European Journal of Plant Pathology最新文献

Sprinkler irrigation systems can release ascospores of Venturia inaequalis, the cause of apple scab, from infected leaves on the ground under conditions unsuitable for infection, and thus reducing the primary inoculum. Under-canopy irrigation was carried out for two hours in the middle of the day over overwintered apple leaves heavily infected with scab, either in a wind-protected enclosure or in a wind-exposed orchard. Ascospores were captured with rotating-arm spore traps at heights ranging from 0.3 m to 3.0 m above the ground. Ascospores dispersed above the irrigated layer and were detected at all heights above the sprinklers. Wind played a critical role in spore transport, evident from the set-up where wind interference was minimised by a wind fence, resulting in higher airborne spore numbers across all measured heights compared with the orchard exposed to unrestricted wind conditions. Furthermore, vertical temperature gradients significantly correlated with spore distributions, particularly where negative gradients at heights between 0.3 m and 0.05 m and positive gradients at heights between 1.0 m and 0.3 m led to spore retention within the irrigated zone. The findings highlight that ascospores, dispersed above the irrigated layers, could settle on susceptible tissues. It thus becomes imperative to ensure a rain-free period of at least 24 h post-irrigation and, if a rainfall shortly occurs after irrigation, the application of curative fungicides becomes essential following unexpected rain. Reliable weather forecasts are therefore crucial in determining the effectiveness of under-canopy irrigation to reduce apple scab incidence.

In Poland, red deer, roe deer and elk cause great damage to pine stands, and pine is the predominant forest-forming tree species in Polish forests. Pine seedlings planted adjacent to agricultural fields face heightened risk of damage from nocturnal foraging by game animals, which retreat to forested areas during the day. This damage creates openings for fungal entry, particularly by concerning plant pathogens, such as Fusarium species, which are prevalent in agricultural settings. This study aimed to analyze the mycobiome of pine seedlings damaged by forest animals, focusing on the presence of concerning pathogens in infested pine seedlings collected from ten forest plantations at various distances from rural areas. Samples of pine seedlings bitten by forest animals were taken from 10 forest plantations at different distances from rural areas. Selected diversity indices were determined to compare the fungal populations. Mycological analysis of the gnawed pine shoots using culture and qPCR methods revealed 746 fungal colonies. The most frequently isolated species were: Fusarium avenaceum, Alternaria alternata, Botrytis sp., Cladosporium cladosporioides, representatives of the genus Penicillium, Rhizopus nigricans and Fusarium oxysporum, which were found in samples from all study plots and are thus ubiquitous. Species that are typical pathogens of agricultural crops, such as Fusarium avenaceum, F. culmorum, F. poae, F. sporotrichioides and F. tricinctum, were also isolated from damaged seedling tissue in forest plantations neighbouring agricultural fields. Spearman’s rank correlation analysis showed that the importance of secondary pathogens, represented by species of the genus Fusarium, decreased with increasing distance from agricultural fields, while the importance of primary pathogens increased. Younger pine seedlings exhibited lower species diversity and a higher prevalence of specific secondary pathogen species, coupled with heightened susceptibility to infection compared to older seedlings when subjected to tissue damage by forest animals. These findings underscore not only variations among plantations in proximity to agricultural fields but also suggest potential inter-land spread of fungi, emphasizing the need for integrated management strategies across agricultural and forestry domains.

The bacterium Xanthomonas fragariae is the causative agent of angular leaf spot (ALS) of strawberry, a Regulated Non-Quarantine Pest in Europe (EPPO A2) for plant propagation material. Field experiments were conducted to explore if X. fragariae is dispersed through the air during trimming ALS-diseased strawberry plants with dry or wetted leaves. Trimming the leaves led to dissemination of leaf fragments to the nearby surroundings. A sharp decrease in the amount of leaf fragments within the first 5 m distance downwind from the strawberry plants was found. Furthermore, air quality monitors demonstrated that during trimming 0.5 – 10 μm sized particles were ejected into the air, resulting in short periods with increased particle densities 45 cm above ground level, which could be detected at least 50 m downwind. At this height X. fragariae was detected by means of air samplers, as evidenced with a combination of dilution-plating and TaqMan assays, at 25 m distance downwind from ALS-diseased plants. A sharp decrease in the density of X. fragariae colony forming units (cfu) within the first 10 m distance from the source plants was found. The densities of X. fragariae cfu were strongly associated with the particle densities. Results indicate that during trimming leaves of strawberry propagation crops with ALS-diseased plants there is a considerable risk of deposition of airborne X. fragariae inoculum on nearby nursery beds. Whether this airborne inoculum can result in infections is discussed.

