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1.
Plant Dis ; 103(10): 2505-2511, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31408403

RESUMO

Botrytis fruit rot (BFR) is a major disease that affects strawberry production in Florida and worldwide. BFR management relies on frequent fungicide applications. A meta-analysis was conducted on the outcomes from nine field trials to evaluate the efficacy and profitability of conventional and biological fungicides compared with a nontreated control (NTC). All trials were conducted in Florida between the 2005/06 and 2016/17 growing seasons. Fungicide treatments were applied weekly, and plots were harvested twice a week for yield and BFR incidence quantification. Treatments were grouped into four categories: NTC, multisite only (Thiram), Standard (captan alternated with fludioxonil + cyprodinil), and Bacillus. Following primary analyses, a random effects network meta-analytical model was fitted to estimate the mean yield and BFR incidence responses for each treatment group and to compare means between pairs of groups. The Thiram and the Standard treatment groups increased yield by 378.8 and 502.2 kg/ha/week, respectively, compared with the NTC. The yield difference between Bacillus and NTC was not statistically significant. Besides increasing yield, Thiram and Standard also reduced BFR incidence by approximately 10% compared with the NTC. The mean yield responses and among-study variability from the meta-analysis were used to estimate the probability of a given yield response in a new future trial. The Standard and Thiram treatment groups showed higher estimated probabilities of increasing yield and resulting in a profitable return on application investments than the Bacillus group of treatments. The results from this study provide growers with information that will aid their decision-making process regarding BFR management.


Assuntos
Bacillus , Botrytis , Fragaria , Fungicidas Industriais , Controle Biológico de Vetores , Bacillus/fisiologia , Botrytis/fisiologia , Florida , Fragaria/microbiologia , Frutas/microbiologia , Fungicidas Industriais/economia , Fungicidas Industriais/normas , Controle Biológico de Vetores/economia , Controle Biológico de Vetores/normas
2.
Plant Dis ; 103(10): 2541-2547, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31432772

RESUMO

To prevent the spread of anthracnose in strawberry plants and characterize the metabolic changes occurring during plant-pathogen interactions, we developed a method for the early diagnosis of disease based on an analysis of the metabolome by gas chromatography-mass spectrometry. An examination of the metabolic profile revealed 189 and 202 total ion chromatogram peaks for the control and inoculated plants, respectively. A partial least squares discriminant analysis (PLS-DA) model was conducted for the reliable and accurate discrimination between healthy and diseased strawberry plants, even in the absence of disease symptoms (e.g., early stages of infection). ANOVA (analysis of variance) and orthogonal partial least squares analysis (OPLS) identified 20 metabolites as tentative biomarkers of Colletotrichum theobromicola infection (e.g., citric acid, d-xylose, erythrose, galactose, gallic acid, malic acid, methyl α-galactopyranoside, phosphate, and shikimic acid). At least some of these potential biomarkers may be applicable for the early diagnosis of anthracnose in strawberry plants. Moreover, these metabolites may be useful for characterizing pathogen infections and plant defense responses. This study confirms the utility of metabolomics research for developing diagnostic tools and clarifying the mechanism underlying plant-pathogen interactions. Furthermore, the data presented herein may be relevant for developing new methods for preventing anthracnose in strawberry seedlings cultivated under field conditions.


Assuntos
Biomarcadores , Colletotrichum , Fragaria , Cromatografia Gasosa-Espectrometria de Massas , Metabolômica , Biomarcadores/análise , Colletotrichum/fisiologia , Fragaria/microbiologia
3.
J Agric Food Chem ; 67(33): 9265-9276, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31361479

RESUMO

Fungal infections significantly alter the emissions of volatile organic compounds (VOCs) by plants, but the mechanisms for VOCs affecting fungal infections of plants remain largely unknown. Here, we found that infection by Botrytis cinerea upregulated linalool production by strawberries and fumigation with linalool was able to inhibit the infection of fruits by the fungus. Linalool treatment downregulated the expression of rate-limiting enzymes in the ergosterol biosynthesis pathway, and this reduced the ergosterol content in the fungi cell membrane and impaired membrane integrity. Linalool treatment also caused damage to mitochondrial membranes by collapsing mitochondrial membrane potential and also downregulated genes involved in adenosine triphosphate (ATP) production, resulting in a significant decrease in the ATP content. Linalool treatment increased the levels of reactive oxygen species (ROS), in response to which the treated fungal cells produced more of the ROS scavenger pyruvate. RNA-Seq and proteomic analysis data showed that linalool treatment slowed the rates of transcription and translation.


