scholarly journals First Report of Phytophthora infestans Genotype US23 Causing Late Blight in Canada

Plant Disease ◽  
2011 ◽  
Vol 95 (7) ◽  
pp. 873-873 ◽  
Author(s):  
L. M. Kawchuk ◽  
R. J. Howard ◽  
R. D. Peters ◽  
K. I. Al-Mughrabi
Keyword(s):  
United States ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
The United States ◽  
Western Canada ◽  
Eastern Canada ◽  
Disease Symptoms ◽  
Metalaxyl Sensitivity ◽  
Epidemiological Characteristics

Late blight is caused by the oomycete Phytophthora infestans (Mont.) de Bary and is one of the most devastating diseases of potato and tomato. Late blight occurs in all major potato- and tomato-growing regions of Canada. Its incidence in North America increased during 2009 and 2010 (2). Foliar disease symptoms appeared earlier than usual (June rather than July) and coincided with the identification of several new P. infestans genotypes in the United States, each with unique characteristics. Prior to 2007, isolates collected from potato and tomato crops were mainly US8 or US11 genotypes (1). However, P. infestans populations in the United States have recently experienced a major genetic evolution, producing isolates with unique genotypes and epidemiological characteristics in Florida and throughout the northeastern states (2). Recent discoveries of tomato transplants with late blight for sale at Canadian retail outlets prompted an examination of the genotypes inadvertently being distributed and causing disease in commercial production areas in Canada. Analysis of isolates of P. infestans from across Canada in 2010 identified the US23 genotype for the first time from each of the four western provinces (Manitoba, Saskatchewan, Alberta, and British Columbia) but not from eastern Canada. Allozyme banding patterns at the glucose phosphate isomerase (Gpi) locus indicated a 100/100 profile consistent with US6 and US23 genotypes (4). Mating type assays confirmed the isolates to be A1 and in vivo metalaxyl sensitivity was observed. Restriction fragment length polymorphic analysis of 50 isolates from western Canada with the multilocus RG57 sequence and EcoRI produced the DNA pattern 1, 2, 5, 6, 10, 13, 14, 17, 20, 21, 24, 24a, 25 that was indicative of US23 (3). The recently described P. infestans genotype US23 appears to be more aggressive on tomato, and although isolates were recovered from both tomato and potato, disease symptoms were often more severe on tomato. Results indicate that movement and evolution of new P. infestans genotypes have contributed to the increased incidence of late blight and that movement of the pathogen on retail plantlets nationally and internationally may provide an additional early season source of inoculum. A major concern is that the introduced new A1 populations in western Canada have established a dichotomy with the endogenous A2 populations in eastern Canada, increasing the potential for sexual recombination producing oospores and additional genotypes should these populations merge. References: (1) Q. Chen et al. Am. J. Potato Res. 80:9, 2003. (2) K. Deahl. (Abstr.) Phytopathology 100(suppl.):S161, 2010. (3) S. B. Goodwin et al. Curr. Genet. 22:107, 1992. (4) S. B. Goodwin et al. Phytopathology 88:939, 2004.

scholarly journals First Report of Late Blight Caused by Phytophthora infestans Clonal Lineage US-23 on Tomato and Potato in Wisconsin, United States

Plant Disease ◽  
2013 ◽  
Vol 97 (6) ◽  
pp. 839-839 ◽  
Author(s):  
A. J. Gevens ◽  
A. C. Seidl
Keyword(s):  
United States ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Weather Conditions ◽  
The United States ◽  
Clonal Lineage ◽  
Banding Patterns ◽  
First Report ◽  
Low Incidence ◽  
Epidemiological Characteristics