The genus Xiphinema Cobb, 1913 belongs to the family Longidoridae and consists of approximatelly 280 described species of plant-root ectoparasites. They occur on all continents except Antarctica and many species are important pests of crops, harming plants either by direct parasiting or by vectoring of nepoviruses. Due to their economic importance, several species were subjected to regulations aimed to limit their global spread. Moreover, the use of molecular techniques allowed to confirm the occurrence of cryptic species within the genus. In this paper we describe Xiphinema cryptocostaricense sp. nov., which constitutes the first instance of cryptic speciation within the family Longidoridae from South America. In terms of morphology this species is characterised by the body measuring 2.00–2.35 mm; lip region detached from the body outline only by a shallow constriction; odontostyle 129–135 µm long; V = 34.0–36.6; anterior branch of the genital tract largely reduced; tail short, almost hemispherical; lack of males and presence of four juvenile stages. This species is also characterised using molecular markers D2-D3 expansion domains of 28S rRNA, ITS1 rRNA and partial cytochrome oxidase c subunit 1 gene sequences. Based on morphology, this species is indistinguishable from X. costaricense Lamberti and Tarjan (Nematologia Mediterranea, 2, 1–11 1974). Additionally, a nomenclature remark is given- the name X. cryptocostaricense sp. nov. has been created by adding prefix ‘crypto’ to an already existing name of species. The advanatage of this approach is that it immediately points to which species it is cryptic to. Finally, new data regarding the second species, X. seinhorsti are given, including a first report of this species outside the place of its original description, data on molecular markers and morphology, including the first description of the J1 and J2 stages.

Radish, considered a globally important crop, faces a severe threat from Alternaria blight. This pervasive and highly damaging disease causes black spots and blight on leaves in field conditions, resulting in reduced yield and seed quality. The study aimed to evaluate the antifungal potential of different wild botanicals against the Alternaria leaf blight pathogen through in vitro and in vivo studies and to analyze the phytochemicals using Gas Chromatography-Mass Spectrometry (GC–MS).

Among the fifty botanicals screened at 10% concentration against the pathogen, the aqueous extracts of Hemidesmus indicus, Lippia alba, Chromolaena odorata, and Solanum violaceum displayed the highest mycelial inhibition. Further in vitro evaluations of these four botanicals at different concentrations (2.5%, 5.0%, 7.5%, 10.0%, and 12.5%) revealed that at a 12.5% plant extract concentration H. indicus and L. alba exhibited the most effective inhibition of 82.96% and 76.60%, respectively, followed by C. odorata (71.93%) and S. violaceum (63.53%). Based on the promising in vitro results, these botanicals were assessed in pot experiments at 12.5% concentration. Among the four botanicals, the highest percentage of disease reduction was observed with H. indicus and L. alba, with 69.79% and 60.44%, respectively. Overall, the botanicals effectively reduced disease severity while increasing radish yield. GC–MS analysis of the phytochemicals revealed that the botanicals are composed of various bioactive compounds such as phenolics, flavonoids, saponins, and volatile compounds, which are known to exhibit antimicrobial activities.

This study emphasizes the potential of botanicals as a natural alternative for managing fungal diseases, offering resilient and sustainable approaches to safeguard crops from destructive fungal infections.

Sugarcane streak mosaic is an emerging viral disease caused by sugarcane streak mosaic virus (SCSMV) recently reported in Ivorian sugar production areas. A 5-year study was performed to determine the spatial distribution, prevalence and severity of SCSMV on commercial varieties in two of the three sugarcane production basins of Côte d'Ivoire. In Zuénoula, 104 plots were evaluated between 2018 and 2021. In Borotou-Koro, 72 plots were evaluated between 2019 and 2022. Disease prevalence and severity were assessed using a 0 to 4 rating scale based on the percentage of symptomatic leaf area. In Zuénoula, overall disease prevalence was 98% in 2018, 100% in 2020 and 98% in 2021. Varieties M1400/86, M2593/92, R570 and SP711406 were monitored during the three years. M1400/86 and M2593/92 showed a moderately susceptible profile, whereas R570 was susceptible to moderately susceptible and SP711406 was susceptible. In Borotou-Koro, overall disease prevalence was 21% in 2019, 48% in 2020 and 61% in 2022. Varieties Co449, M1400/86, R570 and SP711406 were monitored during the three years. Co449 remained moderately susceptible throughout the monitoring, while M1400/86, R570 and SP711406 varied from partially resistant to moderately susceptible. This study showed that SCSMV is highly prevalent in the Zuénoula sugar complex and is rapidly spreading in the Borotou-Koro complex. In this context, varieties showed either a stable or increasing susceptibility profile. In vitro regeneration permitted significant reduction in prevalence and severity but efforts must be maintained to achieve higher levels of resistance.

