ABSTRACT Glomerella leaf spot (GLS), caused by Colletotrichum spp., persists between seasons mainly in fallen leaves on the orchard floor and in dormant plant tissues, which act as primary inoculum sources for disease initiation in spring. Because early epidemic development is strongly dependent on the availability of primary inoculum, practices such as the removal of fallen leaves could delay symptom onset and contribute to reducing disease progress. This study evaluated whether reducing primary inoculum originating from fallen apple leaves on the orchard floor affects the onset and progress of GLS. Two field experiments were conducted during the 2020/21 (Exp1) and 2021/22 (Exp2) seasons, comparing treatments with and without the removal of symptomatic leaves fallen on the ground during the dormant period. Overall, the presence or removal of fallen leaves did not influence the incidence of latent infections in leaves nor reduce the area under the disease progress curve. In Exp2, the number of conidia captured by spore traps was higher in traps positioned at 1.80 m above the ground, regardless of the presence of fallen leaves on the orchard floor. These results indicate that the management of fallen leaves alone is insufficient to substantially reduce the primary inoculum of Colletotrichum . This finding is particularly relevant in orchards with a history of GLS epidemics, where inoculum is likely already established in perennial plant tissues. Therefore, additional and integrated management strategies are required to effectively reduce disease progress driven by primary inoculum.
ABSTRACT Abelmoschus esculentus L. Moench, also known as okra, is an important nutritionally and economically valuable agricultural crop in the tropical and subtropical region. Globally, around 11,232,656 tons of okra production is carried out in 1,142,996 ha, with the productivity of 9.81 tons per hectare. However, this limited productivity occurs due to the major viral diseases infecting okra. These include begomoviruses such as Okra yellow vein mosaic virus (OYVMV), Bhendi yellow vein mosaic virus (BYVMV) and Okra enation leaf curl virus (OELCuV), which are spread by the whitefly Bemisia tabaci . In many cases, these infect in mixed combinations with the RNA virus Cucumber mosaic virus (CMV). The conventional methods like ELISA and symptom observation are found inadequate; however, approaches like PCR, quantitative PCR and next‐generation sequencing offer great sensitivity, specificity and strain typing. Recombinase polymerase amplification (RPA) and loop‐mediated isothermal amplification (LAMP), with the latest advancements in isothermal technologies, enable rapid and field‐deployable diagnostics. The main defence measures include cultural practices like intercropping, field hygiene and timely planting, with vector control by biocontrol and insecticides being vital for the control of disease. The genetic approaches of RNA interference and CRISPR/Cas‐mediated genome editing have great potential for long‐lasting resistance. This review brings together existing understanding of the biology, diversity, diagnostics and okra viral disease management, focusing on recent advances in molecular and genomic research. Through the recognition of diagnostic needs, emphasizing integrated disease management models, diagnostic assays and delving into future trends in biotechnology, it emphasizes the necessity of sustainable, multifaceted approaches to counteract viral infection and protect okra production.
ABSTRACT During November–January 2023–2024, severe anthracnose symptoms were observed on indigo ( Indigofera tinctoria ) plants in Kalyani, West Bengal, India, causing irregular necrotic lesions on leaves, pods and apical branches. A morphologically uniform fungal isolate (ITNK‐4) was consistently recovered from symptomatic tissues. On Potato Dextrose Agar, colonies exhibited whitish‐grey, woolly aerial mycelium with hyaline, smooth‐walled, cylindrical conidia and melanised appressoria. Based on these morphological characteristics and a multilocus maximum‐likelihood phylogenetic analysis of the internal transcribed spacer ( ITS ), beta‐tubulin ( TUB2 ) and glyceraldehyde‐3‐phosphate dehydrogenase ( GAPDH ) regions, the isolate was identified as Colletotrichum siamense . Pathogenicity was confirmed by artificially inoculating healthy I. tinctoria leaves with a 14‐day‐old fungal spore suspension, resulting in symptoms identical to those observed in the field, thereby fulfilling Koch's postulates. To our knowledge, this is the first molecularly confirmed report of C. siamense causing leaf anthracnose on I. tinctoria in India. Given the high economic value of I. tinctoria in natural dye production and traditional medicine, the emergence of this pathogen poses a newly characterised threat to its commercial cultivation and warrants further epidemiological monitoring.
