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1.
Sheila M. P. Andrade Guilherme R. Augusti Gabriel F. Paiva Heraldo R. Feksa Dauri J. Tessmann Franklin J. Machado Eduardo S. G. Mizubuti Emerson M. Del Ponte 《Plant pathology》2022,71(5):1152-1163
Wheat farmers rely on fungicides to protect fields against several foliar and flowering diseases, including Fusarium head blight (FHB). A range of active ingredients is used in isolation or in dual premixes that include a dimethylation inhibitor (DMI) or a quinone outside inhibitor (QoI) fungicide. Comprehensive information about fungicide resistance in F. graminearum is available for DMIs, while for QoIs the data are scarce. We characterized 225 strains obtained from two states in southern Brazil, Rio Grande do Sul (RS) and Paraná (PR), in relation to their response to two QoIs. The median EC50 (effective concentration leading to 50% inhibition of conidial germination) value for azoxystrobin (n = 25 isolates) was 2.20 μg/ml in the PR population and 4.04 μg/ml in the RS population. For pyraclostrobin (n = 50), the median EC50 was 0.28 μg/ml in the PR population and 0.24 μg/ml in the RS population. Evidence of cross-resistance could not be detected. Screening using a discriminatory dose (DD) for azoxystrobin in a larger number of isolates from PR (n = 75) and RS (n = 100) states allowed the detection of 50% and 28% sensitive strains, respectively. Using the DD for pyraclostrobin, 33% and 18.8% were classified as less sensitive in the PR and RS isolates, respectively. In RS, the frequency of less-sensitive isolates increased over time (2007–2011). No point mutation at any of the target spots (F129L, G137R, G143A) was detected. Our results represent an important step towards the establishment of a sensitivity profile for two of the most commonly used QoIs in commercial premixes targeting FHB control. 相似文献
2.
Nan-Nan Yuan Shu-Ning Chen Liu-Xiang Zhai Guido Schnabel Liang-Fen Yin Chao-Xi Luo 《European journal of plant pathology / European Foundation for Plant Pathology》2013,136(4):651-655
Monilia yunnanensis was recently identified as a new species causing brown rot of peach in China. Sterol 14α-demethylase inhibitors (DMIs) continue to be important in the management of brown rot of Monilinia spp. worldwide. Tebuconazole and triadimefon are two kinds of DMI fungicides that may be used for brown rot control in China. To establish the baseline sensitivity of M. yunnanensis to these two DMI fungicides, 203 M. yunnanensis single spore isolates were collected. Measurements of sensitivity to the two fungicides were based on inhibition of mycelial growth. For both fungicides, the sensitivity distribution was a unimodal curve, with an EC50 range (the effective concentration to inhibit mycelial growth by 50 %) of 0.0001–0.0644 μg/ml for tebuconazole and 0.2311–1.7477 μg/ml for triadimefon. The M. yunnanensis isolates were obtained from orchards where DMI fungicides have not been used for peach brown rot control, thus the fungicide sensitivity distribution established in this study can be considered as the baseline for monitoring the resistance development in M. yunnanensis once the DMI fungicides are used to control peach brown rot. 相似文献
3.
The apple rust mite Aculus schlechtendali (Nal.) (Acari: Eriophyidae), is a main pest in apple-growing areas in Ankara, Turkey, and chemical control applications have
some limitations. Entomopathogenic fungi have a potential for biological control of mites. In this study, an entomopathogenic
fungus, Paecilomyces lilacinus (Thom) Samson (Deuteromycota: Hyphomycetes), was first isolated from the mite cadavers on Japanese crab apple leaves and
pathogenicity of the fungus was observed in different inoculum densities and relative humidities. The pathogen caused up to
98.22% mortality of the mite population. The effects of some fungicides on the entomopathogenic fungus were determined in
in vitro studies. Carbendazim, penconazole and tebuconazole were the most effective fungicides on mycelial growth of P. lilacinus, with EC50 values under 3 μg ml−1. In spore germination tests, captan, mancozeb, propineb were the most effective fungicides, followed by tebuconazole, penconazole,
nuarimol and chlorothalonil. Sulphur could not inhibit the conidia germination totally at 5,000 μg ml−1. Copper oxychloride and fosetyl-al prevented conidia formation at concentrations above 1,000 μg ml−1. 相似文献
4.
