Browsing by Author "Yoder, Keith S."

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    2016 Spray Bulletin for Commercial Tree Fruit Growers
    Pfeiffer, Douglas G.; Bergh, J. Christopher; Frank, Daniel L.; Hooks, C. R. R.; Walsh, C. S.; Yoder, Keith S.; Rahan, Mahfaz; Kotcon, J. B.; Derr, Jeffrey F.; Chandran, Rakesh S.; Weaver, Michael W.; Brown, Amy; Parkhurst, James A. (2016-01-01)
    This is a multi-state guide, with orchard recommendations for Virginia, West Virginia and Maryland.
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    2017 Spray Bulletin for Commercial Tree Fruit Growers. Va. Coop. Ext. Serv. Publ. 456-419
    Pfeiffer, Douglas G.; Bergh, J. Christopher; Wilson, James M.; Frank, Daniel L.; Hooks, C. R. R.; Sherif, Sherif M.; Walsh, C. S.; Yoder, Keith S.; Rahman, M.; Kotcon, J. B.; Derr, Jeffrey F.; Chandran, Rakesh S.; Weaver, Michael J.; Brown, Amy; Parkhurst, James A. (2016)
    Integrated pest management (IPM) is the approach emphasized in this guide; some aspects of IPM are incorporated throughout, although this guide mainly deals with the chemical component of IPM. IPM combines biological control from predators with selective chemical application for maintaining pest populations below economic threshold levels. This approach requires that growers give careful consideration to the selection, application rate and timing of chemical sprays. The degree of integration achieved will vary according to the management ability, training and objectives of the orchardist. Inadequate monitoring or implementation of IPM practices will lead to unsatisfactory results. In order to encourage the biological control components of the program, growers must consider the toxicity of chemicals to predators (Table 9, page 59) in addition to their efficacy against fruit pests (Tables 7 and 8, pages 56-58).
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    2020 Spray Bulletin for Commercial Tree Fruit Growers: Virginia, West Virginia, and University of Maryland
    Pfeiffer, Douglas G.; Bergh, J. Christopher; Wilson, James; Hooks, C. R. R.; Sherif, Sherif M.; Walsh, C. S.; Yoder, Keith S.; Rahman, Mahfaz; Kotcon, J. B.; Derr, Jeffrey F.; Chandran, Rakesh S.; Frank, Daniel L.; Wycoff, Stephanie B.; Brown, Amy; Parkhurst, James A. (2020)
    Integrated pest management (IPM) is the approach emphasized in this guide; some aspects of IPM are incorporated throughout, although this guide mainly deals with the chemical component of IPM. IPM combines biological control from predators with selective chemical application for maintaining pest populations below economic threshold levels. This approach requires that growers give careful consideration to the selection, application rate and timing of chemical sprays. The degree of integration achieved will vary according to the management ability, training and objectives of the orchardist. Inadequate monitoring or implementation of IPM practices will lead to unsatisfactory results. In order to encourage the biological control components of the program, growers must consider the toxicity of chemicals to predators (Table 9, page 59) in addition to their efficacy against fruit pests (Tables 7 and 8, pages 56-58)...
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    2021 Home Grounds and Animals PMG - Author Contact List
    Askew, Shawn D.; Wycoff, Stephanie B.; Bergh, J. Christopher; Bush, Elizabeth A.; Day, Eric R.; Del-Pozo, Alejandro; Derr, Jeffrey F.; Frank, Daniel L.; Hansen, Mary Ann; Hong, Chuan X.; Laub, Curtis A.; McCall, David S.; Miller, Dini M.; Nita, Mizuho; Parkhurst, James A.; Paulson, Sally L.; Pfeiffer, Douglas G.; Rideout, Steven L.; Wilson, James; Yoder, Keith S. (Virginia Cooperative Extension, 2021-02-12)
    This is a chapter of the 2021 Home Grounds and Animals PMG. This 2021 Virginia Pest Management Guide provides the latest recommendations for controlling diseases, insects, and weeds for home grounds and animals. This publication contains information about prevention and nonchemical control as alternatives to chemical control or as part of an integrated pest management approach. The chemical controls in this guide are based on the latest pesticide label information at the time of writing. Because pesticide labels change, read the label directions carefully before buying and using any pesticide. Regardless of the information provided here, always follow the latest product label instructions when using any pesticide. Commercial products are named in this publication for informational purposes only. Virginia Cooperative Extension does not endorse these products and does not intend discrimination against other products that also may be suitable.