Tomato (Solanum lycopersicum) and potato (S. tuberosum) crops are grown on over 67,000 acres (27,114 ha) in Wisconsin annually. Late blight, caused by Phytophthora infestans (Mont.) deBary, is a potentially devastating disease that affects tomato and potato crops in Wisconsin every few years when inoculum is introduced and weather conditions favor disease. Incidence and severity of late blight are highly variable in these few years due to differences in pathogen clonal lineages, their timing and means of introduction, and weather conditions. Prevention of this disease through preventative application of fungicides can cost producers millions of dollars per year in additional chemical, fuel, and labor expenses. In 2009, late blight caused by P. infestans clonal lineage US-23 was observed on potato very late in the season in Vernon County, southwestern Wisconsin, in very low incidence and severity. In 2010, US-23 again appeared but on tomato in two southeastern Wisconsin counties, Waukesha and Ozaukee, again in low incidence and severity. Clonal lineages of P. infestans documented in Wisconsin in previous epidemics included US-8 in the mid-1990s and US-1 in the 1970s. Populations of P. infestans in the United States have recently undergone significant genetic change, resulting in isolates with unique clonal lineages and epidemiological characteristics (1). Foliar symptoms included water-soaked to dark brown circular lesions with pale green haloes accompanied by white pathogen sporulation. On tomato fruit, lesions were firm, sunken, and brown. Isolates of P. infestans were generated from field-infected tomato and potato foliar and fruit tissues collected by the authors and professional crop consultants. In initial pathogen confirmation analysis in 2009, three isolates of P. infestans were generated from one potato plant exhibiting multiple lesions from one of eight fields tested by placing infected leaf excisions onto Rye A agar amended with rifampicin and ampicillin. Axenic, single zoospore-derived cultures of isolates were generated from parent cultures and maintained on Rye A agar for further characterization. In 2010, three US-23 isolates were recovered from three locations (two counties), out of 20 fields tested. Mycelium was coenocytic with hyphal diameter of 5 to 8 μm (n = 50). Sporangia were limoniform or ovoid, semi to fully papillate, caducous, had short pedicels, and were 26.16 μm high × 18.17 μm wide (n = 50). The average length/width ratio was 1.42. Allozyme banding patterns at the glucose-6-phosphate isomerase (Gpi) locus indicated a 100/100 profile, consistent with the US-23 clonal lineage (3) Mating type assays confirmed the isolates to be A1 and in vitro intermediate mefenoxam sensitivity was observed (4). Genomic DNA was extracted with a phenol/chloroform/isoamyl alcohol solution and RFLP analysis was performed using the RG-57 probe on a representative isolate and resulted in banding patterns consistent with US-23 (2,3). The P. infestans clonal lineage US-23 was present in epidemics in 2009 and 2010 in the United States. Disease symptoms associated with US-23 were observed exclusively on potato in 2009 and on tomato in 2010 in Wisconsin. To our knowledge, this is the first report of P. infestans clonal lineage US-23 causing late blight on tomato and potato in Wisconsin and represents a change in the composition of the pathogen population from previous epidemic years. References: (1) K. Deahl. (Abstr.) Phytopathology 100:S161, 2010. (2) S. B. Goodwin et al. Curr. Genet. 22:107, 1992. (3) Hu et al. Plant Dis. 96:1323, 2012. (4) A. C. Seidl and A. J. Gevens. (Abstr.) Phytopathology 101(suppl.):S162, 2011.

scholarly journals First Report of Late Blight Caused by Phytophthora infestans Clonal Lineage US-23 on Tomato and Potato in Atlantic Canada

Plant Disease ◽  
2014 ◽  
Vol 98 (3) ◽  
pp. 426-426 ◽  
Author(s):  
C. P. Wijekoon ◽  
R. D. Peters ◽  
K. I. Al-Mughrabi ◽  
L. M. Kawchuk
Keyword(s):  
United States ◽  
Late Blight ◽  
New Brunswick ◽  
Phytophthora Infestans ◽  
Mating Type ◽  
Prince Edward Island ◽  
The United States ◽  
Clonal Lineage ◽  
Eastern Canada ◽  
The Us