ABSTRACT Rain tree ( Samanea saman ) is a widely planted ornamental and shade tree in Thailand. In February 2025, root galls were observed on a mature rain tree at Kasetsart University, Bangkok, Thailand, although no visible above ground symptoms were present. The causal agent was identified as Meloidogyne javanica based on perineal pattern morphology, species‐specific SCAR‐PCR, and sequence analysis of the 18S rRNA region. Pathogenicity was confirmed by inoculating 500 second‐stage juveniles (J2s) onto 45‐day‐old rain tree seedlings. Inoculated plants developed root galls, egg masses and eggs, whereas non‐inoculated controls remained symptomless. M. javanica was re‐isolated from inoculated plants, fulfilling Koch's postulates. This is the first report of M. javanica infecting rain tree in Thailand.
ABSTRACT Plant diseases remain a major constraint on global food security and ecosystem stability, yet plant disease biology has long been shaped by fragmented and reductionist frameworks. Classical concepts, such as the disease triangle, have provided valuable heuristic guidance but are increasingly insufficient to capture the dynamic, multiscale and adaptive nature of disease systems under real‐world conditions. This review critically examines plant disease biology from an integrative perspective that connects molecular mechanisms, ecological dynamics, soil processes and management strategies. At the molecular scale, advances in plant immunity, pathogen effector biology and genomic plasticity have expanded mechanistic understanding of host–pathogen interactions, although predictive capacity often declines beyond controlled environments. Ecological perspectives instead frame disease as an emergent property arising from interactions among host populations, microbial communities, environmental heterogeneity and climate variability, challenging linear and deterministic interpretations of disease causation. Soil–plant–microorganism interactions further highlight the regulatory role of biologically active soils, where microbial diversity, suppressive communities and rhizosphere processes influence disease expression. Management practices interact with these molecular and ecological mechanisms, generating evolutionary and ecological feedbacks that shape long‐term disease dynamics, rendering strategies based solely on pathogen suppression increasingly inadequate. By synthesizing recent conceptual and empirical advances, this review advocates a shift toward systems‐based and ecologically grounded approaches emphasizing regulation, resilience and adaptive management. We propose a framework in which plant diseases are understood as emergent phenomena of complex adaptive systems, improving predictive capacity and supporting sustainable disease management under environmental change and agricultural intensification.
ABSTRACT Huanglongbing is present in tropical and subtropical regions and poses a significant challenge to global citrus production, as there is currently no cure for the disease. Timely detection is crucial for effectively managing affected trees and preventing disease propagation, thereby minimizing further losses for producers. This review presents an overview of the disease, illustrating the symptoms observed in affected trees and the economic impact of the disease in different regions of the world. One of the primary challenges is the ease with which it can be mistaken for other diseases by those lacking experience. To address this, techniques employing diverse machine learning algorithms have been utilized to discern and identify characteristics and patterns in orange trees' leaves, as this is one of the most conspicuous manifestations of the disease. This work summarizes several research works on HLB detection using Deep Learning algorithms and spectroscopy techniques in HLB images of leaves and describes the most used datasets. This represents a promising avenue for advancing the field. These techniques are integral to implementing smart agriculture, facilitating broader access to new technologies that could help prevent the spread of disease and reduce production losses. This review identifies a significant gap between laboratory‐scale accuracy and field‐level reliability, highlighting the urgent need for cross‐dataset validation and standardized environmental noise suppression.
