Fumigation of soil using chloropicrin has been proven to significantly affect soil nutrient cycling, but the mechanism by which soil potassium conversion and plant uptake is promoted remains unclear. In this study, we conducted a fumigation experiment to investigate the effects of chloropicrin soil fumigation on the conversion of soil potassium post-fumigation (days 7–70), and its mechanisms, tomatos were planted in fumigated and non-fumigated soils to enable further comparisons. Results showed that the content of rapidly available potassium and available potassium decreased by 16–24% and 17–23% at day 28 respectively, when tomato was planted in chloropicrin-fumigated soils compared to the non-fumigated soils. The potassium content of tomato planted in fumigated soil was significantly higher than that planted in non-fumigated soil (30.3 vs. 21.9 mg g⁻¹ dry weight). Chloropicrin fumigation resulted in a significant change in the soil bacterial and fungal community structures, and trigged a long-term (at least 70-day) decrease in microbial diversity. Network analysis showed that chloropicrin soil fumigation changed microbial co-occurrence patterns by decreasing bacterial total links, nodes, and average degree, and increasing fungal total links, nodes, and average degree. Chloropicrin fumigation caused significant changes in the relative abundance of Bacillus species, which are involved in potassium dissolution. Structural equation model (SEM) suggested that fumigation with chloropicrin enhanced the contribution of soil potassium to tomato growth and reduced the contribution of bacterial communities. Together, the results of our study help in understanding the crop yield enhancement mechanism of soil fumigation.

Chinese yam (Dioscorea polystachya Turczaninow cv. Tiegun), which belongs to the family Dioscoreaceae, is widely cultivated throughout China due to its high economic and medicinal value. In June 2023, black leaf spots on Chinese yam (cv. Purple 1) were observed in Nanchang city (28.45° N, 115.49° E) of Jiangxi province, southeastern China. The incidence of the disease ranged between 70 and 85% of plants, and up to 30% of the leaves per plant were affected in the field over a 2-week period of study. Infected foliage displayed brown necrotic lesions, elliptical or irregular, with yellow halo at the edge of the lesion (0.5 to 3 cm diam.). To identify the causal agent, 32 symptomatic leaves of eight symptomatic plants were collected. Small pieces from the margin of necrotic leaf tissue (about 3 x 3 mm) were surface sterilized in 75% ethanol for 30 s followed in 0.1% HgCl2 for 1 min, and washed three times with ddH2O. Then, the pieces were transferred onto potato dextrose agar (PDA) plates and incubated at 26°C for 3 days with a 12-h light-dark cycle. From the 32 isolates, 21 exhibited similar morphology after hyphal tipping resulting in an isolation frequency of 65.6%. Colonies on PDA were initially white aerial hyphae but became grayish with age, and a reddish orange pigment on the underside. After 16 days of incubation, pycnidia were observed, which were dark, spherical or flat spherical, and 64.1 to 172.5 µm (n = 25) in diameter. Conidia were ellipsoidal, aseptate, hyaline, and 4.1 to 5.6 × 1.8 to 2.7 µm (n = 80). In addition, a blackish green discoloration was produced on malt extract agar (MEA) using the NaOH spot test. The isolates were tentatively identified as Epicoccum spp. based on morphological characteristics (Chen et al. 2017). Isolate AYZ-1 was randomly selected for identification and pathogenicity testing. Genomic DNA of the isolate (AYZ-1) was extracted and amplified by polymerase chain reaction (PCR) using ITS1/ITS4 for the internal transcribed spacer (ITS) region (White et al. 1990), Btub2Fd/Btub4Rd for the β-tubulin (TUB) region (Woudenberg et al. 2009), LROR/LR7 for the large ribosomal RNA gene (LSU) region (Rehner and Samuels 1994), and RPB2-5F2/fRPB2-7cR for RNA polymerase II second largest subunit (RPB2) region (Liu et al. 1999), respectively. The concatenated sequences (GenBank Accession No. OR574165, OR567827, OR574166, OR567828, respectively) shared 99.8 to 100% identity with Epicoccum latusicollum (OP788080, MN329871, OR428532, and OL422485, respectively). A neighbor-joining phylogenetic tree was generated based on the concatenated sequences in MEGA7, placed isolate (AYZ-1) within E. latusicollum. To fulfill Koch's postulates, healthy leaflets from three one-year-old Chinese yam (cv. Purple 1) were used as inoculation materials, using isolate AYZ-1. Two sites of each leaf were wounded with a sterile needle and covered with a piece of cotton drenched with 200 µL spore suspension (106 conidia/mL) on the left sides, while sterilized water served as the control on the right sides of leaves. All inoculated leaves were covered with clear polyethylene bags for 24 h. Plants were grown outdoors at a daily average temperature of 26°C with relative humidity over 45%. After 7 days of incubation, the leaves showed the same symptoms as the original diseased leaves. The E. latusicollum isolate was re-isolated from diseased leaves and confirmed by morphology and sequencing analysis, fulfilling Koch's postulates. E. latusicollum has been previously reported to cause black root on yam in China's south-western province of Sichuan (Han et al. 2019). Meanwhile, leaf spot have been reported on many plants by this genus, such as tobacco (Guo et al. 2020) and banana (Liu et al. 2023). According to our knowledge, this is the first report of E. latusicollum causing black leaf spot on Chinese yam in China. This finding will provide an important reference for understanding the biology of E. latusicollum and the distribution of the disease, but more research is needed to determine if management is warranted.