Phytophthora infestans (Mont.) de Bary has produced significant losses in potato and tomato yield and quality during recent late blight epidemics in North America. During the 1990s, more aggressive and genetically diverse P. infestans genotypes migrated to Canada and the United States (2). For example, US-8 became predominant and was found to be more aggressive in potato than previous clonal lineages of P. infestans. Recent P. infestans genotypes in potato and tomato plants from the United States and Canada include US-22, US-23, and US-24 representing clonal lineages with unique epidemiological characteristics (2,3,4). Characteristic phenotypic traits have been described for P. infestans clonal lineages US-8, US-22, US-23, and US-24 based on the mating type, mefenoxam sensitivity, pathogenicity, and rate of germination suggesting an association between phenotypic variations and the genotype (1,4). Analysis of P. infestans isolates collected in Canada during 2010 revealed the presence of the US-23 clonal lineage in four different areas of western Canada but not in eastern Canada (4). Isolates of P. infestans collected from eastern Canada for several years prior to 2011 were all US-8 A2 mating type. Isolation and analysis of 98 P. infestans isolates in 2011 from New Brunswick and Prince Edward Island followed standard procedures (2,3,4). Results confirmed the presence of the US-23 clonal lineage in Atlantic Canada on potato and tomato leaves with late blight symptoms, increasing the genetic complexity of P. infestans in eastern Canada. Allozyme banding patterns at the glucose-6-phosphate isomerase (Gpi) locus showed a 100/100 profile in 10 P. infestans isolates, consistent with the US-23 clonal lineage (2,3,4). Furthermore, in vitro mefenoxam sensitivity was observed in all 10 P. infestans US-23 isolates from New Brunswick and Prince Edward Island. Mating type assays confirmed the isolates were of the A1 mating type. RFLP analysis of EcoR1-digested genomic DNA using the multilocus RG57 sequence as a probe produced the DNA pattern 1, 2, 5, 6, 10, 13, 14, 17, 20, 21, 24, 24a, 25, indicative of US-23 (2,4). Microsatellite analysis using polymorphic markers on New Brunswick and Prince Edward Island P. infestans isolates produced the Pi4B 213/217 bp, D13 134 bp, and PiG11 140/155 bp profile of P. infestans US-23 (1). These results show the presence of the P. infestans A1 and A2 mating types in New Brunswick and Prince Edward Island, which increases the probability of sexual recombination. To our knowledge, this is the first report of P. infestans clonal lineage US-23 causing late blight in New Brunswick and Prince Edward Island, increasing the genetic diversity from previous years in eastern Canada and underscoring the annual fluctuation occurring in the population composition. References: (1) G. Danies et al. Plant Dis. 97:873, 2013. (2) S. B. Goodwin et al. Phytopathology 84:553, 1994. (3) C. H. Hu et al. Plant Dis. 96:1323, 2012. (4) M. L. Kalischuk et al. Plant Dis. 96:1729, 2012.

scholarly journals Phenotypic Characterization of Recent Clonal Lineages of Phytophthora infestans in the United States

Plant Disease ◽  
2013 ◽  
Vol 97 (7) ◽  
pp. 873-881 ◽  
Author(s):  
G. Danies ◽  
I. M. Small ◽  
K. Myers ◽  
R. Childers ◽  
W. E. Fry
Keyword(s):  
United States ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
The United States ◽  
Phenotypic Characterization ◽  
Phenotypic Traits ◽  
Mating Types ◽  
Late Blight Disease ◽  
Blight Disease

Phytophthora infestans, the causal agent of late blight disease, has been reported in the United States and Canada since the mid-nineteenth century. Due to the lack of or very limited sexual reproduction, the populations of P. infestans in the United States are primarily reproducing asexually and, thus, show a simple genetic structure. The emergence of new clonal lineages of P. infestans (US-22, US-23, and US-24) responsible for the late blight epidemics in the northeastern region of the United States in the summers of 2009 and 2010 stimulated an investigation into phenotypic traits associated with these genotypes. Mating type, differences in sensitivity to mefenoxam, differences in pathogenicity on potato and tomato, and differences in rate of germination were studied for clonal lineages US-8, US-22, US-23, and US-24. Both A1 and A2 mating types were detected. Lineages US-22, US-23, and US-24 were generally sensitive to mefenoxam while US-8 was resistant. US-8 and US-24 were primarily pathogenic on potato while US-22 and US-23 were pathogenic on both potato and tomato. Indirect germination was favored at lower temperatures (5 and 10°C) whereas direct germination, though uncommon, was favored at higher temperatures (20 and 25°C). Sporangia of US-24 released zoospores more rapidly than did sporangia of US-22 and US-23. The association of characteristic phenotypic traits with genotype enables the prediction of phenotypic traits from rapid genotypic analyses for improved disease management.

scholarly journals First Report of Late Blight Caused by Phytophthora infestans Clonal Lineage US-23 on Potato in Idaho

Plant Disease ◽  
2015 ◽  
Vol 99 (3) ◽  
pp. 417-417 ◽  
Author(s):  
P. S. Wharton ◽  
P. Nolte ◽  
W. W. Kirk ◽  
S. Dangi ◽  
A. J. Gevens
Keyword(s):  
United States ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Agar Medium ◽  
The United States ◽  
Eastern United States ◽  
Clonal Lineage ◽  
Predominant Genotype ◽  
The Us ◽  
Pure Cultures

