Pear decline, caused by 'Candidatus Phytoplasma pyri', has emerged in Chilean pear orchards in recent years. While several Cacopsylla species are potential vectors of 'Ca. P. pyri', the disease's full epidemiological cycle remains uncertain. Cacopsylla bidens, present in Chilean orchards, has recently been reported as a vector. This study conducted year-long surveys in two commercial pear orchards across different Chilean regions, capturing C. bidens in zones with 'Ca. P. pyri'-infected pear trees. All developmental stages were collected, with peak abundances occurring in March and April. Outside the study zones, C. bidens were found in pine trees but not in adjacent cultivated areas. Two seasonal morphotypes, summer and winter forms, were identified. Molecular analysis detected 'Ca. P. pyri' in a high proportion of insects, with maximum infection rates in March and April. These findings advance our understanding of 'Ca. P. pyri' spatial and temporal dynamics and its potential role in 'Ca. P. pyri' spreading under Chilean field conditions.

Xanthomonas arboricola pv. pruni (XAP) causes bacterial spot of peach. Current disease management in the southeastern USA mainly relies on routine applications of copper and oxytetracycline (OTC), but copper-tolerant and OTC-resistant XAP have been reported in South Carolina (SC) peach orchards. To study the prevalence and persistence of copper-tolerant and OTC-resistant XAP, a survey was conducted across seven SC and Georgia peach orchards/farms annually during 2021 to 2024. Of the 1,741 XAP isolates collected, 4.4% were copper sensitive; 24.3%, 65.5%, and 5.8% were copper-tolerant up to 150 (LCT150), 175 (LCT175), and 200 µg/ml of copper sulfate pentahydrate, respectively. All the OTC-resistant isolates (24.9% of the population) came from the three conventional SC orchards and contained tetC. In the same orchards, trees with OTC-resistant isolates had significantly higher bacterial spot incidence and severity on both fruit and leaves than the other trees, while higher bacterial leaf spot incidence was observed on trees with LCT175 vs. LCT150 XAP, suggesting potential negative impact of OTC resistance and copper tolerance on the chemical spray programs. In each orchard, bacterial spot incidence, severity, and defoliation increased over time within each season, but the percentage of the resistant/tolerant XAP population remained similar. Regardless of the spray programs utilized, copper-tolerant and OTC-resistant XAP populations have been consistently recovered from the sampled trees across years. Season-long chemical spray programs are still valuable for this disease, but the prevalence and persistence of copper-tolerant and OTC-resistant XAP emphasizes the need for resistance management and development of novel disease management strategies.

Mungbean (Vigna radiata) and cowpea (Vigna unguiculata) are economically important legumes widely cultivated in China. Phytoplasmas are phloem-limited plant-pathogenic bacteria transmitted by the phloem-sucking insect vectors (e. g., leafhoppers, planthoppers, and psyllids) (Kumari et al. 2019; Wang et al. 2024). In October 2025, typical phytoplasma-like symptoms of phyllody, witches’ broom, small leaves, wrinkling were observed on mungbean and cowpea plants at the harvesting stage in Wuming district, Nanning city, Guangxi, China, with a disease incidence of less than 10%, which may represent a potential, yet unconfirmed, risk to local mungbean and cowpea cultivation. To determine the causal agent, total DNA was extracted from symptomatic and healthy leaf midribs (2 symptomatic, 1 healthy sample per crop from the same field plot) using the CTAB method. The 16S rRNA and tuf genes were amplified via nested PCR with primer pairs P1/P7 and R16F2n/R16R2 (Gundersen and Lee 1996) or fTuf1/rTuf1 (Schneider and Gibb 1997), respectively. Approximately 1800 bp and 1250 bp (for 16S rRNA) or 1000 bp (for tuf) fragments were amplified from symptomatic mungbean and cowpea samples, but no amplicons from healthy controls. The PCR products were purified, cloned into a TA vector, and transformed into Escherichia coli cells for sequencing. The 16S rRNA gene sequences from mungbean and cowpea were both 1806 bp in length and identical to each other. Representative sequences were deposited in NCBI GenBank under accession numbers PX597226 (Mungbean phyllody phytoplasma GX-NN-01) and PX597227 (Cowpea phyllody phytoplasma clone GX-NN-01). BLASTN analysis of 16S rRNA sequences revealed a 99.94% identity (1,805/1,806 nt) with Candidatus Phytoplasma australasiaticum strain CrWB-Hnsy1 (16SrII-A subgroup, GenBank accession no. EU650181), a provisional species in the 16SrII group, from Crotalaria pallida in Hainan, China. Further, virtual RFLP analysis of the P1/P7-amplified 16S rRNA gene sequences were performed using the online iPhyClassifier tool (Zhao et al. 2009), further confirming the classification of the isolated phytoplasmas into the 16SrII-A subgroup (Peanut WB group). Additionally, a neighbor-joining phylogenetic tree constructed using MEGA 11 (Bootstrap value 1,000) confirmed that the phytoplasmas from mungbean and cowpea clustered within the 16SrII group. To our knowledge, this is the first report of 16SrII group-related phytoplasmas infecting mungbean and cowpea in Guangxi, China. This finding highlights a new threat to local legume cultivation and provides a foundation for further studies on the dissemination of phytoplasma diseases in legumes.

