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Browsing by Author "Backman, Paul A."

Now showing 1 - 14 of 14
  • Assessment of application timing of Bacillus spp. to supress pre- and postharvest diseases of apple
    Poleatewich, A. M.; Ngugi, H. K.; Backman, Paul A. (The American Phytopathological Society, 2012)
    In response to consumer environmental and health concerns concerning chemical pesticides, more attention has been placed on the development of biological control agents for the mitigation of postharvest diseases. However, postharvest biocontrol products are not currently widely used due to variable efficacy. The purpose of this study is to determine the potential effectiveness of certain biological agents (Bacillus spp.) in the control of preharvest (foliar apple scab) and postharvest (bitter rot) diseases in apples. Golden Delicious and Rome Beauty cultivars were assessed weekly for apple scab in a preharvest test. Upon harvest, the apples were wounded and inoculated with bitter rot and monitored over eight days. Treatment groups included: preharvest application of Bacillus spp., no preharvest application, post-harvest application of Bacillus spp., and no postharvest application. Applications of Bacillus spp. In May or May and June reduced apple scab most effectively, while postharvest or postharvest plus preharvest application reduced the size of bitter rot lesions significantly. Additional research is needed to determine the most effective timing and rate of application.
  • Atahualpa’s Revenge: The Spread of Quinoa Downy Mildew
    Testen, Anna L.; Backman, Paul A. (Northeastern Division of the American Phytopathological Society, 2011)
    The Andean crop quinoa, Chenopodium quinoa, has gained popularity in recent years due to its nutritious seed and desirable agricultural traits, such as its tolerance to drought and high saline soils. Prized by the Inca, quinoa is now highly desirable to health conscious consumers in North America and Europe. Quinoa also has interesting applications to plant pathology, including being a “universal” virus host as well as its production of antimicrobial compounds. Quinoa is affected by quinoa downy mildew, caused by Peronospora variabilis (formerly P. farinosa f. sp. chenopodii) which attacks quinoa throughout its native range. Quinoa downy mildew is capable of severely reducing yield and is the most devastating disease of this crop. Quinoa downy mildew has been reported in Denmark, Canada and India, despite the diverse growing conditions found in these countries. Most recently, quinoa downy mildew was reported in the United States when it was discovered in two Pennsylvania quinoa trials in 2011. Disease was first limited to 5-10 plants in areas within the plantings, but the cool, rainy conditions present during the 2011 field season quickly led to an epidemic of quinoa downy mildew in Pennsylvania. Koch’s postulates were verified with the pathogen and its identity confirmed with molecular and morphological techniques. P. variabilis is seedborne, with oospores present under the pericarp, but it is also capable of infecting other Chenopodium species including Chenopodium album. However, downy mildew was not observed on any nearby Chenopodium species while conditions were conducive to the disease on quinoa.
  • Bacterial endophytes of perennial crops for management of plant disease
    Melnick, Rachel L.; Bailey, B. A.; Backman, Paul A. (Springer, 2013)
    Bacterial endophytes, microorganisms which inhabit the internal tissues of plants, can suppress disease and are often used as a biological control in annual crops. Less research, however, has been applied to the use of bacterial endophytes to prevent disease in perennial crops, which presents a more complex challenge. However, exploration of their potential as a biological control in perennial crops has been limited. This chapter assembles current knowledge on the subject, providing case studies on bacterial endophytes for cacao pod diseases and citrus tree diseases.
  • Bacterial endophytes: Bacillus spp. from annual crops as potential biological control agents of black pod rot of cacao
    Melnick, Rachel L.; Zidack, N. K.; Bailey, B. A.; Maximova, S. N.; Guiltinan, M.; Backman, Paul A. (Netherlands: Elsevier, 2008)
    This study examines methods to reduce black pod rot in cacao plants.
  • Detection and expression of enterotoxin genes in endophytic strains of Bacillus cereus
    Melnick, Rachel L.; Testen, Anna L.; Poleatewich, A. M.; Backman, Paul A.; Bailey, B. A. (Society for Applied Microbiology, 2012-03-06)
    The aim of this study was to determine whether endophytic Bacillus cereus isolates from agronomic crops possessed genes for the nonhaemolytic enterotoxin (Nhe) and haemolysin BL (HBL) and, therefore, have the potential to cause diarrheal illness in humans.
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    Detection and incidence of Pernospora variabilis in quinoa seeds
    Testen, A. M.; Backman, Paul A. (2012)
    This poster describes the research undertaken to determine the level of imported quinoa contamination with quinoa downy mildew, caused by Pernospora variabilis, as well as to develop a rapid method of detection by DNA primers. The majority of lots coming from a wide variety of sources were found to have been contaminated with the pathogen, indicating it is more widespread than anticipated. Additionally, DNA primers for P. variabilis were shown to be effective in identifying most cases of contamination. This poster won third prize at the 2012 Penn State University Graduate Research Exhibition.