Late blight, caused by Phytophthora infestans (Mont.) de Bary, is a destructive disease of potato (Solanum tuberosum) and tomato (S. lycopersicum) in the United States. Prior to 2007, the US-8 clonal lineage was the predominant genotype in the United States (4). Since 2007, a significant genetic change in the population of P. infestans occurred in the eastern United States with the appearance of new isolates with unique genotypes and epidemiological characteristics (3). These new genotypes US-22, US-23, and US-24 are sensitive to metalaxyl and represent mating types A2, A1, and A1, respectively (1,2). Prior to 2012, only US-8 had been documented in Idaho (5). In 2013, late blight was discovered in late August on potato crops (cv. Russet Norkotah) in Bingham and Madison counties, ID. Infected foliage (four samples from Bingham County and five from Madison) was sent to Michigan State University and the University of Wisconsin for confirmation of P. infestans and characterization of the isolates. Five sections from the leading edge of lesions were excised with a sterilized scalpel and placed on potato tuber slices (‘Dark Red Norkotah’). Pathogen sporulation on the excised lesions was enhanced by incubation in plastic boxes lined with moistened paper towels for 5 days at 18°C in the dark. The sporulating lesions were transferred onto pea agar medium (160 g peas, 5 g sucrose, 15 g agar, 700 ml distilled water) amended with 50 mg/ml vancomycin. Ten pure cultures were obtained for each of 4 isolates per county by hyphal tipping. Cellulose acetate electrophoresis was conducted to determine Gpi allozyme genotype of the 4 isolates (4). The allozyme banding patterns were 100/100 at the Gpi locus, consistent with previously reported analyses of the US-23 genotype (1,2). Genomic DNA was extracted from 10 pure cultures using the DNeasy Plant Mini Kit (Qiagen, Germantown, MD), and SSR analyses were performed. Microsatellite markers Pi02, Pi4B, Pi63, PiG11, and D13 were used in SSR analyses. Pi02, Pi4B, and Pi63 had alleles of 162/164, 213/217, and 270/279 bp in size, respectively which is consistent with the reference US-23 genotype (1). However, heterozygosity was detected at locus D13 in the Idaho genotype with allele size of 134/210 bp and an additional allele of 140/155/176 bp at locus PiG11. This is different from the standard US-23 genotype (homozygous alleles 134/134 at locus D13 and two alleles 140/155 at locus PiG11). These allele changes indicate the isolates may be variants of US-23 isolates as all other phenotypic characteristics were similar to those of reference US-23 isolates. The Idaho genotypes were sensitive to metalaxyl both in vitro on rye A agar medium amended with metalaxyl at <0.1 ppm, and in vivo on Ridomil treated foliage tests at <0.1 ppm (1,2). Mating type assays confirmed the pathogen to be the A1 mating type. In the 2009 and 2010 late blight epidemics in the eastern United States, US-23 was the predominant genotype, but to our knowledge this genotype has never been reported previously in Idaho. Thus, this is the first known report of P. infestans genotype US-23 causing late blight on potato in Idaho, indicating a change in the population of P. infestans. In Idaho, the source of this genotype remains unknown, although infected tomatoes have been implicated in the widespread dissemination of this genotype of P. infestans in the eastern United States. References: (1) G. Danies et al. Plant Dis. 97:873, 2013. (2) C. Hu et al. Plant Dis. 96:1323, 2012. (3) K. Deahl. (Abstr.) Phytopathology 100:S161, 2010. (4) S. B. Goodwin et al. Plant Dis. 79:1181, 1995. (5) USAblight. Recent US Genotypes. Online: www.usablight.org/node/52 , retrieved 3 January 2014.

scholarly journals Natural Occurrence of Phytophthora infestans Causing Late Blight on Woody Nightshade (Solanum dulcamara) in New York

Plant Disease ◽  
2010 ◽  
Vol 94 (8) ◽  
pp. 1063-1063 ◽  
Author(s):  
K. L. Deahl ◽  
F. Perez ◽  
C. J. Baker ◽  
R. W. Jones ◽  
L. Cooke ◽  
...  
Keyword(s):  
United States ◽  
New York ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Mating Type ◽  
The United States ◽  
Plant Diseases ◽  
Home Garden ◽  
Mitochondrial Haplotype ◽  
Solanum Dulcamara