Francisco J. Sautua Vinson P. Doyle Paul P. Price Alejandro Porfiri Paula Fernandez Maria M. Scandiani Marcelo A. Carmona 《Plant pathology》2020,69(9):1678-1694
Cercospora species cause cercospora leaf blight (CLB) and purple seed stain (PSS) on soybean. Because there are few resistant soybean varieties available, CLB/PSS management relies heavily upon fungicide applications. Sensitivity of 62 Argentinian Cercospora isolates to demethylation inhibitor (DMI), methyl benzimidazole carbamate (MBC), quinone outside inhibitor (QoI), succinate dehydrogenase inhibitor (SDHI) fungicides, and mancozeb was determined in this study. All isolates were sensitive to difenoconazole, epoxiconazole, prothioconazole, tebuconazole, and cyproconazole (EC50 values ranged from 0.006 to 2.4 µg/ml). In contrast, 51% of the tested isolates were sensitive (EC50 values ranged from 0.003 to 0.2 µg/ml), and 49% were highly resistant (EC50 > 100 µg/ml) to carbendazim. Interestingly, all isolates were completely resistant to azoxystrobin, trifloxystrobin, and pyraclostrobin, and insensitive to boscalid, fluxapyroxad, and pydiflumetofen (EC50 > 100 µg/ml). The G143A mutation was detected in 82% (53) of the QoI-resistant isolates and the E198A mutation in 97% (31) of the carbendazim-resistant isolates. No apparent resistance mutations were detected in the succinate dehydrogenase genes (subunits sdhB, sdhC, and sdhD). Mancozeb completely inhibited mycelial growth of the isolates evaluated at a concentration of 100 µg/ml. All Argentinian Cercospora isolates were sensitive to the DMI fungicides tested, but we report for the first time resistance to QoI and MBC fungicides. Mechanism(s) other than fungicide target-site modification may be responsible for resistance of Cercospora to QoI and MBC fungicides. Moreover, based on our results and on the recent introduction of SDHI fungicides on soybean in Argentina, Cercospora species causing CLB/PSS are insensitive (naturally resistant) to SDHI fungicides. Insensitivity must be confirmed under field conditions. 相似文献
5.
Rosalba Troncoso-Rojas Yolanda Corral-Acosta Alberto Sánchez-Estrada Raymundo García-Estrada Alfonso Aguilar-Valenzuela Javier Ojeda-Contreras Martín Ernesto Tiznado-Hernández 《Phytoparasitica》2009,37(5):445-451
The fungicidal activity of allyl-isothiocyanate (allyl-ITC), benzyl-isothiocyanate (benzyl-ITC) and a mixture of isothiocyanates
(allyl-ITC, benzyl-ITC, phenyl-isothiocyanate and 2-phenylethyl-isothiocyanate; MCIT), was tested in netted melon infected
with Alternaria alternata as, was the effect of these compounds on the postharvest quality. Fruits were inoculated with A. alternata and exposed to allyl-ITC, benzyl-ITC, or MCIT, at 0.25 and 0.5 mg ml−1 concentrations. A commercial fungicide, Captan (CF), was used as a positive control. The fruit was stored at 20°C and 92%
relative humidity for up to 8 days. Allyl-ITC and MCIT at both tested concentrations, significantly reduced Alternaria rot,
by 82.73% to 88.67%. None of the ITC treatments had a significant effect on weight loss, total soluble solids, titratable
acidity or pH. Fruits treated with 0.5 mg ml−1 of AITC were more firm than others. Treatment with allyl-ITC, benzyl-ITC, or MCIT appears to be a promising alternative to
synthetic fungicides for controlling postharvest diseases in netted melon. 相似文献
6.
