delves into the functional genes and metabolic pathways closely associated with maize’s response to S. turcica infection, providing foundational data for a deeper understanding of the molecular mechanisms underlying the interaction between S. turcica and maize.