Assuntos
Botrytis/efeitos dos fármacos , Fragaria/metabolismo , Frutas/microbiologia , Monoterpenos/metabolismo , Doenças das Plantas/microbiologia , Compostos Orgânicos Voláteis/metabolismo , Trifosfato de Adenosina/metabolismo , Botrytis/crescimento & desenvolvimento , Fragaria/química , Fragaria/microbiologia , Frutas/química , Frutas/metabolismo , Interações Hospedeiro-Patógeno , Membranas Mitocondriais/efeitos dos fármacos , Membranas Mitocondriais/metabolismo , Monoterpenos/farmacologia , Doenças das Plantas/prevenção & controle , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteômica , Espécies Reativas de Oxigênio/metabolismo , Compostos Orgânicos Voláteis/farmacologia
4.
Plant Dis ; 103(9): 2417-2424, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31322978

RESUMO

Macrophomina phaseolina, the causal agent of charcoal rot, affects strawberry crowns, inducing plant collapse. The fungus survives in the soil through the production of microsclerotia and is usually controlled by preplant fumigation of soil. However, in the 2016 to 2017 Florida strawberry season, even after soil fumigation, about 30% plant mortality still occurred in plastic-covered beds that were used for a second season and where crop residue (mainly old strawberry crowns) was disposed of between beds. Therefore, this study was conducted to determine if M. phaseolina can survive on strawberry debris over summer in Florida and if so, verify whether strawberry debris might act as a source of inoculum for new transplants. Crowns from the previous season were collected from commercial farms where charcoal rot had been reported, and M. phaseolina was recovered from all samples. In a research field, infected crowns were buried in the soil at different depths and retrieved every 2 weeks during the summer. After 8 weeks, M. phaseolina could be recovered at all depths. Moreover, inoculation of strawberry plants by drenching the soil, dipping roots, or spraying leaves with a M. phaseolina microsclerotial suspension from pure cultures or infected crowns produced symptoms with differences in incubation periods depending on cultivar susceptibility. Furthermore, infected crowns disposed of in the aisles between beds or buried next to new transplants of cultivars Strawberry Festival, Florida Beauty, and Winterstar induced charcoal rot, with the level of aggressiveness depending on the cultivar susceptibility and inoculum placement in the field.


Assuntos
Ascomicetos , Fragaria , Doenças das Plantas , Ascomicetos/fisiologia , Florida , Fragaria/microbiologia , Doenças das Plantas/microbiologia , Raízes de Plantas/microbiologia
5.
Microbiol Res ; 223-225: 120-128, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31178044

RESUMO

Plant growth-promoting bacteria have been highlighted by their potential for application in plant production, allowing the reduction of the use of fertilizers and pesticides, which is due to the ability to stimulate the growth of plants by nitrogen-fixation and production of phytohormones, such as indole-3-acetic acid (IAA). The objective of this study was to verify the potential of plant growth promotion of 25 wild isolates from the Agricultural Microbiology Culture Collection of the Federal University of Lavras (CCMA-UFLA) through the evaluation of the biological nitrogen-fixation capacity and the production of IAA. In addition, the growth of three selected strains inoculated on roots of strawberry seedlings in greenhouse conditions was evaluated. The experiment was conducted in a completely randomized design (CRD), with an 8 × 2 factorial schemes involving eight combinations of bacteria: alone, in pairs and threes, plus the control without inoculation. Two fertilizer levels were used (0% and 50% of nitrogen), totaling 16 treatments with eight replicates each. After 75 days, variables such as root length, root dry weight, aerial part length, aerial part dry weight, leaf number, total dry mass and ultrastructural analysis of the inoculated and uninoculated roots, were evaluated. The results showed that the strawberry crop responded positively to inoculation with the three bacteria combined Azospirillum brasilense (Ab-V5) + Burkholderia cepacia (CCMA 0056) + Enterobacter cloacae (CCMA 1285) compared to the uninoculated controls. More expressive responses in terms of plant growth were observed in relation to the combined inoculation of the three bacterial strains plus fertilizer application with 50% of nitrogen.