Root-knot nematode disease seriously threatens the production of Rui yams, making it important to explore effective management strategies, including the optimal time for disease control and efficient application techniques. In this study, we monitored the dynamics of a root-knot nematode J2 population in the soil using field sampling; moreover, we investigated the dynamics of root-knot nematode disease using a field sampling and visual in situ device based on identifying species of root-knot nematodes in Rui yams. Additionally, experiments pertaining to optimal application time and techniques were conducted in Ruichang and Nanchang. This is the first study to propose that chemical control should be optimally timed, with one application administered at the time of yam seedling flush, and another given approximately 60 days later. Applications of a 41.7% fluopyram suspension (1426 g.a.i./hm²) and a 30% fosthiazate microencapsulated suspension (2925 g.a.i./hm²) achieved disease control effects of 81.56–83.15% and 75.95–78.42%, respectively. Additionally, the comparative analysis demonstrated that using uniform root layer application technology at the optimal time produces a control effect exceeding 80%, which is significantly higher than conventional techniques such as drip irrigation and root irrigation. These results provide theoretical and technical support for the efficient control of root-knot nematode disease in Rui yams.

Sesame bacterial wilt, caused by the pathogen Ralstonia solanacearum, is a major constraint for continuous cropping. Deciphering the defense mechanisms of sesame is therefore essential to the development of novel and effective control strategies. The Non-expressor of Pathogenesis-Related 1 (NPR1) plays a key role in regulating salicylic acid (SA)-mediated systemic acquired resistance (SAR). In this study, we reported that leaf treatments with 50 μg/mL benzothiadiazole (BTH) resulted in increased protection of sesame against Ralstonia solanacearum. We clarified the structure, expression patterns, and function of a NPR1 homologous gene, SiNPR1, in sesame. The SiNPR1 gene open reading frame comprises 1758 bp, and it encodes 585 amino acids. Phylogenetic analysis revealed that SiNPR1 is closely related to NPR1-like in Olea europaea and clustered with other members of the families Monocotyledon and Dicotyledon. Quantitative real-time PCR (qRT-PCR) results demonstrated that the expression of the SiNPR1 gene was organ-specific and could be induced by BTH. The yeast two-hybrid assay confirmed that SiNPR1 directly interacts with SiTGA2. In conclusion, these results suggest that SiNPR1 plays a pivotal role in the BTH-dependent systemic acquired resistance in sesame.

Bacterial canker of the kiwifruit caused by the etiological agent Pseudomonas syringae pv. actinidiae (Psa) is the most severe disease in kiwifruit production. Since 2008, a hypervirulent Psa biovar 3 has spread rapidly worldwide. This study presents the first systematic characterization of Psa in Jiangxi Province, a major kiwifruit-growing region of China. Among 42 bacterial isolates collected from six production areas, all were identified as the highly pathogenic Psa biovar 3 through morphological, PCR-based, and multilocus sequence analyses. In vitro bioassays revealed that tetramycin exhibited the strongest inhibitory activity against a representative strain (F7), with an EC ₅₀ of approximately 0.002 mg/L, followed by bronopol, ethylicin, and benziothiazolinone. Notably, no copper-sensitive strains were detected, and all isolates showed a high level of copper resistance, with minimum inhibitory concentrations (MICs) values of 1.80–2.60 mM of copper sulfate, far above the conventional resistance threshold. These results demonstrate that Psa biovar 3 is the dominant pathogen in Jiangxi and that local populations pose a significant risk of copper resistance, highlighting the urgent need for integrated management strategies that reduce reliance on copper-based bactericides.