In 2019, kiwifruits (Actinidia chinensis cv. ‘Huayou’) with typical soft rot symptoms (54% incidence, n=200) were randomly collected from a commercial orchard in Shaanxi Province, China (107°39′E, 33°42′N). Lesions were round or oval, with yellowish centers and a water-soaked margin between infected and healthy tissue (Fig. 1a). Tissue segments (4×4 mm) taken from lesion margins of five decayed fruits were surface-disinfected (1% NaClO, 30 s; 70% ethanol, 60 s), rinsed with sterile water, air-dried on filter paper, and plated on PDA at 25 °C for 3 days. Hyphal tips were transferred to PDA for pure cultures. A total of 13 fungal isolates were obtained, including two previously unidentified strains (SXHY2-1 and SXHY3-1) and 11 reported strains (two Botryosphaeria dothidea and nine Diaporthe spp.). In 2021, two additional phenotypically similar strains (SXHY2-2 and SXHY3-2) were isolated from the same orchard. On PDA, SXHY2-1 and SXHY2-2 exhibited purple-red central hyphae with white margins, while SXHY3-1 and SXHY3-2 produced abundant white aerial mycelium (Fig. 1b, c). All four isolates produced similar conidia on carnation leaf agar (CLA). Macroconidia were slender, thin-walled, 3-4 septa, measuring 25.1-54.9×3.1-6.2 µm (mean 44.9 × 4.5 µm, n=35). Microconidia were oval, elliptical, or kidney-shaped, 0-1 septum, 4.8-14.4×1.4-4.0 µm (mean 8.6 × 2.8 µm, n=35) (Fig. 1d, e). Chlamydospores were terminal or intercalary, rough-walled, single or paired, 5.6-12.8 µm in diameter (mean 8.1 µm, n=35) (Fig. 1f, g). Conidiogenous cells were short monophialides with 2-5 loci (Fig. 1h, i). These features matched Fusarium odoratissimum (Maryani et al., 2019; Ujat et al., 2021). The four isolates were identified by sequencing RPB1, RPB2, and EF1-α genes using specific primers (O'Donnell et al., 2010). With SXHY3-2 identical to SXHY3-1, the sequences of RPB1 (MW646527, PX596509, MN264748), RPB2 (MW646526, PX596510, MN264750), and EF1-α (MW646525, PX548364, MN264749) were obtained from SXHY2-1, SXHY2-2, and SXHY3-1, respectively. Polyphasic identification with the three sequences by Fusarium MLST, SXHY2-1, SXHY2-2 and SXHY3-1 shared 99.83%, 98.18%, 99.70% identity respectively with the F. odoratissimum strain LC13762. BLASTn analysis confirmed that isolates SXHY2-1, SXHY2-2 and SXHY3-1 shared 99.22 to 100% identity in their EF1-α, RPB1, and RPB2 genes with F. odoratissimum reference sequences (OR865337, PV613661, OR865341). Phylogenetic analysis (Maximum Likelihood, MEGA7) of the combined dataset confirmed all four strains as F. odoratissimum (Fig. 2). For pathogenicity tests, surface-disinfested fruits of ‘Xuxiang’ (A. deliciosa) and ‘Sungold’ (A. chinensis) were rinsed and air-dried. Wounds (3 mm deep) were inoculated with 15 µL of conidial suspension (1×10⁶ cfu/mL); controls received sterile water. Fruits were incubated at 25 °C and 80% RH. Watery soft decay developed on all inoculated fruits within seven days. The mean lesion diameter was 24.5±1.2 mm on 'Xuxiang'(n=15) and 17.5±0.9 mm on 'Sungold' ( n=15 )(Fig.1j-1m). Control fruits remained healthy. The test was conducted twice. Fungi re-isolated from lesions were confirmed as F. odoratissimum based on morphology and RPB2 sequencing. F. odoratissimum (formerly F. oxysporum f.sp. cubense) is a distinct species due to genomic differences (Maryani et al., 2019; Ujat et al., 2021; van Westerhoven et al., 2023). As far as we know, this is the first report of F. odoratissimum causing kiwifruit rot.