Régis Oliveira Fialho Providence Moyo Paul Hendrik Fourie Fabrício Eustáquio Lanza Franklin Jackson Machado Lilian Amorim Geraldo José Silva-Junior 《Plant pathology》2022,71(7):1606-1618
Citrus black spot (CBS) symptom expression on sweet oranges has been reported to be affected by the fruit developmental stage and inoculum concentration in greenhouse conditions. However, there is little information concerning the period in which the fruit is susceptible in commercial orchards. This study assessed the influence of fruit age and inoculum concentration of Phyllosticta citricarpa on CBS intensity and fruit drop in the field. Two field trials were conducted in commercial ‘Valencia’ orchards in São Paulo state, Brazil. Fruit were inoculated from October (petal fall stage) to July (c.6.5 cm diameter), with 101, 103 and 105 pycnidiospores/ml. CBS symptoms and fruit drop were observed in higher levels for fruit inoculated from October to February than from March to July. In both trials, when fruit were inoculated 10 times from October to July or single-inoculated in November or December, high CBS severities of 11%–22% were observed and the proportion of fruit remaining on the tree was 48%–77%; in contrast, noninoculated fruit had severity below 1.1% and 90% remained on the tree. Inoculations in November or December of green fruit with 1.5–3.0 cm diameter using 105 pycnidiospores/ml were associated with higher CBS intensity and fruit drop and shorter incubation period than inoculations with lower concentrations. This work provides a better understanding of fruit stages and P. citricarpa inoculum concentrations most related to symptom expression and losses under natural conditions and may be helpful for improvement of CBS management in the São Paulo citrus belt. 相似文献
7.
Samira Santiago Librelon Fernanda Aparecida Castro Pereira Paula Furtado de Pádua Nathália Bottrel Maia Pereira Luanna de Barros Wanderley Gomes Rafael Pereira Lucas Fidelis Pereira Edson Ampélio Pozza Elaine Aparecida de Souza 《Plant pathology》2022,71(6):1431-1439
Angular leaf spot (ALS), an important disease of common bean (Phaseolus vulgaris), is caused by the fungus Pseudocercospora griseola. This pathogen has a wide genetic variability and, therefore, poses a challenge to integrated disease management. The use of resistant cultivars is difficult; hence, the application of fungicides has been a common practice in common bean cultivation. P. griseola strains were morphophysiologically characterized and their sensitivity to common fungicides used to control ALS was studied. The strains were evaluated for sporulation capacity and a representative sample of 34 strains was bioassayed to determine their sensitivity to commercial concentrations of five fungicides, namely pyraclostrobin, mancozeb, pyraclostrobin + metconazole, chlorothalonil and tebuconazole. Another sample of 29 strains was studied for conidial germination and dimensions. Sporulation capacity ranged from 0.88 to 27.67 × 104 conidia/ml and germination percentage ranged from 39% to 72%. The large differences among strains suggest a wide genetic variability among the strains. A wide variability in aggressiveness of P. griseola was observed, which has consequences for breeding programmes aimed at resistance. The behaviour of pathogen strains differed in every fungicide evaluated, even in a population that has not been under selection pressure in the field. These results confirm the need for further studies and may guide future research with this pathogen. 相似文献
8.
Hui Yin Jian-Bo Zhou Ya-Lei Chen Lu Ren Nan Qin Yan-Li Xing Xiao-Jun Zhao 《Plant pathology》2022,71(2):344-360
Quinoa panicle rot (QPR) is a novel disease that poses a significant threat to quinoa production in China. Typical symptoms on panicles include a film of pale pink, grey-white, or dark brown mould on the grains during the grain-filling stage. Furthermore, QPR causes quinoa grain discolouration, unfilling, and malformation. In total, 37 isolates were identified as belonging to three species: Trichothecium roseum (nine isolates), Alternaria alternata (12), and Fusarium citri (16) based on morphology, and phylogenetic and pathogenicity characterization. The present study shows for the first time that T. roseum, A. alternata, and F. citri are the pathogens responsible for QPR. An evaluation of the growth and germination rates revealed a significant difference among the three species, with T. roseum and F. citri isolates having higher fitness in warmer (25–30℃) and humid conditions (water activity ≥0.98). However, A. alternata preferred cooler (20–25℃) and more arid conditions, and germinated in a wide range of water activities (water activity of 0.90–1.00). Among the three species, T. roseum and F. citri are probably responsible for the pink and grey diseased grains in humid regions, and A. alternata for the black-brown diseased grains in arid regions. Pathogenicity tests showed that all three species could infect the quinoa panicles. The results of this study provide a basis for the recognition and management of QPR. 相似文献
9.
