Search Results (81)

English walnut (Juglans regia) is a species that is highly valued for the quality of its wood and the nutritional and nutraceutical properties of its fruit. A severe dieback of J. regia trees was observed recently in orchards located in three geographically distinct areas of Tuscany, central Italy. Symptoms included root and collar rot, necrosis of the under-bark tissue, bleeding cankers, stunted growth, and crown dieback. Four Phytophthora species were obtained from 239 isolates found on symptomatic J. regia individuals. They were identified, on the basis of macro-morphological (colony shape and texture), micro-morphometric (shape and size of oogonia, antheridia, oospores, sporangia, and chlamydospores) and molecular (ITS sequencing) characters, as P. gonapodyides, P. cactorum, P. citricola, and P. plurivora. Among these species, P. plurivora was the species isolated with overwhelming frequency from symptomatic tissue and rhizosphere soil, suggesting it to be the putative etiological agent. Pathogenicity assays were conducted on 20 cm long detached J. regia branches for a definitive establishment of disease causation. Severe symptoms (extended necroses) were exhibited by branches infected with P. plurivora, proving its pathogenicity and high virulence on this host. The other Phytophtora species produced negligible necroses around the inoculation site. P. plurivora was recovered from all the investigated orchards, providing evidence that it is quite widespread. This study highlights the growing threat posed by the polyphagous P. plurivora to walnut cultivation and the sustainable business it fuels in Europe, underscoring the need for integrated management strategies to mitigate its economic and ecological impacts. Full article

Fusarium culmorum is the causal agent of root rot and crown rot in soft wheat. The aim of this study was to investigate the control mechanism of Talaromyces pinophilus HD25G2 as a biocontrol agent against F. culmorum. This involved the isolation and molecular identification of Fusarium and Talaromyces strains from soft wheat. The assay included the inhibition test of F. culmorum mycelial growth on potato dextrose agar and soft wheat media at two water activity values (0.98 and 0.95), its production of mycotoxins, and the fungal cell wall-degrading enzymes implicated in the antagonistic effect of T. pinophilus. The results showed that T. pinophilus and its extract free of cells reduced the growth of F. culmorum by over 55%. Interestingly, the T. pinophilus HD25G2 showed high chitinase, protease, and cellulose production on solid media. In addition, chitinolytic and proteolytic activities were estimated at the values of 1.72 ± 0.02UI and 0.49 ± 0.01UI, respectively. However, the mycotoxin evaluation assay revealed that F. culmorum HD15C10 produced zearalenone (ZEA) and the biocontrol agent enhanced its production, but the early inoculation of T. pinophilus, before F. culmorum growth onset, inhibited 100% its growth and, therefore, prevented the presence of ZEA. Hence, this strain can be proposed as a biocontrol agent against F. culmorum, and it can be further investigated for biocontrol of Fusarium root and crown rot in vivo. Full article

Wheat (Triticum aestivum L.) is a crucial global food crop. The intensive crop farming, monoculture cultivation, and impact of climate change affect the susceptibility of wheat cultivars to biotic stresses, mainly caused by soil fungal pathogens, especially those belonging to the genus Fusarium. This situation threatens yield and grain quality through root and crown rot. While conventional chemical fungicides face resistance issues and environmental concerns, biological alternatives like seed priming with natural metabolites are gaining attention. Polyamines, including putrescine, spermidine, and spermine, are attractive priming agents influencing plant development and abiotic stress responses. Spermine in particular shows potential for in vitro antifungal activity against Fusarium. Optimising spermine concentration for seed priming is crucial to maximising protection against Fusarium infection while ensuring robust plant growth. In this research, we explored the potential of the polyamine spermine as a seed treatment to enhance wheat resilience, aiming to identify a sustainable alternative to synthetic fungicides. Our findings revealed that a six-hour seed soak in spermine solutions ranging from 0.5 to 5 mM did not delay germination or seedling growth. In fact, the 5 mM concentration significantly stimulated root weight and length. In complementary in vitro assays, we evaluated the antifungal activity of spermine (0.5–5 mM) against three Fusarium species. The results demonstrated complete inhibition of Fusarium culmorum growth at 5 mM spermine. A less significant effect on Fusarium graminearum and little to no impact on Fusarium oxysporum were found. The performed analysis revealed that the spermine had a fungistatic effect against the pathogen, retarding the mycelium growth of F. culmorum inoculated on the seed surface. A pot experiment with Bulgarian soft wheat cv. Sadovo-1 was carried out to estimate the effect of seed priming with spermine against infection with isolates of pathogenic fungus F. culmorum on plant growth and disease severity. Our results demonstrated that spermine resulted in a reduced distribution of F. culmorum and improved plant performance, as evidenced by the higher fresh weight and height of plants pre-treated with spermine. This research describes the efficacy of spermine seed priming as a novel strategy for managing Fusarium root and crown rot in wheat. Full article