Water spinach (Ipomoea aquatica Forsk.) is a species in the Convolvulaceae family and a leafy vegetable commonly cultivated in Asia, particularly in China and India (Hao et al. 2021). In Florida, USA, it is grown as a specialty crop in moist soil or hydroponic systems. In November 2024, water spinach plants with dark leaf spots from a registered farm were observed and maintained in a greenhouse for study. In February 2025, irregular brown leaf spots with a yellow halo were observed (≈60% incidence, 15% severity). Small leaf sections (0.5 cm) were excised, surface-sterilized in 75% ethanol for 30 s and 1% NaClO for 1 min, then rinsed twice with sterile water, air dried, plated on 1% water agar, and incubated at 25°C in the dark. After six days, mycelia emerging from tissue were subcultured on PDA and incubated for seven days. Colonies were velvety to woolly, olivaceous gray to brown. Conidiophores were mostly straight, unbranched, brown, septate, and apically geniculate, with terminal conidiogenous cells. Conidia were typically curved, ellipsoidal, 15.3–28.4 (22.8 ± 3.3) × 7.2–12.6 (10.2 ± 1.3) µm (n = 40), with 3–4 septa, a hyaline apical cell, and an enlarged dark brown to black, sometimes thick-walled central cell. Morphology was consistent with Curvularia asiatica (syn. C. asianensis) (Manamgoda et al. 2012). Genomic DNA was extracted from WY6 using the Quick-DNA Fungal/Bacterial Miniprep Kit (Zymo Research). ITS, GAPDH, and TEF1 were amplified and sequenced with primers ITS1/ITS4 (White et al. 1990), gpd1/gpd2 (Berbee et al. 1999), and EF1-983/EF1-2218R (Schoch et al. 2009). Sequences were deposited in GenBank as PX555836 (ITS), PX693380 (GAPDH), and PX693379 (TEF1). ITS showed 100% identity to C. millisiae (OK661031), whereas GAPDH and TEF1 matched C. asiatica (100% MN264083; 99.8% MK886804). Because ITS has limited resolution in Curvularia, multilocus phylogeny (ITS+TEF1+GAPDH) placed WY6 within the C. asiatica clade, with C. senegalensis as the closest relative. However, C. senegalensis has intercalary conidiogenous cells and larger, 3–5 septate conidia (22–31 × 10–14 µm) (Spegazzini, 1914; Guarro et al., 1999), whereas C. asiatica has only terminal conidiogenous cells and smaller conidia with ≤4 septa, consistent with our observations. Therefore, based on morphology and phylogeny, WY6 was identified as C. asiatica. Pathogenicity tests were conducted on water spinach in a greenhouse at 28–32°C. Inoculum of C. asiatica WY6 was prepared by suspending conidia from 8-day PDA cultures in sterile water and adjusted to 1 × 10 6 conidia/mL. Five plants were sprayed with 50 mL of spore suspension, and five controls plants received sterile water. Plants were bagged for 48 h to maintain humidity. Five days after inoculation, four of the five plants developed brown lesions with a yellow halo, like the original symptoms, while controls remained healthy. The pathogenicity test was repeated twice with similar results. Koch’s postulates were fulfilled by reisolating C. asiatica from all symptomatic leaves, confirmed morphologically. To our knowledge, this is the first report of C. asiatica infecting water spinach (I. aquatica). This species has been reported as a saprobe on grasses (Panicum spp.), sugarcane and rice, and as a pathogen on Epipremnum pinnatum (Manamgoda et al. 2012) and Sansevieria trifasciata in Malaysia (Kee et al. 2020). This finding expands the host range and distribution of C. asiatica and highlights the need for management strategies in water spinach.