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    2021 Home Grounds and Animals PMG - Home Fruit
    Pfeiffer, Douglas G.; Bergh, J. Christopher; Nita, Mizuho; Yoder, Keith S. (Virginia Cooperative Extension, 2021-02-12)
    This is a chapter of the 2021 Home Grounds and Animals PMG. This 2021 Virginia Pest Management Guide provides the latest recommendations for controlling diseases, insects, and weeds for home grounds and animals. This publication contains information about prevention and nonchemical control as alternatives to chemical control or as part of an integrated pest management approach. The chemical controls in this guide are based on the latest pesticide label information at the time of writing. Because pesticide labels change, read the label directions carefully before buying and using any pesticide. Regardless of the information provided here, always follow the latest product label instructions when using any pesticide. Commercial products are named in this publication for informational purposes only. Virginia Cooperative Extension does not endorse these products and does not intend discrimination against other products that also may be suitable.
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    2021 Home Grounds PMG - Index
    Askew, Shawn D.; Wycoff, Stephanie B.; Bush, Elizabeth A.; Day, Eric R.; Del-Pozo, Alejandro; Derr, Jeffrey F.; Frank, Daniel L.; Hansen, Mary Ann; Laub, Curtis A.; McCall, David S.; Miller, Dini M.; Nita, Mizuho; Parkhurst, James A.; Paulson, Sally L.; Pfeiffer, Douglas G.; Rideout, Steven L.; Wilson, James; Yoder, Keith S.; Hong, Chuan X. (Virginia Cooperative Extension, 2021-02-12)
    This is a chapter of the 2021 Home Grounds and Animals PMG. This 2021 Virginia Pest Management Guide provides the latest recommendations for controlling diseases, insects, and weeds for home grounds and animals. This publication contains information about prevention and nonchemical control as alternatives to chemical control or as part of an integrated pest management approach. The chemical controls in this guide are based on the latest pesticide label information at the time of writing. Because pesticide labels change, read the label directions carefully before buying and using any pesticide. Regardless of the information provided here, always follow the latest product label instructions when using any pesticide. Commercial products are named in this publication for informational purposes only. Virginia Cooperative Extension does not endorse these products and does not intend discrimination against other products that also may be suitable.
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    Apple Pollen Tube Growth Rates Are Regulated by Parentage and Environment
    DeLong, Candace N.; Yoder, Keith S.; Combs, Leon; Veilleux, Richard E.; Peck, Gregory M. (American Society For Horticultural Science, 2016)
    A greater understanding of apple (Malus domestica) pollen tube growth rates can improve crop load management in commercial orchards. Specifically, applications of caustic bloom-thinning chemicals need to occur when enough, but not too many, flowers have been fertilized to achieve crop load densities that balance yields with marketable fruit sizes. In this study, the pollen tube growth rates of five crabapple (Malus sp.) cultivars were measured in the styles of three maternal cultivars at 12, 18, 24, and 30 °C after 24 hours in a growth chamber. Pollen tube growth rates were greatest for ‘Selkirk’ and ‘Thunderchild’ at 12 °C, and greatest for ‘Indian Summer’, ‘Selkirk’, and ‘Thunderchild’ at 24 °C. Pollen tube growth increased with increasing temperatures until 24 °C. There were minimal pollen tube growth rate increases between 24 and 30 °C. Overall, ‘Snowdrift’ had the slowest pollen tube growth rate of the five evaluated crabapple genotypes. At 24 and 30 °C, ‘Indian Summer’ and ‘Thunderchild’ pollen tubes reached the base of the style most frequently, and ‘Snowdrift’ pollen tubes the least frequently. Pollen tube growth rate was also influenced by the maternal cultivar, with Golden Delicious having relatively faster pollen tube growth than Fuji at 24 and 30 °C. Interactions among paternal and maternal genotypes as well as temperature after pollination reveal complex biological and environmental relationships that can be used to develop more precise crop load management strategies for apple orchards.
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    Brown Rot on Peach and Other Stone Fruits
    Bush, Elizabeth A.; Yoder, Keith S. (Virginia Cooperative Extension, 2018-09-11)
    Describes brown rot disease, its life cycle and its effects of fruit trees and crop yields. Also discusses cultural and chemical methods of control.
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    Brown Rot on Peach and Other Stone Fruits
    Bush, Elizabeth A.; Yoder, Keith S.; Smith, Alson H. (Virginia Cooperative Extension, 2009)
    Describes brown rot disease, its life cycle and its effects on fruit trees and crop yields. Also discusses cultural and chemical methods of control.
