European Journal of Plant Pathology最新文献

A nematological survey was conducted between 2021 and 2022 in banana fields distributed in two major banana-producing regions in the western coast of Syria. As a result, six populations of Xiphinema spp. identified as X. diffusum, X. pachtaicum, X. simile, X. vuittenezi and X. zagrosense were isolated from the rhizosphere of banana plants (Musa sp.) and characterized using morphological and molecular data based on two rRNA genes (D2–D3 expansion segments of the 28S, and ITS fragments) and partial region of the cytochrome oxidase I gene (COI mtDNA) sequences. Moreover, the molecular identification of the endosymbionts of these populations was also performed using the complete 16S rDNA gene. The phylogenetic relationships of the recovered species of nematodes and respective endosymbionts were reconstructed. Candidatus Xiphinematobacter sp. (OR196969; OR196971) and Ca. Xiphinematobacter sp. (OR196970) were detected in X. diffusum and X. simile, respectively, and clustered together with other Ca. Xiphinematobacter sp.A and sp.I respectively. To our knowledge, this is the first report of X. diffusum, X. simile, X. vuittenezi and X. zagrosense parasitizing banana in Syria, extending the geographical distribution of these species within the Mediterranean Basin.

Brazil is one of the largest melon producers worldwide, with its northeast region contributing 96% of the national production. However, fruit quality has been affected by diseases, recently associated with different Fusarium species, which have caused significant losses. The chemical product Imazalil is the most used to control post-harvest diseases in melons in Brazil, however, it is in the process of being banned. Furthermore, the market is increasingly demanding about food and environmental safety, increasing the need to search for alternative methods. From this perspective, this study aimed to evaluate the effect of thermotherapy on the management of rot caused by Fusarium species in Galia melons. Six times of immersion of the fruits in hot water at 58 ºC (0, 30, 60, 90, 120, and 150 s) and one chemical treatment (Imazalil fungicide) were evaluated for each species of Fusarium evaluated (F. falciforme and F. sulawesiense). The severity of the disease in fruits subjected to heat treatment after 90 s did not differ from chemical treatment, indicating that thermotherapy treatment can be used as an alternative to Imazalil. Thermotherapy also maintained the firmness of the fruits and increased the activity of peroxidase and polyphenol oxidase enzymes, increasing the fruits shelf life and activating defense pathways. Therefore, thermotherapy, at the temperatures and times evaluated, is recommended in the management of melon rot caused by Fusarium species.

Management of late blight relies on the use of fungicides and potato varieties which have been associated with loss of efficacy over time. Baseline survey and field studies were conducted to evaluate the effects of fungicide formulations and potato varieties in managing late blight and subsequently on net farm income improvement. Four fungicides formulations (Infinito® (Fluopicolide 62.5g L⁻¹ + propamocarb 625 g L⁻¹), Milraz® (Propineb 700 g kg⁻¹ + cymoxanil 60 g kg⁻¹), Mistress 72® (Mancozeb 640 g kg⁻¹ + cymoxanil 80 g kg⁻¹) and Ridomil® (Metalaxyl 40 g kg⁻¹ + mancozeb 640 g kg⁻¹)), and varieties (Kenya Mpya, Shangi and Dutch Robijn) were evaluated. Survey results revealed that the majority (78%) of the farmers selected varieties to grow based on market dynamics as compared to seed availability (18%), disease resistance (12%) and other factors (8%). The most widely and least used fungicides were Ridomil® (28.8%) and Infinito® (1.7%) respectively. Late blight significantly reduced crop growth (height and stem count) and yield in the unprotected plots in Shangi and Dutch Robijn, but no effect was observed in K. Mpya. Mistress® suppressed blight symptoms by 54%, while Milraz® (lowest effects) reduced the disease by (43%). In unprotected plots, disease severity on K. Mpya was below 1%, while in Shangi and Dutch Robijn varieties, it was 60 and 78% respectively. Reduction in disease by Mistress® resulted in higher yield (30.70 t ha⁻¹) as compared to the unprotected plots (9.25 t ha⁻¹). Maximum yield (28.56 t ha⁻¹) was obtained from K. Mpya, while Dutch Robijn, had the lowest observed yield (20.70 t ha⁻¹) in protected plots. Yet, the highest cost benefit ratio (CBR) was recorded in unprotected plots with K. Mpya. The smallest CBR (1.55) was observed on plots where Milraz® was applied on Dutch Robjn. Results of this study show that, the use of fungicides reduced late blight and improved yield of potato substantially, but the efficacy varied with fungicide formulation and potato variety. However, the use of resistant variety was effective in managing late blight hence a useful tool for minimizing fungicide applications. Therefore, use of resistant variety could enhance a healthy biodiversity and at the same time maximize food production.