Assuntos
Fenômenos Fisiológicos Bacterianos , Fragaria/crescimento & desenvolvimento , Fragaria/microbiologia , Fixação de Nitrogênio , Desenvolvimento Vegetal , Azospirillum brasilense/fisiologia , Bactérias/classificação , Bactérias/crescimento & desenvolvimento , Bactérias/isolamento & purificação , Bactérias/metabolismo , Biomassa , Burkholderia cepacia/fisiologia , Enterobacter cloacae , Ácidos Indolacéticos/metabolismo , Nitrogênio , Reguladores de Crescimento de Planta/metabolismo , Folhas de Planta/microbiologia , Raízes de Plantas/microbiologia , Plântula
6.
Plant Dis ; 103(8): 1974-1982, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31210598

RESUMO

Fusarium solani is an emerging pathogen reported on Spanish strawberry crops both in nurseries and in fruit production fields, causing wilt and root rot. Pathogenicity, morphocultural characteristics, and sensitivity to biocides of 103 F. solani isolates recovered from symptomatic strawberry plants and soils from both Spanish strawberry areas were determined. The differences of isolates within and between nurseries and field crops in relation to these parameters were analyzed. Considerable variability in morphological and pathogenic characteristics was observed among the isolates in both areas. The majority of isolates were not pathogenic (62%), and only 38 F. solani isolates (37.62%) caused disease on strawberry plants under controlled conditions; 52.63% of pathogenic isolates induced low severity symptoms. Almost 70% of pathogenic isolates caused stunting on plants. The morphological characters that best explain the F. solani variability (86.85%) were colony color and the presence of macroconidia on culture medium. The sensitivity to the fumigants tested was similar between the isolates from nurseries and fruit production fields, showing greater sensitivity to the field doses of dazomet and chloropicrin. However, the isolates were less sensitive to metam sodium and poorly sensitive to 1,3-dichloropropene. This work can contribute to the advancement of sustainable production of strawberry.


Assuntos
Fragaria , Fusarium , Desinfetantes/farmacologia , Fragaria/microbiologia , Fusarium/efeitos dos fármacos , Fusarium/fisiologia , Doenças das Plantas/microbiologia , Microbiologia do Solo
7.
J Sci Food Agric ; 99(12): 5341-5349, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31058322

RESUMO

BACKGROUND: The strawberry (Fragaria × ananassa Duch.) is, among small fruits, the most cultivated and commercialized in Portugal. Recent studies have evidenced the positive effect of plant growth-promoting bacteria (PGPB) inoculation on strawberry production and, at the same time, provided an alternative strategy to reduce the use of fertilizers. In this study the effects of root inoculation with three PGPB strains (Pedobacter sp. CC1, Bacillus safensis B106 and Bacillus subtilis B167A) on the physiology, growth, fruit production and quality of strawberry cv. Camarosa are presented. RESULTS: PGPB inoculation significantly accelerated crop maturation, with inoculated plants fruiting about 2 weeks earlier than non-inoculated plants. Inoculated plants with Pedobacter sp. CC1 and Bacillus safensis B106 influenced the gas exchange parameters of strawberry plants. The contents of total phenolics and flavonoids in strawberry leaves were found to be greater with Pedobacter sp. CC1, when compared with non-inoculated plants. Furthermore, plants inoculated with the same bacterial strain showed enhancement in the dimensions of fruits, especially fruit length, and shape as well as in the total soluble solids content (°Brix). CONCLUSIONS: The results showed that the PGPB Pedobacter sp. CC1 improved performance of strawberry plants, suggesting that it could be a potential biofertilizer for strawberry plant nutrition. © 2019 Society of Chemical Industry.


Assuntos
Inoculantes Agrícolas/crescimento & desenvolvimento , Bacillus/fisiologia , Fragaria/crescimento & desenvolvimento , Fragaria/microbiologia , Frutas/química , Pedobacter/fisiologia , Fertilizantes/análise , Flavonoides/análise , Flavonoides/metabolismo , Fragaria/química , Fragaria/metabolismo , Frutas/crescimento & desenvolvimento , Frutas/metabolismo , Fenóis/análise , Fenóis/metabolismo , Portugal
8.
Mar Drugs ; 17(5)2019 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-31137530