Oregano (Origanum vulgare) cultivation is of great economic importance in Peru. Tacna stands out as its main producer. However, the presence of phytopathogenic fungi represents a challenge for its production. This study aimed to characterize both the morphological and molecular levels of the causal agent of crown and root rot in a crop field in the Camilaca district, Candarave, Tacna. To this end, systematic sampling was carried out using the five-gold method, collecting plants with typical symptoms. Fungi were isolated from diseased roots and characterized using macroscopic and microscopic morphological analysis as well as sequencing and multilocus phylogenetic analysis (ITS, 28S, HIS3, TEF1, TUB2). In addition, pathogenicity tests were performed on healthy plants to confirm the infectivity of the isolates. The results demonstrated that root rot was caused by a complex of phytopathogenic fungi through phylogenetic analysis of Dactylonectria torresensis, Fusarium oxysporum, F. iranicum, and F. redolens. These findings represent the first report of these species as causal agents of oregano root rot in Peru, highlighting the need for integrated management strategies that reduce the economic impact of these diseases and contribute to the sustainability of the crop in key producing regions such as Tacna. Full article

Root and crown rot in strawberries caused by Neopestalotiopsis rosae (N. rosae) results in yield losses of approximately 70%. The main method of control is based on the application of fungicides; however, the excessive use of these products can induce resistance by pathogens to the active ingredients. The use of secondary metabolites is an alternative to disease management. Usnic acid (UA), a secondary metabolite produced by lichens, has shown antimicrobial and antifungal activities that could be useful for the management of phytopathogens, particularly the (+) enantiomer. To provide alternatives to fungicides, the potential of UA as an alternative for N. rosae management was evaluated under in vitro and in vivo conditions. Using the “poisoned medium” technique, concentrations of 0 (UA0), 100 (UA1), 200 (UA2), and 400 (UA4) µg/mL UA at a dose of 2.5 mL/L PDA were evaluated on N. rosae mycelial growth and the number of spores. The UA at 400 µg/mL exhibited a fungistatic effect, reducing the mycelial growth of isolates of N. rosae in 50–60%. In the in vivo assay, sprayed UA (400 µg/mL) reduced hydrogen peroxide (48.59%) and malonaldehyde (77.62%) contents in “Albion” strawberry seedlings inoculated with 466 and FREC2 strains, respectively. These findings suggest that UA could be a potential tool for N. rosae management and could help mitigate the oxidative stress induced by infection. However, field trials are required to evaluate and validate this response. Full article

In recent years, severe decline and mortality events have been observed in holm oak (Quercus ilex L.) ecosystems in different Italian regions, including Puglia (southern Italy). Given the landscape and ecological relevance of holm oak forests in Apulia, a study was conducted to identify the causal agents related to this complex disease syndrome. The surveys, conducted in winter 2024 in three different woodlands, revealed the widespread occurrence of mature holm oak trees showing sudden death, crown thinning, shoot and branch dieback, sunken cankers, and root rot symptoms. Isolations performed from symptomatic samples collected from both stem and small roots yielded fungal and fungal-like colonies representing two distinct families: Botryosphaeriaceae and Peronosporaceae. Analysis of morphological and DNA sequence data allowed us to identify six distinct species, including Diplodia corticola and D. quercivora (Botryosphaeriaceae), Phytophthora cinnamomi, P. multivora, P. psychrophila, and P. asparagi (Peronosporaceae). For P. asparagi and P. psychrophila, isolated for the first time from declining holm oak trees in Italy, Koch’s postulates were satisfied by inoculating 1-year-old seedlings at the collar in controlled conditions. Thirty days after inoculation, all plants showed the same symptoms observed in the field. Overall, the data obtained highlights the co-occurrence of multiple Botryosphaeriaceae and Phytophthora species on declining holm oak trees and the discovery of a new haplotype of Diplodia quercivora. Full article