A technique is described for testing isolates of Septoria tritici from winter wheat for resistance to benzimidazole fungicides. Secondary spores from 23 isolates were tested on Czapek Dox V-8 agar amended with benomyl at 1–10 μg ml. Twenty-one isolates were recovered from eight crops in England in 1984 and two (PBI isolates) were obtained in 1973. Thirteen isolates, including both PBI isolates, were sensitive to benomyl at 1 μg ml?1 and nine were resistant at 10 μg ml?1. The remaining isolate had a low proportion (1:3.7 x 104) of resistant spores. The minimum inhibitory concentration for sensitive isolates was 0.2–0.4 μg ml 1 benomyl and for resistant isolates was more than 1000 μg ml 1. Benomyl-resistant isolates were cross-resistant to carbendazim, thiabendazole and thiophanate-methyl, but not to 12 other fungicides with different modes of action. The implications of these findings are discussed. 相似文献
10.
Green mould disease causes serious economic losses in Pleurotus ostreatus crops worldwide, including in Italy, where prochloraz is the only chemical fungicide allowed to control the disease. The effectiveness of the doses 0.01, 0.05, 0.25 and 1.25 μL L−1 (field dose) of prochloraz (Sponix Flow, 450 g L−1), against colony growth rate and spore germination of Trichoderma pleuroti, T. pleuroticola and T. guizhouense strains on wheat straw extract agar plates were evaluated. Complete inhibition of Trichoderma pleuroti and T. pleuroticola growth was shown by the field dose of prochloraz, and also by the 0.25 μL L−1 dose for T. pleuroti. Complete inhibition of spore germination occurred for all Trichoderma strains at field dose, and at 0.25 μL L−1 for T. pleuroti strains. In in vivo assays, the effect of prochloraz doses 0.05, 0.25 and 1.25 μL L−1 on colonization of straw substrate by T. pleuroti, T. pleuroticola and T. guizhouense inoculated at two spore densities (102 and 105 spores mL−1) immediately after P. ostreatus spawn was studied. Trichoderma pleuroti and T. pleuroticola were both responsible for green mould disease, whereas T. guizhouense was not pathogenic. Trichoderma pleuroti was more aggressive than T. pleuroticola. Prochloraz was effective against T. pleuroti at the field dose, and against T. pleuroticola at 0.25 and 1.25 μL L−1. The study on Trichoderma × Pleurotus interaction type showed that Trichoderma species were active against the mycelial growth of P. ostreatus by competition for space and nutrients, and neither hyphal interaction nor effect by volatile or nonvolatile metabolites occurred. 相似文献
11.