RESUMO

Water extracts and polysaccharides from Anabaena sp., Ecklonia sp., and Jania sp. were tested for their activity against the fungal plant pathogen Botrytis cinerea. Water extracts at 2.5, 5.0, and 10.0 mg/mL inhibited B. cinerea growth in vitro. Antifungal activity of polysaccharides obtained by N-cetylpyridinium bromide precipitation in water extracts was evaluated in vitro and in vitro at 0.5, 2.0, and 3.5 mg/mL. These concentrations were tested against fungal colony growth, spore germination, colony forming units (CFUs), CFU growth, and on strawberry fruits against B. cinerea infection with pre- and post-harvest application. In in vitro experiments, polysaccharides from Anabaena sp. and from Ecklonia sp. inhibited B. cinerea colony growth, CFUs, and CFU growth, while those extracted from Jania sp. reduced only the pathogen spore germination. In in vitro experiments, all concentrations of polysaccharides from Anabaena sp., Ecklonia sp., and Jania sp. reduced both the strawberry fruits infected area and the pathogen sporulation in the pre-harvest treatment, suggesting that they might be good candidates as preventive products in crop protection.


Assuntos
Anabaena/química , Antifúngicos/farmacologia , Botrytis/efeitos dos fármacos , Fragaria/efeitos dos fármacos , Fragaria/microbiologia , Feófitas/química , Rodófitas/química , Antifúngicos/isolamento & purificação , Botrytis/fisiologia , Polissacarídeos/isolamento & purificação , Polissacarídeos/farmacologia , Esporos Fúngicos/efeitos dos fármacos , Água/química
9.
Plant Dis ; 103(6): 1249-1251, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30932736

RESUMO

Fusarium wilt of strawberry, caused by the soilborne pathogen Fusarium oxysporum f. sp. fragariae, is a growing threat to the strawberry industry worldwide. Symptoms of the disease typically include stunting, wilting, crown discoloration, and eventual plant death. When Fusarium wilt was discovered in California, the disease was not known to occur anywhere else in North America. Long distance movement of the pathogen would most likely occur through transport of infected plants, which seems plausible if strawberry plants can sustain infections without showing symptoms of disease. The results of this study document that F. oxysporum f. sp. fragariae can move through stolons of infected mother plants and colonize first-generation daughter plants. The pathogen can also move through stolons from first to second-generation daughter plants. Daughter plants of both generations were always symptomless. The pathogen was recovered from both roots and petioles of infected daughter plants. Similar results were obtained for two cultivars known to be susceptible to Fusarium wilt, Albion and Monterey. Transmission through stolons from mother to daughter plants also occurred in the resistant cultivar, San Andreas, but less frequently than in Albion and Monterey.


Assuntos
Fragaria , Fusarium , California , Fragaria/microbiologia , Fusarium/fisiologia , Doenças das Plantas/microbiologia , Raízes de Plantas/microbiologia , Caules de Planta/microbiologia
10.
Plant Dis ; 103(6): 1256-1263, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30964420

RESUMO

Xanthomonas fragariae, the causal agent of angular leaf spot (ALS) of strawberry, is a quarantine pathogen in some export markets, causing trade restrictions and economic loss to the California fresh-market strawberry industry. Preharvest chemical management options are limited to copper, and there are no postharvest treatments available that reduce populations of the pathogen if ALS is detected at an export destination. Here, we report high preharvest efficacy for the experimental bactericide amino thiadiazole and the commercial product zinc thiadiazole, alone and in mixtures with low rates of copper or the antibiotic kasugamycin, with average disease incidence reduction of up to 92.8% compared with the control. Although effective against quarantine insect pests of strawberry, postharvest methyl bromide fumigation was ineffective against X. fragariae in diseased plant tissue at a standard commercial rate. Postharvest propylene oxide fumigation, used for decades by the California nut industries for insect and microbial disinfestation, significantly reduced X. fragariae populations in infected leaflet tissues by at least 2.5-log compared with controls at a dose of ≥142 µg/ml for 2 h at 15 to 20°C. Fumigated leaflets showed little to no phytotoxicity at effective rates, and fumigated fruit were not significantly affected in appearance or susceptibility to postharvest gray mold or Rhizopus rot following storage at 2°C for 3 days and at 15°C for an additional 5 days. Together, these new treatments offer potential strategies for establishing a systems approach with preharvest treatments significantly reducing the risk of ALS on plants and, in response to quarantine detections, a postharvest fumigation treatment that reduces viable pathogen populations in existing lesions.