Fusarium wilt of banana (FWB), caused by soilborne Fusarium lineages, is a major global threat to the cultivation of bananas. In addition to persistent chlamydospores, weeds are a reservoir of the causal agents. However, it remains unclear whether other Zingiberales species, which are grown in the same geographic regions, also can serve as hosts for strains that cause FWB. Greenhouse assays were conducted to investigate whether a Race 1 strain (pathogenic to Gros Michel banana) or Tropical Race 4 (TR4) (pathogenic to a plethora of banana varieties, including Cavendish bananas) can infect three Heliconia species, two ornamental banana species or Musa textilis (abacá). Heliconia latispatha, Musa balbisiana, and Musa coccinea displayed external symptoms after inoculation with TR4, while inoculation with Race 1 caused symptoms in H. latispatha, H. psittacorum, M. coccinea, and M. velutina. Isolates were recovered from symptomatic and asymptomatic plants and were subsequently characterized and used to inoculate Gros Michel and Cavendish banana plants. They caused the typical FWB symptoms in these varieties, and the scores for discolored rhizome area were similar to those caused by the Race 1 and TR4 reference strains. These data call for a revision of the race nomenclature of FWB pathogens and adjustment of the current containment protocols.

Bacillus siamensis strain B30 was isolated from the rhizosphere of faba bean and molecularly identified using the 16S rRNA (Acc# OQ878652) and rpoB (Acc# OR061338) genes. Under greenhouse conditions, the application of B30, whether through soil inoculum or foliar application of its culture filtrate, significantly promoted growth and triggered systemic resistance against bean yellow mosaic virus (BYMV) infection in faba bean. As a result, the disease severity and viral accumulation levels were significantly reduced, by about 64% and 88%, respectively, for foliar application treatment. Furthermore, B30 treatments resulted in significant elevations in antioxidant enzymes such as catalase (CAT), ascorbate peroxidase (APX), polyphenol oxidase (PPO), and superoxide dismutase (SOD), as well as total chlorophyll content and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. A significant decrease in oxidative stress markers, namely hydrogen peroxide (H₂O₂) and malondialdehyde (MDA), was observed. These changes were accompanied by an upregulation of the transcriptional levels of pathogenesis-related genes. Furthermore, HPLC analysis revealed that most polyphenolic compounds were induced and accumulated in plants undergoing B30 treatments. GC–MS analysis revealed that the ethyl acetate extract of B30 culture filtrate contains significant amounts of 3,3-dimethylbutan-1,2-dione oxime; 3,4-dihdro-2H-1,5-(3"-T-butyl) benzodioxepine;1-nonadecene; 1-dodecanol, 3,7,11-trimethyl-; 1-docosene; 3,7,11-trimethyl-; pyrrolo[1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl)-; 2,2-dideutero octadecanal and á-sitosterol. The capability of B. siamensis B30 to boost faba bean growth and induce systemic resistance against BYMV infection implies that it could be utilized as a biocontrol agent, a viable and environmental approach to protecting faba bean plants from BYMV infection. This is the first time B. siamensis has been reported to have antiviral activity against plant viral infections.

Annual surveillance programs for the plant pathogenic bacterium Xylella fastidiosa are implemented in Europe as part of the preventive phytosanitary strategies enforced to face the emergence of the detrimental infections reported in olives in southern Italy. The programs include inspections and sampling of host plants by prioritizing those showing suspicious symptoms or those known to be highly susceptible to different strains and subspecies of the bacterium. In the framework of these programs numerous outbreaks have been unraveled, with several strains and subspecies found to infect a relatively large host range in France, Spain, Portugal and Italy. Here we report the results of an integrated surveillance approach implemented in the Apulia Region (southern Italy), where a conventional survey program on host plants is complemented by monitoring and testing for X. fastidiosa the insect vectors. In the framework of this program, bacterium-positive spittlebugs were intercepted in the Xylella-free area of the region, close to one of the most relevant Italian table grape production district. Such findings prompted further investigation to identify the bacterial reservoir in the host plants. Almond and grapevine were found to be the most frequently infected hosts, with infections caused by isolates of X. fastidiosa subspecies fastidiosa ST1. Investigations are ongoing to assess the extent and history of the outbreak, to assess and estimate the potential impacts, and define the best options for its containment.

Myrtle rust severely impacts guava cultivation. Currently, no rust-resistant guava cultivars have been found. This study aimed to identify rust-resistant plants from interspecific crosses of Psidium spp. using mixed models. Twenty-six crosses were evaluated in a greenhouse from September to October 2020. Inoculation was performed on young leaves and floral buds, and characteristics such as the latent period, infectious period, and area under the disease progress curve were measured to determine variance components and genetic parameters. Genotypic values were analyzed, and clones were ranked using mixed models. The genetic, environmental, and broad-sense heritability values varied from moderate to high. Mixed models revealed genetic variability for rust resistance. Clones from the Cv1 x Cv11 and Cv8 x Cv11 crosses were immune to rust. The P36 x P11 cross exhibited variability. The results of this study indicate the selection of clones that are immune and resistant to rust for use in future recombination.