Phytopythium vexans is a plant pathogen responsible for a variety of destructive diseases in crops worldwide. This includes patch canker, damping-off, root, and crown rots in economically important crops, such as apple, pear, grapevine, citrus, avocado, and kiwi. The pathogen has a global distribution, and a recent report confirmed its presence in southern Ontario, Canada. This study presents the first genome sequencing, assembly, and annotation of the Canadian P. vexans strain SS21. To explore how variation in secreted protein repertoires may relate to infection strategies and host adaptation, we compared the predicted secretome of SS21 with reference strains from Iran (CBS 119.80) and China (HF1). The analysis revealed that HF1 harbors a larger set of CAZymes, sterol-binding proteins, and predicted effectors, which may suggest broader adaptive potential. In contrast, strain SS21 appears to have adapted to a niche-specific strategy, with fewer necrosis-inducing proteins, glucanase inhibitors, and effectors, possibly indicating adaptation to specific hosts or ecological conditions. Comparative genome data highlight distinct evolutionary trajectories that may have shaped each strain’s infection strategy, with SS21 potentially serving as a robust additional reference for future studies on P. vexans biology and host interactions. While this analysis identifies key candidate effectors, gene expression studies are required to validate their functional roles in infection and host manipulation. Full article

Fusarium pseudograminearum (Fp) and soil salinity are two types of stress that interact in complex ways, potentially leading to more severe consequences on wheat growth and productivity. However, little is known about the colonization efficiency and the signal pathways of the beneficial Trichoderma longibrachiatum TG1 (TG1) in controlling wheat Fusarium crown rot caused by Fp, and enhancing wheat seedling growth under combined salinity and Fp stresses. Therefore, the present study aims to determine the colonization, phytohormone profile, and signaling pathway in TG1-treated wheat seedlings under salinity and Fp stresses. In a dual culture assay, TG1 exhibited a mycoparasitic effect on Fp growth by coiling, conidial attachment, and parasitism observed under fluorescent microscopy. In addition, TG1 colonized the outermost layers of the wheat seedling roots with biomass consisting of conidia and hyphae. Under 100 mM NaCl stress, the combined TG1+Fp-treated seedlings recorded a control efficacy of 47.01% for the wheat crown rot disease compared with Fp-alone-treated seedlings. The contents of indole-3-acetic acid (IAA), gibberellic acid (GA₃), abscisic acid (ABA) and jasmonic acid (JA) significantly increased by 72.16%, 86.91%, 20.04%, and 50.40%, respectively, in the combined TG1+Fp treatments, whereas the ethylene (ET) content decreased by 39.07% compared with Fp alone at day 14; and 5.07 and 2.78-fold increases in the expression of salicylic acid (SA) signaling pathway genes, such as pathogenesis-related protein 1 (PR1) and isochorismate synthase 1 (ICS1) genes were recorded respectively, in the combined TG1+Fp-treated seedlings compared with the control at day 14. Full article

Neopestalotiopsis spp. are emerging fungal pathogens associated with leaf spot, fruit rot, crown rot, and root rot in strawberries. Despite their endophytic lifestyle, global outbreaks of these pathogens have been reported over the past few years, causing severe economic losses in commercial strawberry production. Resistance has been reported against the chemical fungicides used to manage Neopestalotiopsis spp. This review comprehensively examines the epidemiology, biology, and infection mechanisms of Neopestalotiopsis spp. on strawberries. Recent advances in management strategies, including biological control agents and resistant strawberry cultivars, have also been highlighted. By integrating these approaches, this work aims to provide a foundation for sustainable management practices to mitigate the impact of Neopestalotiopsis spp. on strawberry production. Full article

