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Volume 2 Issue 3, March 2021
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 IT/Diagnostician Meeting Highlights
By Tania Brenes-Arguedas, Jan Byrne, Chandler Day, and Karen Snover-Clift
On Jan. 12–14, 2021, CERIS hosted the NPDN IT/Diagnostician Meeting. This meeting was very different from previous years. For one, due to the COVID-19 restrictions, the meeting was hosted virtually. To accommodate differences in time zones, instead of two full days of work, we had three afternoons (or mornings if you were in Pacific time).
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Tomatillo (Physalis philadelphica) showing carryover injury due to the herbicide clopyralid (Stinger) — Reported as: Herbicide Injury G#4 Synthetic Auxin
New NPDN Guideline:
Reporting Herbicide Damage
Over the years, diagnosticians in the network had requested a plethora of new pest codes for different types of herbicide damage. There were many codes with herbicides listed specifically by active ingredient, such as 2,4-d, atrazine, dicamba, glyphosate, and mesotrione. If we kept using active ingredient names, it was soon going to become difficult to keep up with new herbicide names. One possible solution was to not differentiate and simply lump all herbicide damage into a single code. Instead, Dr. Erin Hill suggested a system used by weed scientists that groups herbicide injury by mode of action.
This system was implemented last year in the NDR pest dictionary, and a number of herbicide damage and resistance pest codes were made available. Dr. Erin Hill has now authored a guideline on how to enter herbicide injury/resistance diagnosis. You can view it online at https://www.npdn.org/herbicide_guidelines
Horseweed (Conyza canadensis) exhibiting resistance to the herbicide glyphosate (Roundup PowerMax) during a bioassay screening — Reported as: Herbicide Resistance G#9 Glyphosate. Note that glyphosate is the only herbicide in group 9 (EPSPS inhibitor SOA), which is why it is mentioned specifically in the code.
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Protocols and Validation Quick
and Useful Tips
Tips for identifying Rhizoctonia
By James Woodhall, University of Idaho, Parma and Lina Rodriguez Salamanca, Iowa State University
Rhizoctonia is a ubiquitous fungus, and members of the group contain many important plant pathogens. Rhizoctonia, in its most widely used but artificial sense, is considered a species complex that comprises several groups including the multinucleate Rhizoctonia solani (Thanatephorus cucumeris), binucleate Rhizoctonia species (BNR or Ceratobasidium species), and Waitea circinata (Table 1). Knowing the anastomosis group (AG) present is often essential for an accurate diagnosis and to provide recommendations as AGs can have different host ranges, fungicide sensitivity profiles, growth temperatures, and means of dispersal. They can even specialize in the plant part they colonize. For example, in potatoes, AG8 exclusively infects the roots, while AG3-PT can cause stem cankers and black scurf. Within each AG, there can be multiple subgroups assigned on various critera often unique to each subgroup, such as thiamine autotrophy, the ability to grow at 35°C (such as AG2-2IIIB), host range, and ITS sequence. García et al. (2006) provide an overview of subgroups and their hosts.
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Dawn Dailey O’Brien Retires!
By Karen L. Snover-Clift
After years of being in denial of Dawn Dailey O’Brien’s impending retirement date, and selfishly unwilling to envision daily life in her absence, COVID-19’s arrival stole what remained of my precious time with Dawn, and it prevented her Cornell University colleagues from sending her off with fanfare and a stroll down memory lane. To recognize and thank Dawn for her contributions to NPDN, I invite you to join me on that stroll now as I review her career and some of her greatest accomplishments.
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Resources for Diagnosticians
Electronic Grower Resources Online (e-GRO)
e-GRO is a clearing house for alerts about disease, insect, environmental, physiological, and nutritional disorders being observed in commercial greenhouses. Click to subscribe.
Check out this recent e-GRO article by Jean Williams Woodward of the University of Georgia.
Calonectria root, crown and cutting rots are less common but just as damaging as the more common pathogens causing root disease in greenhouse crops
Pest Lens
Pest Lens is USDA-APHIS-PPQ’s phytosanitary early warning system that collects and distributes new information on exotic plant pests and provides a web-based platform for documenting safeguarding decisions and resulting actions. Receive their weekly notifications by clicking subscribe at https://pestlens.info/.
Peer review highlights
Names of Phytopathogenic Fungi: A Practical Guide https://doi.org/10.1094/PHYTO-11-20-0512-PER
Evaluating Species in Botryosphaeriales https://doi.org/10.3767/persoonia.2021.46.03
Detection and Diagnostics of Fungal and Oomycete Plant Pathogens Plants journal Special Issue https://www.mdpi.com/journal/plants/special_issues/detection_diagnostics_fungal_oomycete_plant_pathogens
Conventional Gel Electrophoresis and TaqMan Probes Enable Rapid Confirmation of Thousand Cankers Disease from Diagnostic Samples https://doi.org/10.1094/PDIS-10-20-2258-RE
Boxwood Blight Disease: A Diagnostic Guide https://doi.org/10.1094/PHP-06-20-0053-DG
Rapid Detection of the Laurel Wilt Pathogen in Sapwood of Lauraceae Hosts https://doi.org/10.1094/PHP-06-20-0049-RS
Rapid Identification of Tropilaelaps Mite (Mesostigmata: Laelapidae) Species Using a COI Barcode-HRM https://doi.org/10.1093/jee/toaa330
Notable First Reports
First Report of Xanthomonas hortorum Causing Bacterial Leaf Spot of Lavender (Lavandula × intermedia) in Ohio https://doi.org/10.1094/PDIS-08-20-1684-PDN
First Report of Fusarium proliferatum Causing Necrotic Leaf Lesions and Bulb Rot on Storage Onion (Allium cepa) in Southwestern Idaho https://doi.org/10.1094/PDIS-06-20-1399-PDN
Rhizoctonia solani AG 2-2 IIIB Causing Root Rot of Onion in Idaho https://doi.org/10.1094/PDIS-08-20-1724-PDN
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Announcements
Planning Starting for the 2022 NPDN National Meeting
Save the date: The 2022 NPDN National Meeting will be held April 25–29, 2022, in sunny Davis, California.
We are now looking for NPDN members to volunteer for the different meeting planning subcommittees.
Find out how to volunteer to help us ensure that the meeting program and activities
are what the diagnostic community needs. Click here to see the different meeting planning subcommittees (login required *)
*If you do not have a NPDN member account to log in but you regularly contribute to NPDN
activities, contact your regional center to be added as a member.
New Lab Method Dictionary Entry
– National Data Repository
By Lina Rodriguez Salamanca and James Woodhall
A new lab method for Tissue Analysis is now available in the National Data Repository, as shown below.
Please note “tissue analysis” can be used for both nutrient and herbicide residue testing from plant tissue.
To submit new lab methods for consideration, contact lina@iastate.edu indicating need and examples of how the current lab methods have limitations that justify a new method. The lab method dictionary and definitions are available at https://npdn.ceris.purdue.edu/index.php (login required). The Dictionary Subcommittee discusses requests, and the Protocol and Validation Committee ratifies new methods and definitions.
GPDN Webinar Series
GPDN webinars continue through March 17. Find the schedule here.
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Submissions and Subscriptions
Submissions for publication in The NPDN Communicator are accepted on a rolling basis. The deadline for publication is the last day of the month. Submission and subscription details can be found here.
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