Citrus reticulata Blanco shows substantial fruit drop due to diverse environmental factors leading to agricultural waste. However, such waste can be utilized as a safe and cheape source of botanical fungicide. The present work aimed to evaluate the antifungal potential of C. reticulata fruits dropped in June against Fusarium fujikuroi Nirenberg causing foot rot disease in rice as a natural and eco-friendly fungicide. The methanol extract of dropped citrus fruits was prepared by Soxhlet extraction and was further fractionated by column chromatography using petroleum ether, dichloromethane, ethyl acetate, methanol, ethanol and distilled water as solvents. Among all the treatments, the ethyl acetate fraction exhibited the maximum antifungal potential against F. fujikuroi having the least median effective dose at 650 µg/ml. The fraction (1500 µg/ml) showed significantly less disease incidence than the untreated plants in the nursery and transplanted plants of basmati rice cultivar Pusa Basmati 1121 during the kharif seasons 2021 and 2022. The fraction also caused a significant increase in cell constituents release in F. fujikuroi as compared to the control. Scanning electron microscopy analysis also showed that the treated hyphae were shrunken and broken at several points. This finding suggests that the ethyl acetate fraction might act on the fungal cell membrane leading to loss of cell membrane permeability that ultimately leads to cell death. GC–MS analysis of the fraction showed the presence of 3',4',5,6,7,8–hexamethoxyflavone (29.58%), 2-methoxy-4-vinylphenol (22.41%) and 4',5,6,7,8–pentamethoxyflavone (16.78%) as major compounds. Molecular docking of these major compounds with α-β-tubulin (PDB Code: 4FFB) revealed a binding score in the range of -6.1 to -5.3 kcal/mol respectively. Hence, the dropped citrus fruits which are generally discarded as waste may be used as botanical fungicides to control foot rot disease in rice.

Seed coating is an effective method for delivering beneficial microorganisms to the soil. Additionally, coated seeds are protected against pathogens or microbial contaminants during storage. This work aimed to evaluate the effect of seed coating with the beneficial fungus Trichoderma koningiopsis against fungal contaminants of sweet sorghum (Sorghum bicolor (L.) Moench) during storage. Sorghum-treated seeds with three concentrations of Trichoderma koningiopsis were stored at two temperatures (5 °C and 18 °C) over 12 months to evaluate physiological-, and sanitary quality of seeds. The concentrations of the most prevalent contaminant fungi Diaporthe melonis, Curvularia lunata and Penicillium polinocum were monitored. The viability of Trichoderma koningiopsis was evaluated every three months and correlated with the seed quality variables. The results indicate that beneficial fungi can protect seeds against fungal contamination during storage avoiding the application of a chemical fungicide. The coating procedure did not affect the seed germination over the 12 months of storage.

The effects of mineral composition (N, P, K, Mg, Fe, Cu, and Zn) against fire blight caused by Erwinia amylovora, the most devastating disease of pome fruits, was investigated in pear. Due to the transport physiology of minerals, the leaf contained higher concentrations of every mineral analyzed, especially macro-minerals (N, P, K, and Mg) compared to the fruit. Minerals obtained from the leaves were not statistically correlated with resistance to fire blight, however all the minerals examined in the fruit, except for K, were found to be significant. Increased P and Mg concentrations were associated with disease resistance, while N, Zn, Fe, and Cu were associated with susceptibility. Nitrogen-causing susceptibility exerted 61% of this impact through itself directly and was sharply distinguished from other mineral compounds. Furthermore, the indirect effect of nitrogen on disease susceptibility through Cu (39%), Zn (33%), and Fe (30%) was even higher than the direct effect of these minerals (21%, 24%, and 29%, respectively). The direct effects of P (13%) and Mg (10%), which are associated with an increase in resistance, were lower than the indirect effects (19% and 29%, respectively) due to their negative correlation with nitrogen, showing that the main effect of these minerals was in suppressing the negative effects of nitrogen on susceptibility by maintaining mineral balance.

Compost teas are watery fermented extracts with proven suppressive effects against plant pathogens. Compost teas were prepared from six different compost sources and assayed for in vitro effects against Botrytis cinerea growth. In vivo, weekly foliar application of compost teas on tomato plants and a tomato leaflet trial with undiluted and 10 × diluted teas were conducted to assess effects on grey mould caused by B. cinerea. Results showed that all tested compost teas inhibited B. cinerea growth when unsterilized. Heat- and cold-sterilization of compost teas reduced or eliminated inhibitory effects, suggesting that the presence of microorganisms is essential for inhibitory efficacy. When used as foliar sprays, bovine manure (BOV), shrimp (SHR), and garden-leaves-straw (GLS) compost teas effectively reduced disease severity for six weeks. In leaflet trials, BOV, GLS, and garden waste (GAR) compost teas caused the greatest delay in grey mould lesion expansion. Moreover, BOV, GLS, and, in particular, SHR compost teas were equally effective in undiluted and diluted form. Microbial characterization showed varying microbial compositions across all compost teas, with notably large populations of fungi or oomycetes and Pseudomonas spp. in GLS. There was no clear relationship between the source of compost (manure, other animal by-product, solely plant-based) and efficacy against grey mould. Results also indicate that the abundance of microbial populations and subpopulations did not correlate with the inhibitory effects of the teas. The diversity of microbial populations or the presence of particular microbial species is more likely to be a determining factor of compost tea efficacy.