Woody nightshade (Solanum dulcamara) is a common hedgerow herbaceous perennial in the United States, one of only three native Solanum spp. S. dulcamara is a known host of Phytophthora infestans (3), but infection is rarely reported. There is a U.S. record from Maryland (2); in 1947, Peterson (4) stated that this species had never been found blighted in its natural habitat, although in 1960 it was listed as a host of P. infestans in New York (1). The A2 mating type has not been reported on this host. On 2 July, 2009, leaf lesions similar to those of P. infestans on potato were found on wild S. dulcamara at Riverhead, NY. The plant was growing in a home garden within 10 m of potato and tomato plants infected with P. infestans. When two infected leaves of S. dulcamara were incubated for 24 h under high humidity, a pathogen growth developed around the lesion margins that was characterized by hyaline mycelium bearing lemon-shaped sporangia that released motile zoospores after chilling in water, which is consistent with P. infestans. The caducous and limoniform to ovoid sporangia were 39 to 50 μm (average 45 μm) × 26 to 28 μm (average 27 μm) with a length/breadth ratio of 1.66. No oospores were observed. Three isolates were obtained from this plant during July 2009. Growth on rye agar was indistinguishable from that of local tomato isolates of P. infestans. Detached leaflets of S. dulcamara and S. tuberosum, inoculated with the woody nightshade isolates and kept in a humid chamber, became infected and developed profuse sporulation within 5 days. The pathogen isolated was confirmed as P. infestans by morphological, biochemical, and molecular characteristics. Inoculations of attached leaves of potted S. dulcamara plants resulted in necrotic lesions with many sporangia; sporulation also developed on inoculated, attached, and detached tomato leaves. P. infestans was reisolated and identity confirmed as before. The three isolates were A2 mating type, metalaxyl-resistant, mitochondrial haplotype Ia. All were glucose-6-phosphate isomerase 100/122 and peptidase 100/100, as confirmed with single-spore isolates. RG57 fingerprint analysis confirmed that isolates from woody nightshade, tomato, and potato obtained from the same and nearby sites were identical. Although P. infestans in the United States belongs to the new population, which may infect a wider host range than the old US-1 clonal lineage, S. dulcamara infections have only been found when late blight is already widespread in neighboring fields and there is no evidence to suggest that woody nightshade acts as an overwintering host in the United States. References: (1) Anonymous. Index of Plant Diseases in the United States. Page 456 in: Agric. Handb. No. 165, 1960 (2) C. Cox. Phytopathology 38:575, 1948. (3) D. C. Erwin and O. K. Ribeiro. Page 190 in: Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (4) L. C. Peterson. Am. Potato J. 24:188, 1947.

scholarly journals La contrebande des produits du tabac au Canada entre 1985 et 1994 et le cas particulier du Québec

Criminologie ◽  
2005 ◽  
Vol 30 (1) ◽  
pp. 53-72 ◽  
Author(s):  
Marc Alain
Keyword(s):  
United States ◽  
Driving Force ◽  
The United States ◽  
Eastern Canada ◽  
Mass Consumption ◽  
Cigarette Taxes ◽  
Geographical Factors ◽  
The World ◽  
The Difference

The professional smuggling of mass consumption products develops when demand for a product is not adequately fulfilled by the legitimate market. The difficulties encountered in supplying are, in most contemporary cases, caused by real rarity of the desired product. For other cases, however, the rarity is largely virtual in that government taxes aimed at the product in question lead to increasing the product's price to a prohibitive end. This was the case with cigarettes in Canada between 1985 and 1994. Before both, the federal and provincial, governments decided to drastically decrease cigarette taxes in February 1994, the price for a pack of cigarettes was five to six times higher than the same product in the United States. This article begins with a brief review of the contribution made by economists in regard to contemporary smuggling. Focus will be aimed at common characteristics of the smuggling phenomenon across the world. Elements which are more particular to the Canadian smuggling situation will be identified as well. While the difference in the price of cigarettes between Canada and the United States would seem to be the undeniable driving force behind the development of smuggling activities at the countries ' border, one key question remains unexplained. Why was the volume of contraband unequally distributed across Canada even though the price of cigarettes remained largely consistent throughout all provinces? The level of organization of smuggling networks was much higher in Eastern Canada, and particularly in Quebec, than it was in the western provinces. It is argued that the reasons for this are not only due to price, but to a series of political, historical, and geographical factors which allowed cigarette smugglers to function better in Quebec than in the rest of the country.

scholarly journals The 2009 Late Blight Pandemic in the Eastern United States – Causes and Results

Plant Disease ◽  
2013 ◽  
Vol 97 (3) ◽  
pp. 296-306 ◽  
Author(s):  
W. E. Fry ◽  
M. T. McGrath ◽  
A. Seaman ◽  
T. A. Zitter ◽  
A. McLeod ◽  
...  
Keyword(s):  
United States ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Current Situation ◽  
Causal Agent ◽  
Community Supported Agriculture ◽  
Eastern United States ◽  
Tomato Crop ◽  
History Of ◽  
Mainstream Press