Rita M. De Miccolis Angelini Wassim Habib Caterina Rotolo Stefania Pollastro Francesco Faretra 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(2):185-199
Resistance to the fungicide boscalid in laboratory mutants of Botryotinia fuckeliana (Botrytis cinerea) was investigated. The baseline sensitivity to boscalid was evaluated in terms of colony growth (EC50 = 0.3–3 μg ml−1; MIC = 10–30 μg ml−1) and conidial germination (EC50 = 0.03–0.1 μg ml−1; MIC = 1–3 μg ml−1) tests. Mutants were selected in vitro from wild-type strains of the fungus on a fungicide-amended medium containing acetate as a carbon source. Mutants showed
two different levels of resistance to boscalid, distinguishable through the conidial germination tests: low (EC50 ∼ 0.3 μg ml−1, ranging from 0.03 to 1 μg ml−1; MIC > 100 μg ml−1) and high (EC50 > 100 μg ml−1) resistance. Analysis of meiotic progeny from crosses between resistant mutants and sensitive reference strains showed that
resistant phenotypes were due to mutations in single major gene(s) inherited in a Mendelian fashion, and linked with both
the Daf1 and Mbc1 genes, responsible for resistance to dicarboximide and benzimidazole fungicides, respectively. Gene sequence analysis of
the four sub-units of the boscalid-target protein, the succinate dehydrogenase enzyme, revealed that single or double point
mutations in the highly conserved regions of the iron-sulphur protein (Ip) gene were associated with resistance. Mutations
resulted in proline to leucine or phenylalanine replacements at position 225 (P225L or P225F) in high resistant mutants, and
in a histidine to tyrosine replacement at position 272 (H272Y) in low resistant mutants. Sequences of the flavoprotein and
the two transmembrane sub-units of succinate dehydrogenase were never affected. 相似文献
12.
Yu Chen Yong Zhang Jian Yao Yun-Fei Li Xue Yang Wen-Xiang Wang Ai-Fang Zhang Tong-Chun Gao 《Phytoparasitica》2013,41(3):277-284
False smut, caused by Ustilaginoidea virens, is an important emerging disease of rice (Oryza sativa L.) in China. Up to now, as most varieties with high yielding and good quality are susceptible or even highly susceptible to false smut in most rice-growing ecological regions, especially in Anhui Province, chemical control with fungicides would be an important measure for the control of this disease. The ergosterol biosynthesis inhibitor (EBI) fungicides, such as prochloraz, difenoconazole, propiconazole and tebuconazole, are extensively used in China for the control of rice diseases, such as rice sheath blight and rice blast. In this study, a total of 102 U. virens isolates (from Anhui Province of China) were tested for their sensitivity to these four EBI fungicides during the stage of mycelial growth. The EC50 ranges of values for prochloraz, difenoconazole, propiconazole and tebuconazole inhibiting mycelial growth of the 102 U. virens isolates were 0.04–0.75, 0.04–1.08, 0.04–0.38 and 0.03–0.57 μg?ml?1, with the average EC50 values of 0.32?±?0.08, 0.45?±?0.08, 0.19?±?0.03 and 0.21?±?0.06 μg?ml?1, respectively. These values suggested that the tested U. virens isolates were very sensitive to these four EBI fungicides. Results of field trials showed that two sprays of three of the fungicides exhibited greater control efficacy than a single spray for the control of rice false smut. Two sprays of each was better than a single spray for the control of rice sheath blight. Two sprays of 50% propiconazole EC at 300 g a.i. ha?1 gave the best control of rice false smut at both two sites during the two consecutive years, 2010 and 2011, with the control efficacy ranging from 71.5 to 74.3%. Sensitivity of the field U. virens isolates to EBI fungicides should be monitored. Mixtures, as well as alternation with other fungicides with different modes of action, should be tested. 相似文献
13.
The effects of some fungicides used against citrus diseases, on mycelial growth and conidial germination of Isaria farinosa (Holmsk.) Fries [Sordariomycetes: Hypocreales] and also on the pathogenicity of the fungus on citrus mealybug, Planococcus citri (Risso), were determined. Systemic fungicides such as tebuconazole, penconazole and nuarimol were the most effective as regards
both conidial germination and mycelial growth. Protective fungicides such as captan, chlorothalonil, mancozeb and propineb
inhibited conidial germination at between 1 and 5 μg ml−1 concentration, but captan, chlorothalonil and propineb did not inhibit the mycelial growth at 5,000 μg ml−1. Mancozeb inhibited mycelial growth between 2,500 and 5,000 μg ml−1. Sulphur and copper oxychloride did not inhibit the fungus even at very high concentrations. Sulphur, copper oxychloride,
fosetyl-al, chlorothalonil and carbendazim did not decrease the mortality percentage caused by I. farinosa. Tebuconazole, penconazole and mancozeb were the most effective and respectively reduced the mortality from 83% to 33%, 28%
and 30% in the ovisacs, from 81% to 29%, 27% and 29% in the 1st instar larvae, and from 84% to 34% in the adult females. 相似文献
14.