  • Evaluación de bacterias endófitas para el control de enfermedades de importancia económica en papa
    Plata, G.; Backman, Paul A.; Poleatewich, A. M. (Cochabamba, Bolivia: Revista de Agricultura, 2011)
    Con el proposito de reducir el uso de plaguicidas al momento de la siembra para el control de rizoctoniasis, roña y costra plateada en el cultivo de papa (Solanum tuberosum), se establecio un ensayo en los invernaderos de la Fundacion PROINPA. Este ensayo se realizo con la variedad Waych'a utilizando tres bacterias endofitas en forma individual o combinada. Se trabajo con un sustrato de campo naturalmente infestado, el cual fue mezclado con tierra esterilizada en una relacion de 1:9. Los tubérculos fueron tratados antes de la siembra con las suspensiones de bacterias a una concentración de 1x10^(8) ucf/ml y un testigo quimico (Dividend cuyo ingrediente activo es el Difenoconazole). Ninguno de los tratamientos evaluados control la costar plateada. En el caso de roña, el único control eficiente, fue el tratamiento con el fungicida sintético Difenoconazole (nombre commercial: Dividentd) y para rizoctoniasis los mejores tratamientos fueron las bacterias endófitas GB 03 y GB 34. Probablemente, por alguna interacción entre ellos (competencia), la mezcia de ambas bacterias no m ostró la misma eficiencia que cuando se las evaluó independientemente.
  • Evaluación de bacterias endófitas para el control de enfermedades foliares en haba
    Plata, G.; Backman, Paul A.; Poleatewich, A. M. (Cochabamba, Bolivia: Revista de Agricultura, 2011)
    En la busqueda de alternativas amigables con el medio ambiente que controlen manchas foliares en el cultivo de haba, se realizó un ensayo en invernadero utilizando bacterias endófitas del género Bacillus sp.
  • First Report of Ascochyta Leaf Spot of Quinoa Caused by Ascochyta sp. in the United States
    Testen, Anna L.; McKemy, J. M.; Backman, Paul A. (2013)
    This report describes infection of Qunioa in Pennsylvania with the Ascochyta Leaf Spot.
  • First report of quinoa downy mildew caused by Peronospora variabilis in the United States
    Testen, Anna L.; McKemy, J. M.; Backman, Paul A. (The American Phytopathological Society, 2012)
    First report of finding quinoa downy mildew in the United States. The disease affects quinoa grown in Andean Region.
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    First report of quinoa downy mildew in the United States: Implications for global quinoa production
    Testen, A. M.; Backman, Paul A. (2011)
    This poster describes the first reported case of quinoa downy mildew in the United States and its implications for global production.
  • Isolation of endophytic endospore-forming bacteria from Theobroma cacao as potential biological control agents of cacao diseases
    Melnick, Rachel L.; Suárez, C.; Bailey, B. A.; Backman, Paul A. (Elsevier, Inc., 2011)
    This article describes research on the effectiveness of biological controls of cacao fungal diseases. The study was conducted using endophytes from Ecuador, and treatments were shown to be effective.
  • Molecular detection of Peronospora variabilis in quinoa seeds and phylogeny of the quinoa downy mildew pathogen in South America and the United States
    Testen, Anna L.; Jimenez-Gasco, M.; Ochoa, J. B.; Backman, Paul A. (2014)
    As Quinoa production increases in response to growing global demand for the crop, it is necessary to develop improved production practices that will support sustainable production. To that end, this paper examines the ability of the Bacillus species of bacteria to colonize quinoa and to promote quinoa growth, and seeks to identify source of inoculum for Peronospora variabilis, the cause of the quinoa downy mildow disease. Bacillus populations isolated from Pennsylvanian Chenopodium album, Ecuadorean C. quinoa, and Bolivian C. quinoa were screened for the ability to solubilize tricalcium phosphate and this phenotype was paired with 16S sequence data to determine if there were species based patterns of tricalcium phosphate solubilization. Seed-based detection methods using sequencing and PCR with specific primers were developed to detect seedborne oospores of P. variabilis. It was found that seedborne oospores likely play a significant role in the spread of quinoa downy mildew, making the development of management methods for these seedborne oospores critical. Combining these research themes, the potential for Bacillus to reduce the severity of quinoa downy mildew was tested.
  • Plant growth promoting characteristics of Bacillus species associated with Chenopodium quinoa
    Testen, Anna L.; Backman, Paul A. (2013)
    As demand for organic quinoa increases and production expands, organic methods, such as the use of plant growth promoting bacteria, are needed to sustain quinoa production. To better understand the potential of Bacillus species to promote growth and reduce disease in quinoa (Chenopodium quinoa), a survey of three Bacillus populations from Bolivian, Ecuadorean and domestic Chenopodium spp. was performed. Four Bacillus species groups common to all populations were tested, including the B. subtilis, B. megaterium, B. simplex, and B. cereus species groups. Nearly 500 isolates were assayed for tricalcium phosphate solubilization, phytase production, IAA production, chitinase production and fungal antagonism. Patterns of specific plant growth promoting phenotypes were observed in different Bacillus species groups across all populations. For example, the tricalcium phosphate phenotype was universal in the B. subtilis and B. megaterium species groups, whereas IAA production was only observed in the B. simplex and B. megaterium species groups. Chitinase production was observed in the B. cereus species group and rarely in other species groups, whereas phytase production was common to all species groups. Isolates with potential for improving quinoa sustainability were identified in this study and isolates with multiple characteristics or consortia of single character Bacilli will be examined in greenhouse and field studies.