A severe dieback of rosemary (Rosmarinus officinalis L.) plants was observed in a medicinal/culinary herb plantation in Casole d’Elsa, Siena, central Italy. Symptoms included stunted growth, crown desiccation, root rot, collar rot and internal tissue necrosis, strongly indicative of Phytophthora root and crown rot syndrome. Morphological and molecular identification (ITS and Cox1 sequencing) of strains isolated from symptomatic stems, roots and soil revealed the occurrence of two Phytophthora species: Phytophthora pseudocryptogea, which constituted 94% of isolates obtained from the stem, root apparatus and rhizosphere; and Phytophthora megasperma, which was not recovered from plant organs or tissue, being exclusively isolated from rhizosphere soil samples at a low isolation rate (6%). The pathogenicity of the obtained strains was assessed by inoculating eighteen-month-old R. officinalis plants in a soil infestation trial. Plants inoculated with P. pseudocryptogea strains died 10 days after artificial inoculation. P. pseudocryptogea was subsequently re-isolated from the roots of inoculated, symptomatic plants, thus fulfilling Koch’s postulates. Plants inoculated with P. megasperma strains were in good vegetative condition and did not show any visible symptoms, suggesting P. megasperma to be nonpathogenic. Artificial inoculation tests thus confirmed P. pseudocryptogea to be the aetiological agent responsible for the death of R. officinalis plants in the plantation under study. This is the first report of root, collar and crown rot caused by P. pseudocryptogea on R. officinalis in Italy. There is evidence that poorly drained soils and climate constraints facilitate the spread of this oomycete. These findings highlight the critical role of nursery trade in the introduction of Phytophthora species in agroecosystems and emphasize the need for more stringent control measures. Full article

Different Pestalotiopsis-like species have been reported in strawberry worldwide, as agents of leaf spot, root rot, and crown rot. The identification of Pestalotiopsis-like fungi is based on both molecular and morphological analyses to discriminate between species and clarify phylogenetic relationships. Recent studies have provided robust multi-locus analyses, which reclassified most Pestalotiopsis-like isolates associated with strawberry root and crown rot diseases as Neopestalotiopsis spp. Numerous disease outbreaks have been observed in strawberry fields in Italy in recent years, showing that Neopestalotiopsis is an emerging pathogen. A survey was conducted in Northern Italy during 2022–2023 to investigate the diversity and distribution of Neopestalotiopsis species. Morphological and phylogenetic characterization, based on ITS, tef1 and tub2, led to the identification of four species: Neopestalotiopsis rosae, N. iranensis, N. hispanica (syn. vaccinii) and N. scalabiensis. Based on our results from multi-locus phylogenetic analysis, N. hispanica and N. vaccinii were grouped in the same cluster; thus, they were confirmed to be the same species. Pathogenicity tests with representative isolates of each species were conducted on strawberry ‘Portola’ transplants. All isolates were shown to be wound pathogens in strawberry, causing crown rot, and were successfully re-isolated. Neopestalotiopsis rosae was confirmed to be the most dominant and virulent species associated with these symptoms, as well as the most dominant among the obtained isolates. To the best of our knowledge, this work represents the first report of N. scalabiensis being associated with the crown rot of strawberry in Italy and the first report of N. iranensis in association with the crown rot of strawberry worldwide. Full article

Strawberries are planted globally as an important crop. Fusarium oxysporum f. sp. fragariae (Fof), a haploid mitosporic, pathogenic fungus with obvious host specificity, is responsible for an economically devastating soil-borne disease seriously threatening strawberry. Fusarium oxysporum is distributed in soils worldwide and causes vascular wilt and root rot disease in over 100 plant species. However, the formae speciales of F. oxysporum commonly have a very narrow host range, often restricted to a single host plant species. We isolated and identified pathogenic F. oxysporum from diseased strawberry samples collected from different provinces in China. Further analysis showed that among the 55 F. oxysporum isolates, only 70.91% belonged to Fof, and the remaining 29.09% were named Fo. The mycelial growth of Fof was faster than that of Fo at 20, 30, and 35 °C. The sporulation ability of Fof was weaker than that of Fo, and Fof presented a significantly higher germination rate under high temperatures. Fof and Fo from strawberry were not pathogenic to tomato or cucumber plants, and Fof showed significantly higher pathogenicity on strawberry than Fo. To explore the pathogenic mechanism of Fof, we knocked out SIX10 in Fof. The mycelial growth rate of ΔFofSIX10 was significantly slower than that of the wild type, but there were no significant differences in spore production. The pathogenicity of ΔFofSIX10 to strawberry was significantly weakened, showing decreased severity of symptoms, indicated by root and crown rot, and wilt. Our research provides a basis for understanding the interaction between F. oxysporum and the host strawberry and the occurrence and management of Fusarium disease on strawberry. Full article