Assuntos
Agricultura/métodos , Fragaria , Xanthomonas , Animais , Antibacterianos/farmacologia , California , Comércio , Fragaria/microbiologia , Frutas/microbiologia , Fumigação , Xanthomonas/efeitos dos fármacos , Xanthomonas/fisiologia
11.
Plant Dis ; 103(6): 1319-1325, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30998417

RESUMO

Anthracnose is one of the most common diseases in strawberry plants. Colletotrichum gloeosporioides is the major cause of anthracnose in China, including Zhejiang Province. Early, specific, reliable, and time-saving detection is urgently needed to prevent the further spread of C. gloeosporioides, guiding farmers to utilize chemicals to control anthracnose. In this study, we showed that the high resistance to pyraclostrobin, caused by a point mutation at codon 143 (GGT→GCT) in the cytochrome b gene of C. gloeosporioides was prevalent in the strawberry growing regions, and we developed a loop-mediated isothermal amplification (LAMP) assay as a detection method. Primer sets S0 and S4 could be used to specifically detect C. gloeosporioides isolates and the G143A mutations, respectively. A detection limit of 10-2 ng (10 pg), which is at least 10-fold more sensitive than conventional polymerase chain reaction, was achieved by the LAMP assay. Here, we utilized lateral-flow devices (LFDs), nitrocellulose membranes that can absorb nucleic acids, to acquire the total genomic DNA of strawberry plants within 2 min. The LFD membranes were used as DNA templates for the LAMP assays to accurately detect strawberry plants infected with C. gloeosporioides. This diagnostic method for strawberry anthracnose was accomplished within 1 h, including the sample preparation and LAMP assays. Collectively, we developed a sensitive and practical method for monitoring C. gloeosporioides and its quinone outside inhibitor-resistant mutants. The LAMP assay for detection of C. gloeosporioides in strawberry plants has great potential for rapid strawberry anthracnose surveillance and will provide farmers with advice on preventing C gloeosporioides at the early stages of strawberry development.


Assuntos
Agricultura , Colletotrichum , Farmacorresistência Fúngica , Fragaria , Técnicas de Amplificação de Ácido Nucleico , Agricultura/métodos , Antifúngicos/farmacologia , China , Colletotrichum/efeitos dos fármacos , Colletotrichum/genética , Farmacorresistência Fúngica/genética , Fragaria/microbiologia , Doenças das Plantas/microbiologia , Estrobilurinas/farmacologia
12.
Plant Dis ; 103(5): 1006-1013, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30946629

RESUMO

Isolates of the Fusarium oxysporum species complex have been characterized as plant pathogens that commonly cause vascular wilt, stunting, and yellowing of the leaves in a variety of hosts. F. oxysporum species complex isolates have been grouped into formae speciales based on their ability to cause disease on a specific host. F. oxysporum f. sp. fragariae is the causal agent of Fusarium wilt of strawberry and has become a threat to production as fumigation practices have changed in California. F. oxysporum f. sp. fragariae is polyphyletic and limited genetic markers are available for its detection. In this study, next-generation sequencing and comparative genomics were used to identify a unique genetic locus that can detect all of the somatic compatibility groups of F. oxysporum f. sp. fragariae identified in California. This locus was used to develop a TaqMan quantitative polymerase chain reaction assay and an isothermal recombinase polymerase amplification (RPA) assay that have very high sensitivity and specificity for more than 180 different isolates of the pathogen tested. RPA assay results from multiple field samples were validated with pathogenicity tests of recovered isolates.


Assuntos
Fragaria , Fusarium , Filogenia , California , Fragaria/microbiologia , Fusarium/genética , Fusarium/fisiologia , Genes Fúngicos/genética , Doenças das Plantas/microbiologia
13.
BMC Plant Biol ; 19(1): 128, 2019 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-30953454

RESUMO

BACKGROUND: The soil-borne vascular pathogen Verticillium dahliae causes severe wilt symptoms in a wide range of plants including strawberry (Fragaria × ananassa). To enhance our understanding of the effects of V. dahliae on the growth and development of F. × ananassa, the expression patterns of 21 PR-10 genes were investigated by qPCR analysis and metabolite changes were determined by LC-MS in in vitro F. × ananassa plants upon pathogen infection. RESULTS: The expression patterns of the 21 isoforms showed a wide range of responses. Four PR-10 genes were highly induced in leaves upon pathogen infection while eight members were significantly up-regulated in roots. A simultaneously induced expression in leaves and roots was detected for five PR-10 genes. Interestingly, two isoforms were expressed upon infection in all three tissues (leaves, roots and stems) while no induction was detected for two other members. Accumulation of antifungal catechin and epicatechin was detected upon pathogen infection in roots and stems at late stages, while caffeic acid and citric acid were observed only in infected roots. Production of abscisic acid, salicylic acid, jasmonic acid (JA), gibberellic acid and indole acetic acid (IAA) was induced in infected leaves and stems at early stages. IAA and JA were the sole hormones to be ascertained in infected roots at late stages. CONCLUSIONS: The induction of several PR-10 genes upon infection of strawberry plants with V. dahliae suggest a role of PR-10 genes in the defense response against this pathogen. Production of phytohormones in the early stages of infection and antifungal metabolites in late stages suppose that they are implicated in this response. The results may possibly improve the control measures of the pathogen.


