Barbara Shew V-C Peanut News Article Peanut Notes No. 177 2020

— Written By NC State Extension

The End of a Season

Barbara Shew

Department of Entomology and Plant Pathology

North Carolina State University

The late summer article for Peanut News is always been the hardest one for me to write. Usually the disease situation in September has not started to shape up by the time the article is due in early August. That appears to be the same situation this year, with a few ringers thrown in. I’m typing this as tropical storm Esaias is bound for North Carolina, with the outcome still unknown. And this is just one little bit of uncertainty in the middle of a pandemic and the hardship it means for many. But if all goes as planned, one thing is certain for me. This is the last article I will write for Peanut News. I retire from NC State on September 30 after working on peanuts and their diseases for about 40 years.

I started my career in peanut as a Ph.D. student working under Dr. Marvin Beute. He was a great mentor who made invaluable contributions to our understanding of peanut diseases, especially CBR. When I joined the lab in 1980, CBR was ravaging peanut fields across the state. My dissertation project was not on CBR, but students in Marvin’s lab were expected to pitch in when work needed to be done. Working alongside his students on CBR was a big part of my Ph.D. experience. The Beute lab’s work developed the foundations for CBR control still used today, and his close collaboration with Dr. Johnny Wynne lead the release of the first CBR resistant cultivar, NC 8C, in record time. This was followed later by NC 10C and Perry. Pat Phipps at Virginia Tech and Jack Bailey at NC State helped to tame CBR with fumigation. Now CBR problems are a rarity in North Carolina, probably due to longer and better rotations, host resistance, and possibly a natural build-up of antagonists in the soil.

Southern stem rot was my dissertation topic. At that time, fungicide options were not satisfactory and resistant cultivars were unknown. Stem rot seemed like a bit of a dead end in North Carolina because the damage often was hidden underground and unappreciated. I made some progress, but it was not until later that we had the tools to manage this disease. Folicur not only was the first fungicide really effective against stem rot in peanut, but trial results with Folicur (and others later) clearly showed that fungicides that control stem rot (and Rhizoctonia) consistently increase yield. Later, we were surprised to find that Bailey has stem rot resistance. Selection for CBR, TSWV or Sclerotinia blight probably inadvertently selected for stem rot resistance as well. With fungicides and resistance, stem rot control has improved considerably. However, the conditions that lead to stem rot problems are still not very well understood and timing sprays involves a lot of guesswork. I’ve worked on stem rot longer than any other peanut disease and still understand it the least.

My career continued as a post-doc working on leaf spots. A primary aim of this work was to identify leaf spot lines that could be used to breed leaf spot resistant cultivars. Working out the environmental conditions that favor leaf spot infections and development was another part of the puzzle. This work took many years of research in many places to come to fruition. Pat Phipps at Virginia Tech used the environmental data to develop a practical leaf spot advisory that we adapted into the current North Carolina advisory. In the meantime, Drs. Wynne, Stalker, and Isleib kept working toward developing leaf spot resistant breeding lines and cultivars. These efforts culminated in the release of Bailey, which had good resistance to early leaf spot. At the same time, industry developed effective new chemistry against leaf spot diseases, including Abound, Headline, and many others, with Miravis the latest in a long line of effective leaf spot fungicides. Observing the outstanding performance of these products in their early years was exciting. Unfortunately, leaf spots remain formidable foes, overcoming our best efforts at genetic and chemical control.

Jack Bailey was a friend and an unforgettable person. He was especially interested in finding solutions for Sclerotinia blight. He pushed hard for registration of fluazinam (Omega 500), which growers needed badly. He collaborated with Marvin Beute, Johnny Wynne, and later Tom Isleib and I to identify Sclerotinia blight resistant cultivars. Work on biological and cultural control followed, and my lab worked to understand Sclerotinia biology, resistance in peanut, and the environmental conditions that lead to Sclerotinia blight outbreaks. We were surprised to discover that Sclerotinia can be very active in hot weather and can become active earlier in the season than previously thought. We learned that timing sprays at the first outbreak of disease was the most effective way to control it. On the other hand, we found that late-season sprays had less benefit than expected. Sclerotinia blight remains my favorite peanut disease, with apologies to those who think “favorite disease” is a contradiction in terms!

I have been fortunate to have had so many talented colleagues over the years. Working with Tom Isleib was a great experience. His success as a breeder of Virginia-type peanuts is unmatched, but he’s also one of the most intelligent people I know, one of the funniest, and one of the most generous. David Jordan’s and Rick Brandenburg’s examples taught me how to be an effective peanut specialist. No one works harder for peanut growers than David. Growers could not ask for a more committed extension specialist, scientist, and advocate. It’s been a privilege to have had him and Rick as colleagues.

I firmly believe that peanut county agents are the best in the N.C. Cooperative Extension system. They’ve kept me honest with tough questions and inspire me with their dedication, breadth of knowledge, and willingness to learn.

Nothing I’ve done could have happened without the dedication of the staffs at the Rocky Mount and Lewiston research stations. I can’t thank them enough for their professionalism and patience.

I’m incredibly grateful for the opportunity to work in a job that has provided me with so much satisfaction over the years. There have been many times when I couldn’t believe that I was being paid to spend a beautiful day in the field while teasing apart the mysteries of peanut diseases. There were some miserably hot days too and days when everything seemed to go wrong. On those days, I would remind myself of the many growers and cooperators who had invested their time, energy, and support into the work we do. The trust growers place in us is truly humbling, and I can think of no greater honor than having a grower ask me for my advice. Thank you!

I hope before too long we can see each other again, face to face, in a peanut field. Until then stay safe and (nerd alert!) live long and prosper.