Handouts from the 2021 Miller Research Potato Pest Management Seminars

Handouts from the 2021 Miller Research Potato Pest Management Seminars

Miller Research LLC held its annual potato pest management seminar as a series of virtual meetings on February 16, 18, 23, and 25, 2021. Thank you to all who attended, participated, and provided feedback. Handouts of the PowerPoint presentations and links to the recordings are provided here.


Managing Fusarium Dry Rot
Options for managing Fusarium dry rot in the seed and at harvest, including seed handling, seed treatment, variety susceptibility, and post-harvest fungicide use.


Rhizoctonia Canker and Black Scurf
We discussed the importance of seed- and soil-borne inoculum and the effect of seed treatments and in-furrow fungicides on disease development.


Powdery Scab and PMTV
Symptoms of powdery scab and PMTV were discussed, along with the challenges associated with management recommendations for minimizing scab and PMTV symptoms.
Link to Recording
Recording password: pW2!j2Bw


Managing Pink Rot and Pythium Leak
Management options for pink rot and leak are presented. New research on the relationship between phosphite application and irrigation timing, along with optimal phosphite timing based on plant growth stage was also shown.
Link to Recording
Recording password: m=j$iK2s


Foliar Disease Management and Managing Fungicide Resistance
We offered a virtual tour of the 2020 variety trial, showing the relative susceptibility of common russet cultivars to early blight/brown spot and white mold. We also discussed the strengths of different fungicide programs, emphasizing the importance of proper use to avoid the development of fungicide resistance.
Link to Recording
Recording password: c3K+dig3

Common Pests of Potatoes

Common Pests of Potatoes

I recently had the opportunity to speak at the Utah State University Vegetable IPM Winter Webinar Series (January 20, 2021). Nick Volesky and I talked about common insect and disease problems of potatoes. It wasn’t possible to discuss all diseases, or spend a lot of time on the diseases we did discuss, but we were able to give a thumbnail view of some common diseases. We briefly covered the following topics:

  • The role of seed certification
  • The importance of quarantines, eradication, sanitation, fertility, and proper irrigation
  • Fusarium dry rot
  • Rhizoctonia canker and black scurf
  • Late blight
  • Early blight
  • White mold
  • Pink rot
  • Pythium leak

A handout of the meeting slides is available here: Common_Pests_of_Potato_Diseases

The video of the meeting is available here: https://www.youtube.com/watch?v=0A9sey8av5k

Potato Disease Quiz

Potato Disease Quiz

Thank you to all who participated in the Potato Disease Quiz at the Idaho Potato Conference on January 22 and 23, 2020 in Pocatello, ID. Two people achieved a perfect score! Congratulations to Alan Malek and Shelbie Anderson and they were the winners of the Cabela’s gift cards sponsored by Gowan. Thank you to our sponsor and thanks to all those who participated!

2020 Idaho Potato Conference Disease Quiz

Answers to the quiz

Handouts from the Miller Research Potato Pest Management Seminar

Miller Research LLC held its annual potato pest management seminar on Tuesday, January 28, 2020, at the Historic Wilson Theater in Rupert, ID. Thank you to all who attended!

Disease Susceptibility in Russet Potato Cultivars
Eight varieties were evaluated for susceptibility to Fusarium dry rot, Rhizoctonia canker, powdery scab, early blight/brown spot, white mold, pink rot, and Pythium leak both with and without fungicides. This presentation shares the results collected to date.

Fungicides for Foliar Disease Management
This presentation showed results from 2019 fungicide trials targeting early blight, brown spot, white mold, and black dot. The current status of resistance to these fungicides an Alternaria solani was addressed.

Everyone Loses from Potato Bruises
What management practices contribute most to reducing bruise? Dr. Nora Olsen discussed field, tuber, and impact contributors to blackspot and shatter bruise and the implications on disease development (e.g. Pythium leak and Fusarium dry rot) and quality issues.

Late Blight – The Irish Potato Famine is Still with Us!
Late blight was reported in 2019. What are the chances we will see it in 2020? This presentation discussed the impact of the 2019 outbreak and measures to avoid disease in 2020.

Pink Rot Management
Some relatively new fungicides have been labeled for pink rot control. This presentation shared results from 2019 trials, provided the results of fungicide resistance monitoring in 2019, and showed how the interval between phosphite application and irrigation can affect phosphite fungicide performance.

Strobilurins for Early Blight Control in Potato

Strobilurins for Early Blight Control in Potato

Strobilurins for Early Blight Control in Potato

When Quadris was introduced for managing foliar diseases of potatoes in 1998, growers’ ability to control early blight increased dramatically.  Other strobilurin products have followed.  Recently fungicide resistance has been observed for isolates of the early blight fungus.  What does this mean for using strobilurin fungicides in the field?

 The attachment below is a research report from 2010 sponsored by the Idaho Potato Commission with support from private industry.  Different strobilurin fungicides were applied alone and evaluated for their effect on disease control, yield, and grade.  Not all strobilurin fungicides performed the same.  Read the report below to learn more.

Strobilurins for Early Blight Control in Potato

Managing Early Blight, 2012

Managing Early Blight, 2012

See how different fungicide regimes performed against early blight and white mold for disease control, yield, and economic return.

We utilized four applications on Russet Burbank to evaluate the impact of fungicide programs on early blight control.  We reduced our foliar nitrogen applications in order to exaggerate the effect of early blight.    

In summary, many programs provided adequate early blight control.  However, programs with Luna Tranquility provided the highest degree of both early blight and white mold control.  When Endura was first introduced it was highly effective on these two diseases.  In recent years early blight control has been compromised because of fungicide resistance of the early blight pathogen to boscalid.  It is possible that this same thing could happen to Luna Tranquility.  Bayer has included Scala as part of Luna Tranquility product to help prevent resistance. Unfortunately, Luna Tranquility may not be an option for Pacific Northwest growers in 2013 due to MRL issues in Pacific Rim countries.

Another interesting observation was that programs with Quash increased yield. Quash provided only moderate control of early blight control, moderate increase in plant vigor, and did not control white mold.  Yet, total yield was increased.  It will be interesting to see if these effects are consistent over more years.

Summary observations: 

  1. Ten programs increased total yield compared to the untreated check (3-4, 9, 11-13, 16, 17, 20, and 26).  All three programs with Quash increased yield (12, 16, and 17) despite moderate disease control.
  2. The Vertisan/Aproach program (26) increased vigor and yield.
  3. The Luna Tranquility and Vertisan/Aproach programs resulted in the most effective early blight control (4, 7, 8, and 26).
  4. Ten treatments significantly reduced white mold compared to the untreatedLuna Tranquility (4, 7, and 8), many of the Endura treatments (2-3, 6, 10-11), and Rovral treatments (14 and 15) significantly reduced white mold.  No white mold was observed in the Endura/Scala treatment (6).  
  5. Bravo (5), Priaxor followed by Echo Zn (13), Quadris Top and Revus Top rotated with Bravo (19 and 21), GWN-10126 and GWN-10127 (23 and 24), and Tanos/Manzate (25) increased white mold compared to the untreated
  6. Omega Top MP did not reduce white mold
  7. All but one program increased vigor over the untreated check.  The Vertisan-Aproach treatment was the most vigorous treatment.