Assuntos
Fragaria/genética , Interações Hospedeiro-Patógeno , Doenças das Plantas/imunologia , Reguladores de Crescimento de Planta/metabolismo , Proteínas de Plantas/metabolismo , Verticillium/fisiologia , Ácido Abscísico/metabolismo , Ciclopentanos/metabolismo , Fragaria/imunologia , Fragaria/metabolismo , Fragaria/microbiologia , Oxilipinas/metabolismo , Doenças das Plantas/microbiologia , Folhas de Planta/genética , Folhas de Planta/imunologia , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Ácido Salicílico/metabolismo
14.
Phytopathology ; 109(7): 1293-1301, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30852972

RESUMO

Strawberry anthracnose fruit rot and root necrosis, caused by Colletotrichum acutatum, are primary limiting factors in fruit production fields in the United States. Recent research focusing on the phenotypic and genetic characteristics of this species has shed light on the diversity of the C. acutatum species complex. In this study, we performed multilocus sequence analysis of four genetic loci to characterize 217 C. acutatum isolates collected over a 23-year period from symptomatic plant tissues of strawberry from six different states. The results revealed two Colletotrichum spp. (C. nymphaeae and C. fioriniae), with 97.7% of the isolate collection (212 of 217) belonging to C. nymphaeae as a dominant clonal linage, regardless of the isolation source. No correlation between species groups and geographical origins of the isolates was observed. Further sequence comparison between historical and contemporary isolates showed the same populations being widely distributed throughout the strawberry nurseries and production fields in the United States and Canada. Subsequently, a subset of 12 isolates representing different quinone-outside inhibitor fungicide resistance profiles from root or fruit tissue of strawberry was selected for comparison of pathogenicity on strawberry. In this test, isolates of different resistance groups or different isolation sources exhibited a similar degree of aggressiveness and caused indistinguishable symptoms on strawberry crowns (P = 0.9555 and 0.7873, respectively) and fruit (P = 0.1638 and 0.1141, respectively), although a significant difference among individual isolates was observed in detached-fruit assays (P = 0.0123). Separate pathogenicity tests using isolates of the two species revealed C. nymphaeae being more aggressive than C. fioriniae in infecting strawberry roots and crowns (P = 0.0073). Therefore, given the occurrence and pathogenicity of C. nymphaeae, this species is likely the sole cause responsible for strawberry anthracnose in the United States.


Assuntos
Colletotrichum , Fragaria , Doenças das Plantas/microbiologia , Canadá , Fragaria/microbiologia , Frutas , Estados Unidos
15.
J Agric Food Chem ; 67(14): 4043-4053, 2019 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-30883111

RESUMO

Cold plasma technology offers new opportunities to the decontamination and preservation of fruits and vegetables. In the present research, strawberries were cut into four wedges and then treated with dielectric barrier discharge plasma at 45 kV for 1 min and stored for 1 week (4 °C). Metabolomic analysis suggested that plasma treatment improved the biosynthesis of the metabolites in the "flavones and flavonol biosynthesis" pathway and "biosynthesis of phenylpropanoids" pathway in fresh-cut strawberries. Physiological assay demonstrated that plasma treatment maintained the texture properties and inhibited microbial growth of fresh-cut strawberries. In addition, plasma treatment also promoted the accumulation of total phenolics, total flavonoid, and anthocyanin by enhancing the critical enzyme activities and activating related gene expression in phenylpropanoid as well as reactive oxygen species metabolism, which contributed greatly to the enhancement of antioxidant capacity of strawberry wedges. Our investigation provided a new perspective of the effect of plasma treatment on the safety and quality of strawberry wedges and suggested that cold plasma treatment holds promise as an emerging processing technology for improving the quality and antioxidant activity of postharvest fruits and vegetables.