This study set out to assess the antagonistic activities of isolated marine and endophytic Trichoderma in controlling rice blast and brown spot diseases in a field trial. All selected Trichoderma strains were fast-growing and able to grow over the rice pathogens tested within 4 days in dual tests. Twelve marine and endophytic Trichoderma strains were evaluated for their antagonistic activities against rice blast and brown spot diseases under greenhouse conditions. Five strains that displayed significant biocontrol activities against both diseases were selected, and their antagonistic activities were assessed under field trials in rice var. KMDL 105 in both their fresh and dry formulations. The results showed that the fresh formulations of all Trichoderma exhibited higher disease control performance than did the dry ones. Among the Trichoderma tested, the application of a fresh formulation of endophytic T. harzianum KUFA0405 showed the most effective biocontrol activity in suppressing leaf and neck blast diseases by 57.19 and 60.35%, respectively, while its dry formulation resulted in lower activity against blast disease, resulting in 51.26 and 46.66% disease reduction on leaf and neck blast diseases, respectively. Not only did endophytic T. harzianum KUFA0405 show the best biocontrol activity against the disease, but it also resulted in increasing the rice yield to 226 and 218 kg/ Acre when applied in fresh and dry formulations, respectively, compared with the control treatment, which resulted in a rice yield of only 158 kg/ Acre. Meanwhile, the application of endophytic T. harzianum KUFA0406 showed the most effective biocontrol activity in suppressing brown spot disease, causing a 39.23% and 29.64% disease reduction when applied as fresh and dry formulations, respectively, and increasing the rice yield up to 257 and 244 kg/ Acre when applied in fresh and dry formulations, respectively, compared with the control treatment, which resulted in a rice yield of only 184 kg/ Acre.

Abstract

Leaf rust caused by Puccinia triticina Eriks. is one of the yield constraining diseases of wheat. It is prevalent in almost all wheat growing areas of the world. Durable leaf rust resistance conferred by integration of slow rusting and effective major genes is the best strategy to combat this disease. In the present study a slow rusting gene, Lr34 was transferred into a heat tolerant wheat variety BRW 934 using marker-assisted back crossing. The BRW 934 was found highly susceptible to several Indian pathotypes of P. triticina including 12–2, 77–1, 77–5, 77–7, 77–8, 77–9, 77–10 and 104–2. The selection of the Lr34 gene was carried out using STS (sequence tagged site) marker csLV34. BC₁F₁ plants carrying Lr34 gene showed leaf rust scores ranging from 5 to 20MR and rust score in the BRW 934 progenies without the Lr34 gene were 30S-100S. Presence of the Lr34 gene significantly reduced disease severity in the progenies. Maximum recovery (87.5%) of the recurrent parent genome was obtained in plant number 16 and 30 in the BC₁F₁ generation. These findings indicated that the Lr34 gene can be effectively used in developing leaf rust resistant wheat lines for the Eastern-Gangetic plains.

Abstract

The application times and doses of fresh and dry formulations of Talaromyces tratensis KUFA 0091 were evaluated for their antagonistic activity in controlling mango diseases, anthracnose and stem-end rot diseases, under field conditions on two mango cultivars—namely, Nam Dok Mai Si Thong and Nam Dok Mai No. 4. The results show that three applications result in significantly more reduced disease severity than two and one applications. However, a high dose of the fresh formulation at 10⁸ spores/ mL of the antagonistic fungus resulted in higher antagonistic activity in controlling mango diseases than the dry formulation and lower doses in both mango cultivars. Treatment of three applications at the flowering, fruit-setting, and fruit-developing stages of the fresh formulation at 10⁸ spores/ mL had the best disease reduction at 80%–87%, followed by the dry formulation, which caused 75%–78% disease reduction. Meanwhile, the three applications of fresh and dry formulations at 10⁶ spores/mL also displayed significant biocontrol efficacy of 70%–79% disease reduction. Its culture filtrate at 50% completely inhibited the spore germination of the anthracnose pathogen. The dry formulation also showed high efficacy on post-harvest disease in mango fruits. Moreover, the antagonistic fungus showed comparable efficacy with fungicides at a label rate with propineb (1,750 ppm), azoxystrobin (250 ppm), and mancozeb (1,600 ppm). The results indicate that this fungus can act as an effective biological control or be combined with fungicides for integrated mango disease management.