ABSTRACT Wheat diseases caused by rapidly evolving fungal pathogens remain a major constraint on global crop production and food security. Nucleotide‐binding leucine‐rich repeat (NLR) proteins are a major class of intracellular immune receptors that mediate effector‐triggered immunity and play central roles in resistance to rusts, powdery mildew, and other fungal diseases. Recent advances in wheat genomics, pan‐genomics, and targeted cloning technologies have greatly accelerated the identification and characterization of NLR genes, revealing extensive diversity in their sequence composition, domain architecture, genomic organization, and evolutionary dynamics. In this review, we synthesize current knowledge of the wheat NLRome, with emphasis on structural variation, functional diversity, and the expanding catalogue of experimentally validated resistance genes. We discuss the molecular basis of NLR‐mediated recognition and activation, including direct and indirect effector detection, paired NLR systems, tandem kinase‐NLR modules, and resistosome formation. We also highlight the major genomics‐assisted approaches that have transformed wheat resistance‐gene discovery, including RenSeq, MutRenSeq, AgRenSeq, long‐read sequencing, and emerging high‐throughput functional validation platforms. By integrating genomic diversity, molecular mechanism, and translational breeding perspectives, this review provides a comprehensive and updated framework for understanding NLR‐mediated immunity in wheat. This synthesis not only clarifies current progress in wheat immune receptor biology, but also outlines future directions for resistance‐gene discovery, functional validation, and the development of durable disease‐resistant wheat cultivars.
ABSTRACT Root‐lesion nematodes ( Pratylenchus spp.) pose a significant threat to agriculture globally. Pratylenchus spp. are widely distributed across sub‐Saharan Africa (SSA) and they affect a wide range of subsistence and cash crops. Their damage and economic importance are often underestimated. These nematodes interact with other soil pathogens leading to disease complexes and increased crop damage. Recent studies in SSA have expanded the list of known hosts for P. goodeyi and identified new species such as P. mahindii and P. vandenbergae which pose a threat to crop production. The damage caused by Pratylenchus spp. mimics nutrient or water stress which makes it a hidden threat especially for small holder farmers. Limited awareness on the existence of these nematodes constrains management options, leaving small holder farmers vulnerable to significant losses on important crops. This paper reviews the current knowledge on biology and life cycle of Pratylenchus spp., their synergistic interactions with other soil pathogens, newly identified species in SSA, and influence of environmental variables on Pratylenchus spp. It also discusses their economic importance and management options available for small holder farmers in order to safeguard food security in SSA.
Ageratina altissima is an ecosystem-disturbing invasive plant widely distributed in modified habitats across South Korea. In October 2025, leaf spot disease was observed on A. altissima in Bucheon and Guri, South Korea. The causal agent was identified as Corynespora cassiicola based on morphological characterization and a phylogenetic analysis of the ITS and LSU regions of the rDNA. The artificial inoculation of healthy A. altissima leaves resulted in symptom development, and the same fungus was reisolated, fulfilling Koch's postulates. This is the first global report of leaf spot caused by C. cassiicola on A. altissima.
Fusarium oxysporum possesse a significant threat to many vegetables, including pea (Pisum sativum) and tomato (Solanum lycopersicum), causing vascular wilt. Two F. oxysporum isolates, FP and FT, were isolated from wilted pea and tomato plants in fields with a 90% disease incidence. The identity of the isolates was confirmed through conidia morphology, multi-locus phylogeny (ITS, LSU, Ef1 alpha) and pathogenicity assays. Both exhibited strong pectinolytic activity, with the F. oxysporum FT isolate showing a higher degradation index. Full-length sequences of endo-polygalacturonase (pg1) and exo-polygalacturonase (pgx1) genes were cloned, sequenced and analysed to assess structural variation and phylogenetic relationships. The pg1 displayed greater sequence variation than the pgx1. Both genes exhibited high sequence similarity with known pathogenic F. oxysporum strains and distinct polymorphisms among other Fusarium species. Homology modelling and molecular dynamics simulations confirmed the structural and functional stability of PG1 and PGX1 proteins, with a predicted active site for substrate binding supporting roles in infection. This study provides structural and phylogenetic insights into the F. oxysporum polygalacturonases and the efficiency of the enzymes for the degradation of pectic substances of the host tissue for penetration and establishment of infection into the host.
