Pre- and Postinfection Activity of Fungicides in Control of Hop Downy Mildew Public Deposited

http://ir.library.oregonstate.edu/concern/articles/dn39x3333

To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 2015. The published article can be found at:  http://apsjournals.apsnet.org/loi/pdis

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  • Optimum timing and use of fungicides for disease control are improved by an understanding of the characteristics of fungicide physical mode of action. Greenhouse and field experiments were conducted to quantify and model the duration of pre- and postinfection activity of fungicides most commonly used for control of hop downy mildew (caused by Pseudoperonospora humuli). In greenhouse experiments, control of downy mildew on leaves was similar among fungicides tested when applied preventatively but varied depending on both the fungicide and the timing of application postinfection. Disease control decreased as applications of copper were made later after inoculation. In contrast, cymoxanil, trifloxystrobin, and dimethomorph reduced disease with similar efficacy when applied 48 h after inoculation compared with preventative applications of these fungicides. When fungicides were applied 72 h after inoculation, only dimethomorph reduced the sporulating leaf area similarly to preinoculation application timing. Adaxial chlorosis, necrosis, and water soaking of inoculated leaves, indicative of infection by P. humuli, were more severe when plants were treated with cymoxanil, trifloxystrobin, and dimethomorph 48 to 72 h after inoculation, even though sporulation was suppressed. Trifloxystrobin and dimethomorph applied 72 h after inoculation suppressed formation of sporangia on sporangiophores as compared with all other treatments. In field studies, dimethomorph, fosetyl-Al, and trifloxystrobin suppressed development of shoots with systemic downy mildew to the greatest extent when applied near the timing of inoculation, although the duration of preventative and postinfection activity varied among the fungicides. There was a small reduction in efficacy of disease control when fosetyl-Al was applied 6 to 7 days after inoculation as compared with protective applications. Trifloxystrobin had 4 to 5 days of preinfection activity and limited postinfection activity. Dimethomorph had the longest duration of protective activity. Percent disease control was reduced progressively with increasing time between inoculation and application of dimethomorph. These findings provide guidance to the use of fungicides when applications are timed with forecasted or post hoc disease hazard warnings, as well as guidance on tank-mixes of fungicides that may be suitable both for resistance management considerations and extending intervals between applications.
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  • Gent, D. H., Twomey, M. C., Wolfenbarger, S. N., & Woods, J. L. (2015). Pre- and Postinfection Activity of Fungicides in Control of Hop Downy Mildew. Plant Disease, 99(6), 858-865. doi:10.1094/PDIS-10-14-1004-RE
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  • description.provenance : Made available in DSpace on 2015-10-06T17:52:54Z (GMT). No. of bitstreams: 4 GentDavidBotanyPlantPathPrePostinfectionActivity.pdf: 1078733 bytes, checksum: 2eae196231d42067e9b00c7062e920ed (MD5) GentDavidBotanyPlantPathPrePostinfectionActivitySup.1.pdf: 338600 bytes, checksum: 600d3907651b5c01b29cb4de8f8ae1ff (MD5) GentDavidBotanyPlantPathPrePostinfectionActivitySup.2.pdf: 1742076 bytes, checksum: c42c5db3233b0387e77f7cebf912e664 (MD5) GentDavidBotanyPlantPathPrePostinfectionActivitySup.3.pdf: 194185 bytes, checksum: 35d254b7963cabf77a2c40b60af6a628 (MD5) Previous issue date: 2015-06
  • description.provenance : Submitted by Patricia Black (patricia.black@oregonstate.edu) on 2015-10-06T17:52:11Z No. of bitstreams: 4 GentDavidBotanyPlantPathPrePostinfectionActivity.pdf: 1078733 bytes, checksum: 2eae196231d42067e9b00c7062e920ed (MD5) GentDavidBotanyPlantPathPrePostinfectionActivitySup.1.pdf: 338600 bytes, checksum: 600d3907651b5c01b29cb4de8f8ae1ff (MD5) GentDavidBotanyPlantPathPrePostinfectionActivitySup.2.pdf: 1742076 bytes, checksum: c42c5db3233b0387e77f7cebf912e664 (MD5) GentDavidBotanyPlantPathPrePostinfectionActivitySup.3.pdf: 194185 bytes, checksum: 35d254b7963cabf77a2c40b60af6a628 (MD5)
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2015-10-06T17:52:54Z (GMT) No. of bitstreams: 4 GentDavidBotanyPlantPathPrePostinfectionActivity.pdf: 1078733 bytes, checksum: 2eae196231d42067e9b00c7062e920ed (MD5) GentDavidBotanyPlantPathPrePostinfectionActivitySup.1.pdf: 338600 bytes, checksum: 600d3907651b5c01b29cb4de8f8ae1ff (MD5) GentDavidBotanyPlantPathPrePostinfectionActivitySup.2.pdf: 1742076 bytes, checksum: c42c5db3233b0387e77f7cebf912e664 (MD5) GentDavidBotanyPlantPathPrePostinfectionActivitySup.3.pdf: 194185 bytes, checksum: 35d254b7963cabf77a2c40b60af6a628 (MD5)

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