The tomato late blight pandemic of 2009 made late blight into a household term in much of the eastern United States. Many home gardeners and many organic producers lost most if not all of their tomato crop, and their experiences were reported in the mainstream press. Some CSAs (Community Supported Agriculture) could not provide tomatoes to their members. In response, many questions emerged: How did it happen? What was unusual about this event compared to previous late blight epidemics? What is the current situation in 2012 and what can be done? It's easiest to answer these questions, and to understand the recent epidemics of late blight, if one knows a bit of the history of the disease and the biology of the causal agent, Phytophthora infestans.

scholarly journals Respuesta de biosurfactantes producidos por Pseudomonas fluorescens para el control de la gota de la papa Phytophthora infestans (Mont) de Bary, bajo condiciones controlada.

2010 ◽  
Vol 11 (1) ◽  
pp. 21
Author(s):  
Hugo F. Rivera ◽  
Erika P. Martínez ◽  
Jairo A. Osorio ◽  
Edgar Martínez
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Pseudomonas Fluorescens ◽  
Negative Impact ◽  
Potato Late Blight ◽  
Pathogen Resistance ◽  
Production Costs ◽  
In Vitro Assays

<p>Phytophthora infestans (Mont.) de Bary, agente causal de la gota de la papa, es considerado la principal limitante de la producción de este cultivo en Colombia. El control habitual del patógeno se realiza con fungicidas de tipo sistémico, que incrementan los costos de producción, pueden inducir la resistencia del patógeno y tiene un impacto negativo en el ambiente. Por tanto, se llevó a cabo este estudio con el propósito de buscar alternativas amigables con el ambiente, que hagan parte de un paquete tecnológico eficaz de control. Dos cepas nativas de Psedomonas fluorescens (039T y 021V), provenientes de cultivos de papa, fueron evaluadas contra P. infestans. Las suspensiones bacterianas y los biosurfactantes parcialmente purificados (BPP), producidos por éstas (obtenidos en medio mínimo de sales con querosén), fueron aplicados sobre foliolos desprendidos en ensayos in vitro y experimentos in vivo en plantas de papa, en condiciones controladas en casa de malla. Los resultados demostraron la capacidad que tienen los biosurfactantes y las suspensiones bacterianas para controlar al patógeno, ya que el BPP 039T logró reducir el nivel de severidad de la enfermedad en 79,9% in vitro y 38,5% in vivo, mientras que el BPP 021V redujo en 78,7% in vitro y 30,2% in vivo. Las suspensiones bacterianas redujeron el nivel de severidad en 72,4% (039T) y 66,1% (021V) en las evaluaciones in vitro y 35% en los experimentos in vivo. Los resultados de esta investigación muestran el potencial que tienen los biosurfactantes para el control de la gota en Colombia.</p><p> </p><p><strong>Evaluation of Biosurfactants Produced by Pseudomonas fluorescens for Potato Late Blight Control (Phytophthora infestans (Mont) de Bary) Under Controlled Conditions</strong></p><p>Phytophthora infestans (Mont.) de Bary, causal agent of potato late blight is considered the main limiting pathogen for the production of this crop in Colombia. The usual control of the disease has been performed with systemic fungicides which increase production costs, can induce pathogen resistance and have a negative impact on the environment. Therefore, this study was carried out in order to find effective and environmentally friendly control alternatives for potato late blight. Two Pseudomonas fluorescens native strains (039T and 021V) isolated from potato crops were evaluated against P. infestans. Bacterial suspensions (obtained from minimal salts medium added with kerosene) and partially purified biosurfactants (BPP) were applied on detached leaflets for in vitro assays and on potato plants in greenhouse, for in vivo assays and the measure of inhibitory effect of the disease was assessed. The results showed the ability of P. fluorescens biosurfactants and bacterial suspensions to control the pathogen. BPP 039T was able to reduce the level of severity disease by 79.9% in vitro and 38.5% in vivo, whereas BPP 021V decreased 78.7% in vitro and 30.2% in vivo. Bacterial suspensions reduced the severity level in 72.4% (039T) and 66.1% (021V) in vitro assessments and 35% in the in vivo experiment. These results show the potential of P. fluorescens biosurfactants to control the potato late blight in Colombia.</p>

Sign in / Sign up

Export Citation Format

Share Document