ABSTRACT Despite a 25% increase in Indonesia's grape yield over the past 5 years, the industry faces a critical threat from grapevine leaf rust (GLR) caused by N. meliosmae‐myrianthae . GLR can induce yield losses exceeding 70% in tropical environments. This study evaluated host resistance across various Vitis vinifera cultivars by quantifying the latent period, pustule formation, and overall disease incidence. The results revealed distinct resistance profiles among the tested genotypes. The ‘Isabella’ cultivar exhibited high susceptibility, driving rapid disease onset with a short latent period. In contrast, ‘Ilaria’ and ‘Angelica’ demonstrated partial resistance, evidenced by a delayed latent period of 8 days. Most significantly, ‘Sansekerta’ and ‘GoZV’ consistently displayed superior resistance, recording the lowest pustule density, disease incidence, and area under the disease progress curve. These findings suggest that while susceptible varieties facilitate rapid polycyclic epidemics, the adoption of resistant cultivars such as ‘Sansekerta’ and ‘GoZV’ is a vital strategy for sustainable GLR management in tropical viticulture.
ABSTRACT Spinacia oleracea L. is a major vegetable crop in China, accounting for 70% of the global planting area. In October 2024, leaf mould disease with a 65% incidence was observed on spinach in greenhouses in Niutou Town, Weifang, Shandong Province. The lower leaves turn yellow first then developed into white spots; they were circular to nearly circular, ranging from 0.3 to 20 mm in size. Through experiments, fourteen fungal strains were isolated. Their colony and conidium morphology matched the genus Curvularia . Multilocus sequence analysis (tef1α, ITS, LSU) showed 99.26%–99.82% identity to Curvularia hominis , and phylogenetic trees clustered the isolates with C. hominis . Pathogenicity tests confirmed that the representative strain Bocai7 induced typical symptoms, and the pathogen was reisolated successfully, fulfilling Koch's postulates. This is the first report of C. hominis causing spinach leaf mould, which threatens spinach yield and quality by impairing photosynthesis and nutrient transport.
Plants of Euonymus japonicus (Celastraceae), an ornamental shrub, exhibiting powdery mildew symptoms were collected in Pelotas, state of Rio Grande do Sul, Brazil. Based on morphological characteristics, including conidia, conidiophore, and appressoria, as well as analysis of the internal transcribed spacer (ITS1-5.8 s-ITS2) region, the causal agent was identified as Erysiphe euonymicola. Pathogenicity was confirmed by inoculating five healthy branches of E. japonicus with conidia collected from symptomatic leaves. Typical powdery mildew symptoms developed 10-12 days after inoculation only on fungal inoculated branches, whereas control plants remained asymptomatic. To the best of our knowledge, this is the first record of E. euonymicola infecting E. japonicus in Brazil.
In July 2024, a leaf blight disease was observed on Platanus & times; acerifolia in Shandong Province, China. Symptoms appeared as necrotic lesions at leaf margins, gradually expanding inward and causing leaf scorch. Morphological characteristics placed the isolated fungus within the Colletotrichum gloeosporioides species complex. Molecular identification based on ITS, ACT, CHS-1, TUB2 and GAPDH sequences showed 99.25%-100% similarity with C. gloeosporioides reference strains. Koch's postulates were fulfilled through pathogenicity tests using three inoculation methods on adult trees, potted seedlings and detached leaves. Based on our investigation, this is the first report of C. gloeosporioides causing leaf blight on P. & times; acerifolia in China.