In 2023, one tomato plant showing symptoms typical of tomato spotted wilt virus (TSWV; Orthotospovirus tomatomaculae), including necrotic spots on older leaves, concentric rings, stunting, and progressive wilting, was submitted from Marengo Co., Alabama (AL), to the Vector Entomology Laboratory for analysis. In 2024, three additional samples with the same symptoms were received from the Chandler Mountain area of northeast AL (St. Clair Co.). Leaf tissues from symptomatic plants collected in 2023-24 were processed for Sanger sequencing of TSWV NSm as described (Shehata et al. 2025a). NSm sequences from 2023 (four colonies sequenced from a single sample; PX634739-742) lacked resistance-breaking (RB) mutations. In contrast, 2024 NSm sequences (five colonies sequenced from three samples; PX634743-747) had V49A, C118Y, and V141I substitutions. The C118Y is associated with Sw-5b RB in tomato in Spain (Lopez et al. 2011). In 2025, growers in the same production region reported a severe outbreak of TSWV. To determine whether TSWV-RB with the C118Y mutation was circulating, and to test the Sw-5b RB phenotype under greenhouse conditions, we collected 10 samples with different TSWV-resistance backgrounds from three farms (Farms I-III). Seedlings of Sw-5b resistant cultivar ‘Mountain Merit’ and TSWV susceptible cultivar ‘Beefsteak’ were grown under greenhouse conditions, and 25 seedlings from each variety were mechanically inoculated with TSWV-infected leaf tissues from Farm III (Shehata et al. 2025b) at 17d after emergence. At 13d post-inoculation, plants from both varieties showed typical symptoms of TSWV. Infection was confirmed using Enzyme-Linked Immunosorbent Assay (ELISA) (AgDia, Elkhart, IN), while healthy controls were negative. Moreover, NSm was sequenced from both 2025 field samples and mechanically inoculated plants, resulting in 20 sequences (PX634748-767): 12 from field samples (eight sequenced from individual samples across three farms and four from a pooled Farm-III inoculum) and eight from mechanically inoculated plants (four colonies per variety). Consistent with 2024, C118Y and the other two mutations were present in 2025. Another mutation (I130V) appeared in 55% of 2025 sequences (n=11/20), indicating ongoing evolution of RB strains in AL. Moreover, AL’s 2024-25 sequences shared 4/6 mutations (I163V, V290I, N293S, K296Q) with Texas RB strains lacking C118Y (Chinnaiah et al. 2023), indicating both local evolution and regionally shared lineages circulating in AL. A phylogenetic tree was constructed (Shehata et al. 2025c) to assess the relatedness of AL NSm sequences to RB and peanut-derived isolates from AL and Georgia (GA). AL’s 2023 tomato isolates, which lack the C118Y and other mutations, clustered within Sub-clade 6.3 together with peanut isolates, suggesting RB variants were likely absent from tomato in AL that year. In contrast, AL’s 2024-25 tomato isolates formed six host-associated sub-clades within Sub-clade 6.7, together with single isolates from North Carolina and GA (OP832375 and KU179600), consistent with largely local diversification of RB-associated lineages. These genomic and phylogenetic data provide the first evidence of TSWV-RB strains overcoming Sw-5b-mediated resistance in tomato in AL, making AL the third southeast state in the United States to document a severe outbreak of TSWV-RB (Macedo et al., 2024). This underscores an urgent need for more durable TSWV management and resistance strategies.

Rice viral diseases are emerging threats to tropical agroecosystems, yet their spatiotemporal dynamics and transmission ecology remain poorly understood. From 2021 to 2023, systematic field surveys were conducted across 13 rice-growing regions of Hainan Island, China, to assess virus incidence, diversity, and vector associations. Six known rice viruses were detected via RT-PCR, and virome profiling was performed using rRNA-depleted transcriptome sequencing. Brown planthopper (Nilaparvata lugens, BPH) abundance and virus-carrying rates were measured to evaluate their association with Rice ragged stunt virus (RRSV) outbreaks. Virus incidence varied markedly across ecological zones and seasons: the semi-arid to semi-humid transitional zone showed the highest infection rates (~45%), while humid and mountainous areas showed minimal detection. Incidence peaked in summer and autumn and was significantly higher in late-season rice. Virome analysis identified 18 RNA viruses, including nine novel species, spanning multiple viral families. Twelve viruses were detected in BPH and seven in rice, with RRSV being the most prevalent in both. Correlation analysis revealed a strong association between RRSV incidence and BPH virus-carrying rate (R² = 0.40, P < 0.001), but not with vector abundance. These results underscore the ecological and vector-related drivers of rice virus epidemics in tropical systems and support viruliferous vector monitoring as a tool for disease forecasting.