Assuntos
Conservação de Alimentos/métodos , Fragaria/química , Frutas/efeitos dos fármacos , Gases em Plasma/farmacologia , Antioxidantes/metabolismo , Bactérias Aeróbias/genética , Bactérias Aeróbias/crescimento & desenvolvimento , Bactérias Aeróbias/isolamento & purificação , Fragaria/efeitos dos fármacos , Fragaria/metabolismo , Fragaria/microbiologia , Frutas/química , Frutas/metabolismo , Frutas/microbiologia , Metabolômica , Espécies Reativas de Oxigênio/metabolismo
16.
Plant Dis ; 103(4): 697-704, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30742553

RESUMO

Previous work has shown that raising the pH of acidic soil to near neutrality can reduce the incidence of Fusarium wilt. The basis for this effect has not been established. The present study assessed effects of pH on spore germination, growth, and infection of strawberry roots by Fusarium oxysporum f. sp. fragariae, the cause of Fusarium wilt of strawberry. There was not a significant effect of pH (5 versus 7) on the rate of spore germination at either 20 or 25°C for any of the three tested isolates (one representative of each clonal lineage of F. oxysporum f. sp. fragariae found in California). Likewise, pH did not have a significant effect on fungal growth at 20°C. At 25°C, two isolates grew faster at pH 7 than at pH 5. Growth of the third isolate was unaffected by the difference in pH. For the strawberry cultivar Albion, the frequency of root infection was significantly higher for plants grown in acidified soil (near pH 5) than for plants grown in soil near neutrality. The higher frequency of root infection in acidified soil was associated with a lower level of microbial activity, as measured by hydrolysis of fluorescein diacetate.


Assuntos
Fragaria , Fusarium , Esporos , California , Fragaria/microbiologia , Fusarium/fisiologia , Concentração de Íons de Hidrogênio , Doenças das Plantas/microbiologia , Esporos/crescimento & desenvolvimento
17.
Plant Dis ; 103(4): 729-736, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30777800

RESUMO

Botrytis fruit rot (BFR), caused by the necrotrophic fungus Botrytis cinerea, is the most important disease of strawberry and is mainly controlled by applications of fungicides from multiple chemical groups. To develop more effective and sustainable BFR management programs, field trials were conducted to evaluate the efficacy of fluopyram and penthiopyrad, two newly registered succinate dehydrogenase inhibitors (SDHIs), rotated or tank mixed with the multisites thiram and captan or the single-sites fludioxonil and fenhexamid. The treatments were applied at two different strawberry fields during the 2013-14 and 2014-15 seasons. Overall, tank mixtures of fluopyram and penthiopyrad increased yield and reduced BFR better than rotations with the same fungicides. The multisite thiram tank mixed with fluopyram reduced BFR incidence by 63 to 86% versus 56 to 84% when the two fungicides were rotated. Thiram tank mixed with penthiopyrad reduced BFR incidence by 55 to 72% versus 42 to 66% when rotated. Captan rotated or tank mixed with fluopyram had a positive effect on yield and BFR incidence, whereas the combination of captan with penthiopyrad had negative impacts. Similarly, the single-site fenhexamid had significant positive impacts when rotated or tank mixed with fluopyram but resulted in poor BFR control when combined with penthiopyrad. The rotation of fludioxonil with both SDHIs had a significant positive effect, although its combination with fluopyram was more effective. The multirotation consisting of both SDHIs and different multi- and single-site fungicides did not provide a greater efficacy than the dual rotation or tank-mixture programs. Our findings suggest more scrutiny is needed when recommending tank-mixture or rotation partners for new fungicides to ensure compatibility and enhanced BFR management. Future recommendations should emphasize the importance of such selections at an early stage for delaying fungicide resistance development and extending the lifespan of at-risk fungicides.


Assuntos
Botrytis , Microbiologia de Alimentos , Fragaria , Benzamidas/farmacologia , Botrytis/efeitos dos fármacos , Botrytis/enzimologia , Botrytis/fisiologia , Microbiologia de Alimentos/métodos , Fragaria/microbiologia , Frutas/microbiologia , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle , Pirazóis/farmacologia , Piridinas/farmacologia , Succinato Desidrogenase/antagonistas & inibidores , Tiofenos/farmacologia
18.
J Sci Food Agric ; 99(9): 4235-4241, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30801703

