Journal of Phytopathology最新文献

Carrot (Daucus carota L. subsp. sativus) cultivation is important in Argentina, with the Garay department in Santa Fe province being a key production area. In recent years, dry rot symptoms have afflicted various carrot cultivars, resulting in substantial field losses and postharvest discards. Several soilborne pathogens, including Fusarium species, have been implicated in similar carrot diseases globally. This study aimed to identify the specific causal agent responsible for dry rot in carrots in central Argentina to enable targeted disease management strategies. Samples of symptomatic carrots were collected from fields in the Garay department. Fungal isolates were obtained from the infected tissue and subjected to morphological and molecular analyses. Pathogenicity tests were conducted to confirm the ability of the isolates to cause disease symptoms in carrots. Based on morphological and molecular identification, isolates were identified as Fusarium nirenbergiae, Fusarium triseptatum and Fusarium solani. Pathogenicity tests demonstrated that the three Fusarium species were capable of causing dry rot symptoms in carrots. This study represents the first report of Fusarium nirenbergiae, Fusarium triseptatum and Fusarium solani causing dry rot in carrots in Argentina.

Lentil (Lens culinaris) is an important pulse crop in India. Fusarium wilt caused by Fusarium oxysporum f. sp. lentis (Fol), is a major biotic constraint in lentil production. The present investigation was undertaken to evaluate the efficacy of combination products of fungicides and bio-agents against Fol under in vitro and in vivo conditions. Fungicides were evaluated using the poisoned food technique, while the antagonistic activity of bio-agents was studied using dual culture technique. Among seven combination products of fungicides, carbendazim 12% + mancozeb 63% was the most effective fungicide in restricting the colony diameter of the pathogen. In field conditions, the seed treatment with carbendazim 12% + mancozeb 63% at 2.5 g/kg seed performed best in both yield and seed quality parameters. Among the bio-agents tested, Trichoderma asperullum gave the best results in suppressing pathogen growth under in vitro conditions. The seed treatment with the combination of T. asperullum + Pseudomonas fluorescens at 5 g/kg seed showed improvement in seed yield and seed quality parameters in the field. The present study has provided chemical and biological measures for the integrated management of lentil wilt.

It is critical to use a population of the pathogen that contains different strains to determine the resistance of grapevine varieties to the downy mildew pathogen Plasmopara viticola in a specific region. This study tested six local grape varieties (Çavuş, Kalecik Karası, Müşküle, Papaz Karası, Sultana and Yapıncak), eight Turkish registered varieties (Barış, Bozbey, Güzgülü, Özer Karası, Reçel Üzümü, Tekirdağ Çekirdeksizi, Trakya İlkeren and Yalova İncisi) and seven varieties of foreign origin (Cabernet Sauvignon, Cardinal, Chardonnay, Cinsault, Isabella, Semillon and Gamay) using detached leaf and leaf disc assays with pathogen populations collected from vineyards. There was a significant correlation for disease severity between the two assay methods. No sporulation was observed on the varieties Çavuş and Isabella in both assay methods. The variety Yapıncak had very low disease severity (2.00%) in the leaf disc assay, and the pathogen did not sporulate on this variety in the detached leaf assay. Cluster analysis was performed to determine the resistance level of the varieties against the pathogen, as different disease severities were observed in some varieties depending on the test method used, and the 21 varieties were classified into four clusters. Barış, Bozbey, Cardinal, Çavuş, Isabella, Semillon and Yapıncak in Cluster I exhibited the lowest disease severity mean (2.88%), while those in Cluster 3, including Cabernet Sauvignon, Güzgülü, Papaz Karası and Yalova Incisi, had the highest disease severity mean (56.75%). These varieties in Clusters 1 and 3 were considered highly resistant and highly susceptible, respectively. Leaf hair density, as reported in official variety descriptions, did not associate with reduced disease severity in the two assays. This study assessed the response of grapevine varieties to the P. viticola population in the region for the first time. The highly resistant and resistant varieties identified will provide new material for breeders and contribute to the improvement of organic viticulture in the area.

Rhizome rot poses a significant threat to ginger cultivation, caused by a complex interaction of pathogens such as Pythium aphanidermatum, Fusarium oxysporum, Ralstonia solanacearum, Sclerotium rolfsii and Meloidogyne incognita. The pathogens were individually inoculated at 75, 105 and 135 days after planting (DAP), as well as in various combinations, to evaluate disease severity and symptom development. Results revealed that R. solanacearum exhibited the highest disease severity and fastest symptom development across all stages of inoculation, followed by P. aphanidermatum, F. oxysporum, S. rolfsii and M. incognita. The combined inoculation of pathogens significantly increased disease incidence and rhizome rot compared to individual inoculations, indicating synergistic interactions among the pathogens. Sequential inoculation experiments demonstrated that pre-infection by M. incognita exacerbated disease severity, highlighting the role of nematodes in predisposing plants to secondary infections.

Banana cultivation has great socio-economic importance in the Cariri region (state of Ceará), Brazil. This study aimed to monitor the severity of anthracnose (caused by Colletotrichum musae) in bananas (cv. Prata) collected at three postharvest processing steps (dehanding, first washing and second washing) in packinghouses of four producing companies (A, B, C and D) in the wet (February–May) and dry (September–December) seasons of production in 2019. Averaged across packing companies and processing stages, disease severity was higher in the wet season (42.4%) than in the dry season (19.6%), but disease variability, expressed by the coefficient of variation, was higher in the dry season. In most cases, there were significant (p ≤ 0.05) differences among processing stages within each packinghouse and season, but the stage with the highest disease severity was not consistent. In other words, there was no predictable change in disease severity from dehanding to first and second washing. It was impossible to identify a single pattern in the severity of anthracnose in banana fruits collected from different companies and stages of postharvest processing, and this may be associated with the management adopted in each production area.