This study investigated the effects of near-ambient ozone (O3) and future predicted CO2 concentrations on disease severity and progress of leaf rust (LR) on wheat, caused by Puccinia triticina Eriks. (Pt). Four winter wheat cultivars (Coker 9553, NC Neuse, Jamestown, and NuEast) with differential LR resistance were assessed for their O3 responses to four O3 treatments (sub-ambient, 50, 75, and 100 ppb O3) in continuously stirred tank reactors (CSTRs) located in the greenhouse. Ozone-induced foliar symptoms on the cultivars were either absent or negligible at a near-ambient ozone concentration (50 ppb), but all cultivars showed visible injury symptoms at high O3 concentrations. The effects of long-term near-ambient O3 (50 ppb) and elevated CO2 (570 ppm) on disease severity and disease components were also assessed on flag leaves after plants were inoculated with Pt race 'MBTNB' at GS 39-40 Zadoks in outdoor-plant environment chambers (OPECs). Infection was initiated by aerosol application of urediniospores following dew formation on leaves under high humidity conditions in the OPECs. Rust resistant cultivar NuEast did not exhibit LR symptoms under gas treatments. Near-ambient O3 singly or combined with elevated CO2 (570 ppm) increased disease severity and pustule size, and accelerated pustule formation on the susceptible cultivar Coker 9553. However, elevated CO2 alone had no significant effect on disease severity. This study suggests that the interactive effect of greenhouse gases on wheat rust diseases could lead to enhanced rust epidemics.

The recent expansion of cotton acreage in the semi-arid Northern High Plains of Texas has raised concerns about the potential widespread distribution of Verticillium dahliae, the causal agent of Verticillium wilt, into these areas. These concerns were primarily driven by the use of lower seeding rates; lower summer air temperatures; the absence of completely resistant cultivars; and the region's proximity to the Southern High Plains, where the pathogen is endemic. This study was conducted to assess Verticillium wilt risk, based on microsclerotia density, in the Northern High Plains. Soil samples were collected from 26 cotton fields across 10 counties, and viable microsclerotia in 40 cm³ of soil per field were quantified using a plating assay with semi-selective media. Microsclerotia were detected in 88.4% of fields: 38.5% of fields were categorized as high risk (microsclerotia/cm³ ≥ 10), 23.1% as moderate risk (3 < microsclerotia/cm³ ≤ 9.9), 26.9% as low risk (0 < microsclerotia/cm³ ≤ 3), and 11.5% showed no detectable risk (microsclerotia = 0). All isolates/phylotypes tested belonged to the defoliating pathotype. Management recommendations tailored to the risk categories are discussed. The detection of microsclerotia in 88.4% of the fields surveyed, with 38.5% categorized as high risk, indicates a concerning level of inoculum and highlights the need for continued surveillance and further research on phenotypic and genotypic characterisation.

Rice blast is the devastating disease, caused by Magnaporthe oryzae, and presents a significant challenge to rice production impacting leaves, nodes, stems, necks, and panicles throughout the growing season. To enhance sustainable rice production and effective disease management, it is crucial to continuously monitor rice blast incidence and race diversity. An increase in the incidence of rice blast disease in Korea in 2020 and 2021 has been reported, leading to a decline in rice production, particularly in Jeonbuk, where both leaf and panicle blast were prevalent. In this study, the incidences of rice leaf blast and panicle blast were monitored nationwide from 2020 to 2022 and race diversity and pathogenic characteristics of 754 rice blast isolates collected from leaves and necks were identified. Among these, 633 isolates of race distribution were identified according to the resistant reactions of the Korean differential race system. Applying the Korean differential race system, the isolates were categorized into 40 different unique Korean races distinguishing the ability to cause disease in Japonica-type and Indica-type cultivars. Moreover, pathotypes analysis of 556 isolates using the monogenic resistance lines showed that most of the evaluated isolates reveal incompatible reactions to monogenic lines carrying resistance genes Pita-CP1, Piz-t, and Piz-5. The similarity of the pathotypes among the isolates was analyzed based on the disease reactions of the monogenic resistance lines and 28 isolates were selected as a standard representative set considering their viability, high virulence, dominant Korean races, and different reactions to resistance genes. This comprehensive study aims to inform the development of durable blast protection and provide valuable insights for breeding broad-spectrum-resistant rice cultivars.