W. V. Pereira R. G. F. Morales A. I. G. Bauer K. Kudlawiec L. L. May-De-Mio 《Plant pathology》2020,69(1):68-76
Demethylation inhibitor (DMI) fungicides are used to control brown rot in stone fruit worldwide. However, their specific mode of action can select resistant isolates of Monilinia fructicola. Monilinia fructicola resistant to DMI fungicides are associated with a fitness cost in the absence of selective pressure, indicating that the sensitive population can be re-established when discontinuing the fungicide in the field. This work aimed to build up the sensitive population of M. fructicola after discontinuing the use of tebuconazole for successive crop seasons. The sensitivity of M. fructicola to tebuconazole was assessed in four commercial peach orchards in Paraná and São Paulo States from 2012/13 to 2015/16. Different fungicide programmes were used and DMI fungicides were discontinued from 2013/14. The sensitivity of M. fructicola to tebuconazole was assessed by a mycelial growth assay in vitro and by determining the frequency of the G461S mutation in the MfCYP51 gene. The isolates from Paraná had high sensitivity to the fungicide across all seasons and the frequency of the G461S mutation remained below 5%. The isolates from São Paulo were highly resistant in the 2012/13 season; however, there was a gradual decline until 2015/16. In addition, the G461S mutation frequency in Sao Paulo State was about 80% in the 2012/13 season, but reduced until it was completely undetectable in 2015/16. These results provide evidence that resistance can be managed in orchards with high selective pressure to tebuconazole after discontinuing the use of the fungicide for at least 3 years. 相似文献
15.
Alba Valéria da Silva Pereira Ricardo Brainer Martins Sami Jorge Michereff Marcelo Bezerra da Silva Marcos Paz Saraiva Camara 《European journal of plant pathology / European Foundation for Plant Pathology》2012,132(4):489-498
Stem rot caused by Lasiodiplodia theobromae is an important postharvest disease of papaya in Brazil, responsible for reducing the quality and quantity of fruits. Fungicide
use is one of the main disease management measures. However, there are no estimates available of pathogen sensitivity to commonly
employed fungicides. Therefore, the EC50 from 120 isolates of L. theobromae from northeastern Brazil, representative of six populations of the pathogen, was estimated in vitro for fungicides of the
methyl benzimidazole carbamates—MBC (benomyl and thiabendazole) and demethylation-inhibiting—DMI (imazalil, prochloraz, tebuconazole)
groups. Mycelial growth on fungicide-free media and virulence on papaya fruits of the MBC-sensitive and non-sensitive isolates
were compared. For MBCs, 8.4% of isolates were non-sensitive to fungicides. For the remaining 91.6%, the mean EC50 ranged from 0.002 to 0.13 μg ml−1 and 0.36 to 1.27 μg ml−1 for benomyl and thiabendazole, respectively. For DMIs, the mean EC50 range for imazalil was 0.001 to 2.27 μg ml−1, 0.04 to 1.75 μg ml−1 for prochloraz, and 0.14 to 4.05 μg ml−1 for tebuconazole. The EC50 values of non-sensitive isolates were significantly (P≤0.05) higher those for the sensitive isolates for each of the DMI fungicides. Differences (P≤0.05) were found in the levels of sensitivity to DMI fungicides among the isolate populations associated with orchards. The
populations from two orchards were less sensitive to DMIs. No solid evidence was found for fitness costs relating to MBC non-sensitive
isolates because mycelial growth in fungicide-free media and virulence on papaya fruits were similar to those of sensitive
isolates. 相似文献
16.