Fungal diseases significantly reduce the postharvest quality and marketability of durian ( Durio zibethinus ), especially in regions with humid tropical climates such as the Mekong Delta, Viet Nam. This study aimed to isolate and identify pathogenic fungi associated with diseased durian fruits and leaves, and to evaluate the antifungal potential of leaf extracts from five Rubiaceae species ( Ixora duffii , Neonauclea orientalis , Neolamarckia cadamba , Paederia lanuginosa , and Paederia scandens ). Nine fungal isolates were first obtained, among which three representative isolates were identified through morphological and molecular analyses as Lasiodiplodia theobromae , Diaporthe lithocarpus , and Lasiodiplodia pseudotheobromae . Pathogenicity tests confirmed their ability to induce fruit rot or leaf lesions. Antifungal assays revealed that all Rubiaceae extracts inhibited mycelial growth in a concentration‐dependent manner. Notably, Ixora duffii and Neonauclea orientalis demonstrated the highest activity, achieving complete suppression of Lasiodiplodia theobromae at 6.4 mg/mL, comparable to commercial fungicide control. These results indicate that Rubiaceae species, especially Ixora duffii , may serve as useful sources of antifungal compounds for improving the sustainable management of postharvest diseases in durian.
Tylenchulus semipenetrans (Cobb 1913) is an important plant‐parasitic nematode that severely affects citrus nurseries and orchard productivity worldwide. It infects feeder roots of young citrus plants, leading to ‘slow decline’ symptoms such as stunted growth, leaf yellowing and weakened root systems. These early symptoms highlight the need for timely detection and intervention. Nursery plants serve as primary inoculum sources for field infestations, emphasising the importance of quarantine and effective sanitation. This review explores the nematode's biology, morphology, host interactions, advanced techniques for early detection and the unique challenges it poses in nursery environments. Emphasis is placed on recent advancements in detection methods and integrated management strategies. These include the use of bio‐intensive approaches, deployment of resistant rootstocks, and manipulation of the rhizosphere microbiome to suppress nematode populations. The paper also highlights the importance of sustainable, holistic solutions that combine traditional and innovative practices. By integrating the most recent scientific findings and management approaches, this review aims to support the development of nematode‐free nursery systems, ultimately promoting resilient and sustainable citrus production across affected regions.
The phytosanitary quality of apple rootstocks is a key determinant of sustainable orchard production, as latent viral and viroid infections are readily transmitted through vegetative propagation. In Kazakhstan, systematic molecular monitoring of apple rootstock material remains limited. The aim of this study was to assess the prevalence of major viral and viroid pathogens in apple rootstocks used in nursery systems in Kazakhstan using RT-qPCR. Molecular testing covered nine regulated viruses and viroids of the genus Malus. Positive results were obtained for four pathogens: Apple chlorotic leaf spot virus (ACLSV), Apple stem pitting virus (ASPV), Apple green crinkle-associated virus (AGCaV) and Apple hammerhead viroid (AHVd). AGCaV was the most widespread, being detected in the majority of the samples, whereas AHVd was observed only sporadically, with a borderline amplification signal indicating a very low viroid titre, and is reported here for the first time in Kazakhstan. The detection of ASPV and ACLSV confirms the presence of mixed latent infections in apple rootstock material. These findings highlight the presence of hidden viral infections in nursery material and underscore the urgent need for a national certification system, regular molecular monitoring and the development of in vitro sanitation programmes. Such measures are essential to ensure the phytosanitary safety and competitiveness of Kazakhstan's fruit production sector.
Carrot is a widely cultivated root vegetable valued for its nutritional and health benefits. Carrot roots showing blue mould symptoms were collected from three locations in Serbia, and 11 fungal isolates were obtained. Representative isolates were identified using a polyphasic approach based on cultural characteristics on three media, at three incubation temperatures, multilocus sequence analysis of the internal transcribed spacer (ITS), beta-tubulin (BenA), calmodulin (CaM) and RNA polymerase II second largest subunit (RPB2), as well as phylogenetic analysis and pathogenicity test. BLASTn analysis showed 99.80-100% similarity with previously deposited sequences of Penicillium expansum for all analysed loci. Lesions developed on all inoculated roots within 7 days in pathogenicity assay. The combined results identified P. expansum as the causal agent of postharvest carrot root rot. Although this species has previously been associated with carrot spoilage, this study provides the first experimental verification of Koch's postulates worldwide, conclusively confirming P. expansum as a postharvest pathogen of carrot. Given its strong mycotoxigenic potential and broad host range, the occurrence of P. expansum on stored carrots represents a significant threat to both crop quality and food safety, highlighting the importance of routine postharvest monitoring and reliable, polyphasic diagnostic approaches.