In Chile and worldwide, walnut (Juglans regia L.) production faces significant losses due to crown and root rot caused by the phytopathogen Phytophthora cinnamomi. Currently, control methods have proven insufficient or unfavorable for the environment, increasing the need for sustainable alternatives. This research evaluates nanoemulsions based on extracts of medicinal plants endemic to Chile to control P. cinnamomi in walnut crops. The methodology included an in vitro test to determine the effective inhibitory concentrations of three nanoemulsions (N80, N90, and N100) on the mycelial growth of the phytopathogen, a test on walnut plants under controlled conditions, and two field tests using concentrations between 300 and 500 ppm. The in vitro results showed that the nanoemulsions could inhibit 90% of mycelial growth at 80 to 100 ppm concentrations. In the field, the N90 nanoemulsion at 500 ppm significantly reduced disease symptoms preventively and post-inoculation, compared with the control. This research is the first to study the use of nanoemulsions from native Chilean plants to control P. cinnamomi, showing potential to reduce the use of synthetic fungicides, contributing to safer and more ecological phytosanitary management. Full article

Strawberry crown and root rot diseases are caused by soil-borne pathogens including Macrophomina phaseolina (Mp) and Verticillium dahliae (Vd). The symptoms caused by these pathogens are very similar and difficult to distinguish, and traditional culture-based detection methods are laborious, time-consuming, and slow in providing results. In this work, we developed a duplex PCR-NALFIA assay using two pairs of species-specific primers labeled at the 5′ end with different molecules for the simultaneous identification of Mp and Vd. For the NALFIA assay, a lateral flow device (LFD) for the detection of two analytes was used. The method was developed by single and duplex PCR (Mp, Vd, Mp + Vd) using increasingly complex biological systems: (i) DNA from pure cultures of the pathogens; (ii) DNA from artificially inoculated cut melon stems; and (iii) DNA from artificially inoculated strawberry plants cv. Aromas. The duplex PCR protocol was effective in detecting the two pathogens within melon tissues and provided good results with strawberry crown tissues only when the DNA samples were purified by removing the PCR inhibitors. The amplicons were used for both agarose gel electrophoresis (AGE) and NALFIA assays and demonstrated the greater sensitivity of the NALFIA assay (10 pg) for simultaneous detection of the two pathogens. Full article

In recent years, strawberry cultivation in Spain has been increasingly affected by new and re-emerging fungal diseases. The most significant emerging diseases in Spain include those caused by Neopestalotiopsis spp. Maharachch., K.D.Hyde & Crous and Fusarium oxysporum f. sp. fragariae Winks & Y.N. Williams. These pathogens are difficult to control due to their pathogenic variability (presence of pathotypes and/or races), the lack of knowledge about the susceptibility of the different cultivars, the limited availability of effective fumigants, and the absence of sufficient information about their sources of inoculum. Both pathogens can cause root and crown rot, leading to plant collapse and significant losses for strawberry producers. Several factors have contributed to the rise of these diseases in Spain: (i) the gradual ban on key soil fumigants has left the crop vulnerable; (ii) there has been a notable diversification in the origin of mother plants used in cultivation, with plants now sourced from various countries, increasing the risk of long-distance pathogen spread; (iii) the introduction of numerous new strawberry varieties, which exposes more genotypes to pathogenic infections; and (iv) changes in planting times, leading to younger and more vulnerable plants being exposed to heat stress, as well as an increase in disease susceptibility. Neopestalotiopsis spp. and Fusarium oxysporum f. sp. fragariae have also become major threats to strawberry crops worldwide, spreading through nursery plants and the movement of plant material. The latest research findings in Spain on both pathogens are highlighted in this manuscript. Full article