Dionicio Fuentes-Aragón Vladimiro Guarnaccia Angel Rebollar-Alviter Sandra B. Juárez-Vázquez Fortino Aguirre-Rayo Hilda V. Silva-Rojas 《Plant pathology》2020,69(6):1125-1138
Colletotrichum spp. are known causal agents of anthracnose in a broad host range, causing severe losses. Currently, the most effective way to reduce disease is by fungicide application, which could give rise to resistant populations. This study aimed to determine the Colletotrichum species present in conventional and organic mango orchards and to evaluate their pathogenicity and sensitivity to the benzimidazole fungicide thiophanate-methyl. Seventy-one isolates from fruit with symptoms and symptomless leaves were obtained. From these, 20 representative morphotypes were analysed based on glyceraldehyde-3-phosphate dehydrogenase partial gene sequencing. A subset of 10 isolates based on different species, isolation source, and fungicide sensitivity was used for morphological and multilocus phylogenetic analysis. Colletotrichum queenslandicum was only identified in conventional production systems, C. chrysophilum only in organic systems, and C. asianum and C. siamense in both. Pathogenicity tests showed all species were pathogenic, and only C. asianum caused symptoms via both unwounded and wounded inoculation methods. Overall, 25.3% of isolates (n = 18) that belong to C. siamense, isolated from a conventional orchard, grew on thiophanate-methyl amended media at 1,000 µg/ml, suggesting high resistance. Resistance was not correlated with any common point mutations at positions 198 and 200 of the β-tubulin 2 protein, as commonly found in other fungal pathogens resistant to benzimidazole. The 74.7% remaining isolates (n = 53) belonging to the other species were sensitive, reaching 100% inhibition at <10 µg/ml. Even with benzimidazole application, anthracnose symptoms persist due to the emergence of pathogenic Colletotrichum subpopulations that are resistant to thiophanate-methyl. 相似文献
17.
Effect of hot water treatment on peach volatile emission and Monilinia fructicola development 下载免费PDF全文
A. Spadoni L. Cappellin F. Neri A. Algarra Alarcon A. Romano M. Guidarelli F. Gasperi F. Biasioli M. Mari 《Plant pathology》2015,64(5):1120-1129
The effect of hot water treatment (HWT) to control peach brown rot was investigated. Peaches were dipped in water at 60°C for 60 s and artificially inoculated with Monilinia fructicola conidia. HWT failed to control brown rot if applied before inoculation and microscopic observations revealed a stimulatory effect on germ tube elongation of M. fructicola conidia placed immediately after HWT on the fruit surface, compared to the control. The influence of fruit volatile emission due to HWT was performed on the pathogen conidia exposed to the headspace surrounding peaches. The results showed an increase of M. fructicola conidial germination ranging from 33 to 64% for cultivars Lucie Tardibelle and Red Haven heat‐treated peaches, respectively, compared to the control. The volatile blend emitted from heat‐treated fruit was analysed by solid‐phase microextraction/gas chromatography‐mass spectrometry (SPME/GC‐MS) and proton transfer reaction‐time of flight‐mass spectrometry (PTR‐ToF‐MS). Fifty compounds were detected by SPME/GC‐MS in volatile blends of cv. Lucie Tardibelle peaches and significant differences in volatile emission were observed among heated and control fruit. Using PTR‐ToF‐MS analysis, acetaldehyde and ethanol were detected at levels 15‐ and 28‐fold higher in heated fruit compared to unheated ones, respectively. In vitro assays confirmed the stimulatory effect (60 and 15%) of acetaldehyde (0·6 μL L?1) and ethanol (0·2 μL L?1) on M. fructicola conidial germination and mycelial growth, respectively. The results showed that volatile organic compounds (VOCs) emitted from heat‐treated peaches could stimulate M. fructicola conidial germination, increasing brown rot incidence in treated peaches when the inoculation occurs immediately after HWT. 相似文献
18.