RESUMO

BACKGROUND: The antimicrobial activity of allyl-isothiocyanate (AITC) on plant pathogens is well known and has already been demonstrated in the strawberry with respect to Botritis cinerea fungal infection using postharvest biofumigation. In the present study, vapours of 0.08 mg L-1 of Brassica meal-derived AITC were applied to strawberry to assess its effect on fruit nutraceutical and biochemical parameters after 2 days of storage at 20 °C and 90% relative humidity. RESULTS: Allyl-isothiocyanate showed no detrimental effect on final strawberry quality, anti-oxidant properties or ascorbic acid content. By contrast, an increased amount of asparagine and a higher ascorbate and glutathione redox potential were registered in the fruit soon after treatment. A reversible glutathione depletion action of AITC was also observed. Finally, total AITC residues in treated strawberry were quantified and a relatively high amount of AITC-adducts was found in fruit tissues. CONCLUSION: The findings of the present study not only confirm the high potentiality of biofumigation with respect to extending the shelf-life of fruit, but also provide some insight regarding the mechanisms of action of AITC at the cellular level as a possible elicitor of fruit protective responses. Nevertheless, the nature of the AITC-adducts formed in fruit tissues needs further attention to enable a health and safety assessment of the final fruit. © 2019 Society of Chemical Industry.


Assuntos
Brassica/química , Suplementos Nutricionais/análise , Conservação de Alimentos/métodos , Conservantes de Alimentos/farmacologia , Fragaria/química , Frutas/química , Isotiocianatos/farmacologia , Extratos Vegetais/farmacologia , Botrytis/efeitos dos fármacos , Botrytis/fisiologia , Armazenamento de Alimentos , Fragaria/microbiologia , Frutas/microbiologia , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle
19.
Appl Microbiol Biotechnol ; 103(4): 1589-1597, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30610288

RESUMO

Grey mould, the most important disease of strawberry worldwide, is caused by Botrytis cinerea and a few additional Botrytis spp. Fungicide resistance is a growing problem and has become a limiting factor in strawberry production. In northern Germany, an annual survey of Botrytis isolates from commercial strawberry fields in 2010 to 2017 has revealed high (> 20%) frequencies of resistance to quinone-outside inhibitors, fenhexamid, boscalid, fludioxonil and cyprodinil, as well as lower (< 10%) shares of resistance to the recently released fluopyram. Iprodione and benzimidazoles have not been used in northern Germany for several years or decades, respectively, yet resistance to them was still detected. These observations are largely representative of the situation in many other strawberry-producing regions worldwide. The spread of strains with multiple resistance to several or even all currently used single-site fungicides is of particular concern and is probably promoted by their excessive use. Contaminated nursery material is a newly detected potential vehicle for the spread of strains with (multiple) fungicide resistance. Several complementary non-chemical measures are available to secure strawberry production in the face of weakening fungicide efficacies, and these are briefly discussed.


Assuntos
Botrytis/efeitos dos fármacos , Botrytis/crescimento & desenvolvimento , Farmacorresistência Fúngica , Fragaria/microbiologia , Fungicidas Industriais/farmacologia , Doenças das Plantas/microbiologia , Agricultura/métodos , Alemanha
20.
Int J Food Microbiol ; 292: 150-158, 2019 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-30599455

RESUMO

Strawberry has a limiting postharvest shelf life, especially because of soft rot. The antifungal activity of the essential oils (EOs) of Eucalyptus staigeriana, Lippia sidoides and Pimenta pseudocaryophyllus was tested in vitro against plant pathogen Rhizopus stolonifer. The chemical composition of the EO with the highest activity and its effects on pathogen morphology were verified. The in vivo antifungal activity of this EO associated with carboxymethylcellulose (CMC) coating, in preventive and curative applications, was also evaluated. L. sidoides EO presented the highest in vitro antifungal activity. The analysis of the chemical composition of this EO showed a prevalence of the compound thymol and the scanning and transmission electron microscopy showed that L. sidoides EO was able to cause damage to the cell wall and the intracellular components of the pathogen. Strawberries treated with L. sidoides EO associated with CMC presented a reduction in disease severity, especially when treated in a curative way.


Assuntos
Carboximetilcelulose Sódica/farmacologia , Fragaria/microbiologia , Fungicidas Industriais/farmacologia , Óleos Voláteis/farmacologia , Rhizopus/efeitos dos fármacos , Eucalyptus/química , Contaminação de Alimentos/prevenção & controle , Microbiologia de Alimentos , Lippia/química , Pimenta/química , Timol/farmacologia , Compostos Orgânicos Voláteis/farmacologia
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