We conducted a 3-year field study to determine whether downy mildew-infested onion residues incorporated into soil serve as primary inoculum under field conditions. We also clarified the timing of appearance and symptom characteristics of plants exhibiting primary infection. Pathogen-free onion seedlings were transplanted into the main field in late November. Plants exhibiting chlorosis and down-curled leaves, diagnostic of primary infection, occurred only in plots with incorporated infested residues. None appeared in untreated controls, demonstrating soilborne primary infection derived from incorporated residues. Cumulative incidence in residue plots reached approximately 2%-6% across years, with symptomatic plants appearing intermittently from mid-late February to mid-late March. In the 2 years with leaf-emergence records, symptoms first appeared mainly during 6th-7th leaf emergence after transplanting three-leaf-stage seedlings. Sporangia were usually first detected on the 4th-5th leaves. Across successive symptomatic leaves, sporangia were detected in the basal-middle regions of the lowest leaf and tip-middle regions of the uppermost leaf, revealing a positional pattern. We demonstrated that these sites corresponded to leaf-curl regions. These results constitute the first field-based evidence, supported by appropriate controls, that infested residues can trigger soilborne primary infection by Peronospora destructor. This reinforces the value of measures such as crop rotation and summer flooding. The timing and growth stage of plants showing primary infection symptoms can inform the initiation of prophylactic fungicide applications against secondary spread. The characteristic symptom patterns documented for primarily infected plants can serve as field indicators for their early detection and removal.
Branch dieback symptoms are becoming increasingly common in fig (Ficus carica L.) orchards throughout southern Iran, the country's primary fig-producing region. During surveys of commercial orchards, fungal isolates from Alternaria spp. and Bipolaris spp. were obtained from symptomatic branches of the economically significant 'Sabz' cultivar. Through morphological characterization and phylogenetic analyses based on the translation elongation factor 1-alpha (tef1), glyceraldehyde-3-phosphate dehydrogenase (gapdh), and major allergen alt a 1 (Alta1) genes, for Alternaria alternata isolates, and the tef1 gene for B. sorokiniana isolates, these fungi were identified to species level. Pathogenicity tests on detached shoots demonstrated that all isolates caused brown lesions and wood discoloration, with notable differences in aggressiveness. Principal component analysis (PCA) of aggressiveness data divided the A. alternata isolates into four distinct groups. Isolates from symptomatic trees in Ij, Fars Province, were significantly more aggressive than those from other areas. Pathogenicity assays revealed that both fungal species produced necrotic lesions on fig buds, leaves, and 1-year-old saplings. A. alternata consistently resulted in more severe symptoms than B. sorokiniana. Additionally, in greenhouse trials on saplings, both conidial suspensions and mycelial plugs confirmed pathogenicity, with the mycelial plug method generally leading to more extensive lesion development. Furthermore, fig cultivars showed varying susceptibility, as PCA and heatmap clustering based on six pathogenicity traits grouped the cultivars into three categories, identifying 'Gilasi' as the most susceptible and 'Matti' as the most resistant. Under the conditions tested, the findings of this study support the involvement of A. alternata and B. sorokiniana as pathogens contributing to branch dieback and discoloration of wood and inner bark tissues in fig trees from southern Iran. These findings establish A. alternata and B. sorokiniana as emerging threats to fig production in Iran and underscore the importance of incorporating resistant cultivars, such as 'Matti', into future disease management strategies.