Detection and quantification of Fusarium commune in host tissue and infested soil using real‐time PCR 下载免费PDF全文
Z. X. Zhu L. Zheng T. Hsiang G. L. Yang D. L. Zhao B. Lv Y. F. Chen J. B. Huang 《Plant pathology》2016,65(2):218-226
Fusarium wilt caused by Fusarium commune is a major limiting factor for Chinese water chestnut (Eleocharis dulcis) production in China. A SYBR Green I real‐time quantitative polymerase chain reaction (qPCR) assay was developed based on the mitochondrial small subunit rDNA of F. commune. Assay specificity of the FO1/FO2 primer set was tested on 41 fungal isolates, and only a single PCR band of c. 178 bp from F. commune was amplified. The detection limits of the assay were 1 fg μL?1 pure F. commune genomic DNA, 1 pg μL?1 F. commune genomic DNA mixed with host plant genomic DNA (0·5 ng μL?1), and 1000 conidia/g soil (artificially inoculated). The amount of F. commune DNA in stem tissues detected by qPCR was significantly correlated with the disease severity (DS) ratings; however, the qPCR assay showed no significant positive correlation between spore densities in soil of different fusarium wilt DS groupings and the DS ratings. The qPCR assay was further applied to 76 soil samples collected from commercial fields of E. dulcis during the 2011 and 2012 growing seasons. The spore density of F. commune detected was positively correlated with disease index in the 2012 growing season but not in 2011. The qPCR method can be used for rapid and specific detection of F. commune in plant and soil samples, which will facilitate monitoring of the pathogen and improvement of disease management. 相似文献
19.
Hui Feng Jiajia Chen Ze Yu Ke Li Zhe Li Yaxin Li Zhe Sun Yuanchao Wang Wenwu Ye Xiaobo Zheng 《Plant pathology》2020,69(6):1083-1092
Pythium and Phytopythium spp. cause seed decay, damping off, and root rot in soybean, wheat, and many other crops. However, their diversity and importance as pathogens, particularly in different crop rotation systems, are largely unknown. A survey was conducted in the Huang-Huai region, one of the main areas of soybean–wheat rotation farming in China. In 2016–2018, we collected 300 soybean seedlings and 150 field soil samples from several representative locations, and identified 26 Pythium and 6 Phytopythium spp. from 212 isolates, based on internal transcribed spacer 2 (ITS2) and cytochrome oxidase subunit 1 sequences. The pathogenicity of these isolates was evaluated by growing soybean and wheat seeds in dishes and pots containing oomycete cultures. We found that 12 Pythium spp. (but no Phytopythium spp.) showed high pathogenicity on soybean and/or wheat, and nine of them (75%) were highly pathogenic on both crops. Among the nine species, Pythium spinosum, Pythium ultimum, Pythium species 1 (tentatively designated as ‘Candidatus Pythium huanghuaiense’), Pythium aphanidermatum, and Pythium myriotylum were highly abundant among all isolates (15%, 10%, 9%, 8%, and 5%, respectively). Nine species were selected for testing of sensitivity to the fungicides metalaxyl and mefenoxam. The EC50 values were all less than 10 μg/ml, indicating little resistance. Minimum inhibitory concentration values indicated isolates were about twice as sensitive to mefenoxam as to metalaxyl. These results provide a systematic understanding of Pythium and Phytopythium species associated with soybean in the Huang-Huai region, which is important for disease management and breeding programmes. 相似文献
20.
桃褐腐病菌(Monilinia fructicola)对3种杀菌剂的敏感性 总被引:1,自引:0,他引:1
采用生长速率法测定了采自北京平谷区3个桃园的125株桃褐腐病菌对甲基硫菌灵、戊唑醇和异菌脲3种杀菌剂的敏感性,发现甲基硫菌灵对桃褐腐病菌的EC50主要分布在1.0×10-5~0.2μg/mL,戊唑醇对桃褐腐病菌的EC50主要分布在0.006~0.022μg/mL之间。异菌脲对桃褐腐病菌的EC50主要分布在0.15~0.55μg/mL之间。研究结果表明,北京地区的桃褐腐病菌对这3种杀菌剂都比较敏感,未产生明显的抗药群体。建立了褐腐病菌对异菌脲抗药性的敏感基线。而且,数据分析表明:甲基硫菌灵、戊唑醇和异菌脲之间均不存在交互抗性。 相似文献