Detection of Phytopythium vexans in New Jersey Conifer Nurseries
Applied Research
Timothy Waller
Agriculture & Natural Resources County Agent III
Rutgers
Millville
Abstract
Oomycete diseases impact and limit production of virtually every plant on the planet, yet we are continually discovering new pathogens and species, lifecycle information, pesticide management patterns, and unravelling genetic relationships. Here one aspect of a recent USDA Specialty Crop Block Grant (USDA-SCBG) is evaluated, the very much unexpected detection of Phytopythium vexans, in multiple crops, locations, and production systems within New Jersey conifer nurseries, nursery stocks, and Christmas tree farms which challenged the research hypothesis that numerous oomycete species, primarily Phytophthora spp., are causing root diseases in NJ conifer nurseries. The main objective of the overall project was to map the oomycete species causing root diseases in NJ conifer nurseries. The isolation techniques utilized to detect oomycetes from roots via selective media and unique aerated off-site ‘bating/trapping’ detection techniques utilized for soil and waterway samples are discussed. The phylogeny (based on internal transcriber spacer gene loci (ITS4,6)) of collected isolates revealed a large proportion of Pp. vexans in addition to expected P. cinnamomi and P. cryptogea/drechsleri complex, species known to cause disease in conifers as well as numerous Pythium species (worthy of future exploration). This is particularly important because Pp. vexans has an enormous host range and could be a severe pathogen that has been going undetected (Ghimire & Baysal-Gurel, 2023) for some time. Additionally, many of the host detections may constitute First-Reports – pending completion of Koch’s Postulates and re-isolations from mapped sites. Although preliminary oomycide efficacy data is beyond the scope of this deliverable, it appears likely that Pp. vexans is considerably less responsive to many Phytophthora-centric oomycides, which may have profound impacts on current and future management strategies. This marks a huge leap forward in understanding the oomycete species impacting conifer nurseries in NJ and beyond.
Poster has NOT been presented at any previous NACAA AM/PIC
This poster is being submitted for judging. It will be displayed at the AM/PIC if not selected as a State winner. The abstract will be published in the proceedings.
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Authors: Timothy Waller, William Errickson
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Waller, T. Agriculture & Natural Resources County Agent III, Rutgers Cooperative Extension, New Jersey, 08332-9776
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Errickson, W. Agriculture and Natural Resources County Agent III, Rutgers Cooperative Extension, New Jersey, 07728-5033