Chrysanthemum Fusarium wilt (CFW) is a devastating soil-borne disease affecting the cut chrysanthemum industry globally. In Vietnam, this disease has been occurring silently and is posing a risk of epidemic outbreaks in the southern provinces, especially Lam Dong. Results from a survey in 2023 showed that stunted growth, curved and small stems, dried-rot roots, leaf drooping and green or yellow wilting of plants after transplanting or at their flower bud initiation were common symptoms observed across the main chrysanthemum-growing farms in Lam Dong. The occurrence of CFW was recorded in relation with the host cultivar, irrigation method and fungicide-spraying regime. Among the cultivars grown in Lam Dong, ‘Doa cu’ was the most susceptible to CFW. The use of sprinkler irrigation and infrequent application of fungicides were attributed to increase both disease incidence and severity. Thirty fungal isolates obtained from diseased plants were identified as Fusarium oxysporum and F. falciforme based on morphological features and molecular analysis of ITS and TEF-1α genes. The detection frequency of these two species was almost equal, which shows their balanced role in the occurrence of CFW in Lam Dong. In-planta pathogenicity assays of Fusarium isolates against plantlets grown from cuttings and invitro propagation showed a variation in pathogenicity and a specialisation of isolates for these planting materials. These results suggest that the profiles of population and aggressiveness of Fusarium isolates diverged with the type of planting material, and between the stock and the commercial farms.

Synthetic fungicides are used to control anthracnose caused by Colletotrichum gloeosporioides; however, their frequent application increases the risk of pathogen resistance, environmental damage, and health concerns. It has been reported that caprylic acid (CA) inhibits the in vitro development of C. gloeosporioides; however, its antifungal mechanism and in vivo antifungal potential are still unknown. Therefore, the present work aims to analyse the effect of a CA-enriched sub-fraction (CAES) extracted from Vitex mollis fruit on the fungal microstructure by confocal fluorescence microscopy and morphometric analysis. Moreover, the effect of CAES on anthracnose development and quality parameters in papaya fruit was evaluated. The confocal microscopy images confirmed that CAES damaged the cell wall of conidia, given their decreased width. The increased fluorescence intensity in the CAES and CA-treated mycelium suggested they were attached to the plasma membrane. These treatments produced structural alterations of the vacuoles and septa in mycelium, while in the fungicide thiabendazole (TBZ) treatment, apoptotic bodies appeared. CAES at 1.0 g L⁻¹ had the best effect against anthracnose incidence and severity in papaya fruit, whereas TBZ was only effective on anthracnose severity. None of the applied treatments affected the fruit quality parameters. Therefore, CAES may be develop as an effective option to suppress anthracnose on papaya fruit.

Melon holds significant economic importance for Brazilian agribusiness. It exhibits high polymorphism and genetic variability, yet knowledge regarding its genetic diversity and response to root diseases remains limited. Therefore, this study aimed to assess the genetic diversity and response of melon plant accessions to Monosporascus cannonballus. Two trials were conducted involving 29 melon accessions and a commercial hybrid of the yellow melon plant, Natal RZ. In the first trial, the accessions and the commercial hybrid were grown in the field under a randomised complete block design with three replications. They were evaluated for fruit-related descriptors: number of fruits per plant (NFP), average fruit weight, shape index, pulp thickness, pulp firmness (PF) and total soluble solids (TSS). Standardised Euclidean distances were calculated on the basis of the results, and the accessions were grouped using the UPGMA method. In the second trial, the melon plant accessions and commercial hybrid were cultivated in a greenhouse under a completely randomised design with 12 replications. For inoculation, wheat grains infested with M. cannonballus isolate CMM-2429 were used. Evaluations were conducted 60 days after transplanting, assessing the incidence and severity of the disease, and biometric variables. The study revealed genetic variability among the evaluated accessions for fruit descriptors and response to M. cannonballus. Most divergent accessions were A16, A53, NZR, A28, A51 and A44, with divergence primarily observed in NFP, PF and TSS. Promising accessions for breeding programmes aimed at resistance to M. cannonballus included A01, A04, A25, A27 (moderately resistant) and A26 (highly resistant to the pathogen).

Neoscytalidium dimidiatum is an asexual, opportunistic and necrotrophic pathogen that causes the devastating stem canker disease of dragon fruit species (Selenicereus spp.). Despite this, information about its intraspecific diversity remains lacking. Examination of the morphological variations of 40 N. dimidiatum isolates hosted by S. megalanthus, S. monacanthus and S. undatus from eight allopatric regions in the Philippines detected three distinct morphotypes. Sequencing of three partial gene markers (ITS, ACT and TUB2) of representative isolates revealed low intraspecific genetic diversity of the pathogen from the three hosts. Phylogenetic analysis of internal transcribed spacer (ITS) sequences of the isolates in this study and worldwide collections of the phytopathogen in the GenBank database infers similar founding populations and the possible specificity of the dragon fruit-infecting N. dimidiatum. Pathogenicity and aggressiveness assay of the isolates on detached stems of dragon fruit did not detect host specificity to S. monacanthus and S. undatus. However, some isolates (i.g., MBDF0802A, MBDF0808B, MBDF0339A and MBDF0007A) significantly had shorter latent period to the stems of S. undatus than S. monacanthus. A higher aggressiveness component of lesion size development on S. undatus stems by isolates from S. monacanthus was recorded suggesting a possible directional selection of highly aggressive N. dimidiatum in this host. This is the first population study on the phenotypic traits and the genetic structure of N. dimidiatum. Valuable inputs for further study of the pathogen are provided, which may help inform the design of management options for stem canker disease of dragon fruit.