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    Characterization of Fungicide Resistance in Venturia inaequalis Populations in Virginia
    Marine, Sasha Cahn (Virginia Tech, 2012-03-28)
    Apple scab (causal organism: Venturia inaequalis) is an economically devastating disease of apples that is predominantly controlled with fungicides. Of the chemical classes currently available, the sterol-inhibiting (SI) and strobilurin (QoI) fungicides are the most commonly used. Recent observations indicate that V. inaequalis populations in Virginia have developed resistance to myclobutanil and other SIs. However, little is known about the frequency and distribution of SI and QoI resistance in Virginia's scab populations. The first objective of this research was to evaluate V. inaequalis populations in Virginia for SI and QoI resistance. Fungal isolates were collected from experimental orchards at the Alson H. Smith Jr., Agricultural Research and Extension Center (AHS AREC) and from commercial orchards in Virginia and Maryland. Sensitivities were determined by assessing colony growth at 19°C on potato dextrose agar (PDA) amended with 0 or 1.0 µg ml-1 of myclobutanil (SI) (N=87) or trifloxystrobin (QoI) (N=25) at 28 days. A range of fungicide sensitivity was observed for both chemical classes. The second objective of this research was to monitor the temporal dynamics of SI resistance over five sequential field seasons. To monitor shoot growth, neon rubber bands were placed over actively growing shoot tips following myclobutanil application or sample collection. Fungal isolates were collected from the same trees from 2007 through 2010 (N=176) and compared with isolates collected from wild apple seedlings (N=3). A continuum of SI resistance was observed for each year, and the V. inaequalis population exhibited a baseline shifted toward reduced sensitivity. The third objective of this research was to examine the spatial distribution of SI fungicide resistance within the tree canopy in a lower-density orchard (less than 150 trees A-1). Leaves collected from larger trees (>8m) in a lower-density orchard at the AHS AREC were analyzed for manganese deposition, pre- and post-mancozeb application. Fungal isolates (N=105) were collected from several locations within the canopy in replicated trees in the same orchard. Weather sensors also monitored the microclimates within those tree canopies. Spray deposition, microclimate and SI resistance were influenced by canopy location. The fourth objective of this research was to investigate potential SI resistance mechanisms. Previously classified isolates were screened for point mutations within the CYP51A1 gene (Appendix C), differences in polymorphic bands (alleles) (Appendix D), and differences in metabolism of myclobutanil (Appendix E). The consensus sequences for the CYP51A1 gene were identical for all isolates tested (N=9), and results from amplified fragment length polymorphism experiment (N=82) were inconclusive. There were, however, significant differences among incubation time and myclobutanil concentration in the bioassay (N=11). Our results indicate that myclobutanil is still an effective compound for control of apple scab in many areas of Virginia.
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    Chemicals for the control of diseases and weeds of commercial tree and small fruits
    Drake, Charles R.; Yoder, Keith S. (Virginia Cooperative Extension Service, 1979-01)
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    Chemicals for the control of diseases, insects, and weeds of commercial tree and small fruits
    Drake, Charles R.; Yoder, Keith S.; Horsburgh, Robert L. (Robert Laurie), 1931- (Virginia Cooperative Extension Service, 1981-01)
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    Commercial Small Fruits: Disease and Insects. p. 2-1 – 2-40. In: 2016 Pest Management Guide for Horticultural and Forest Crops
    Pfeiffer, Douglas G.; Johnson, C.; Yoder, Keith S.; Bergh, J. Christopher (2016)
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    Commercial Small Fruits: Disease and Insects. p. 2-1 – 2-40. In: 2017 Pest Management Guide for Horticultural and Forest Crops
    Pfeiffer, Douglas G.; Johnson, C. S.; Yoder, Keith S.; Bergh, J. Christopher (2017)
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    Comparison of mixed fungicide schedules for broad spectrum disease control on Stayman, Idared, and Granny Smith apples, 2016
    Yoder, Keith S.; Cochran, A. E. II; Royston, W. S. Jr.; Kilmer, S. W.; Engelman, A. G. F.; Kowalski, A. L.; Repass, J. K. (APS, 2017-05)
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    Control of powdery mildew and other diseases by alternating fungicide schedules on Idared apple, 2017.
    Yoder, Keith S.; Cochran, Allen; Royston, William; Kilmer, Scott; Kowalski, Abby (APS, 2018-05-01)
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    Disease and weed control for tree and small fruits
    Drake, Charles R.; Yoder, Keith S. (Virginia Cooperative Extension Service, 1977-01)
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    Disease control and phytotoxicity by treatments applied to Redhaven peach, 2016
    Yoder, Keith S.; Cochran, A. E. II; Royston, W. S. Jr.; Kilmer, S. W.; Engelman, A. G. F.; Kowalski, A. L. (APS, 2017-05)
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    Disease control and phytotoxicity by treatments applied to Redhaven peach, 2017
    Yoder, Keith S.; Cochran, Allen; Royston, William; Kilmer, Scott; Kowalski, Abby (2018-05-01)