Yes, the title is correct, I am new to the Turf Diseases blog. The bloggers who you have been reading over the last couple of years have invited me to contribute to this effort. I sure appreciate the invitation and hope that I can present some useful information to increase your success in managing turfgrass diseases.
Before I get into some updates from my area, I wanted to just take some space to introduce myself. I am a native of western New York State (I grew up in the Finger Lakes region). I received my B.S. in Biology from the State University of New York, College at Geneseo (SUNY Geneseo). I then moved to North Carolina and completed my M.S. and Ph.D. degrees in plant pathology from North Carolina State University. I am currently an assistant professor of turfgrass and horticultural crop pathology in the Department of Entomology and Plant Pathology at Oklahoma State University. I have been on the faculty at OSU for 4 years now. I specialize in epidemiology (study of plant disease epidemics and how to control them) and disease forecasting systems for plant diseases. I have developed and/or tweaked several disease advisory systems for various crops including turfgrass (more on that in a future post.) While I am not exclusively a turfgrass pathologist, I spend about 75% of my time diagnosing, studying, and delivering information about turfgrass diseases. I also have responsibilities for other crops such as ornamentals, grapes, pecans, and stone fruits. Some of you might think that all of these responsibilities might hinder my ability to be an expert in the turfgrass pathology field, I would argue otherwise. I believe that my experiences in diagnosing and managing disease of other crops give me a unique perspective when it comes to studying turf diseases and developing recommendations to manage them. I hope that my broad background and knowledge of disease management in many cropping systems will translate to useful information for you in these blogs.
Well, enough about me. I’m sure all of you are curious as to what has been happening in Oklahoma. Last week we hosted our first ever Turfgrass Pest Management Field Day. We concentrated mostly on turf disease and weed research, but also heard about Zoysiagrass mite from Dr. Nathan Walker, Turfgrass IPM Specialist. Dr. Walker also spoke about spring dead spot research at OSU and also new research on nematode management in bentgrass putting greens. Dr. Dennis Martin, turfgrass specialist, spoke about creeping bentgrass evaluations for dollar spot resistance. Dr. Justin Moss, turfgrass water management and environmental impact specialist, spoke about annual bluegrass control on creeping bentgrass greens using some new experimental herbicides. I finished things off with research updates on dollar spot in creeping bentgrass putting greens, brown patch in tall fescue, and large patch of Zoysiagrass. We had about 50 in attendance despite the near 100 F temperatures. We would like to thank all who attended and look forward to another successful Turf Pest Management Field Day in the Future. I will summarize some of the research presented at the field day in some subsequent posts.
The OSU Turfgrass Diagnostic Laboratory has been busy over the last couple of weeks. We have been receiving quite a few creeping bentgrass samples. This is not surprising considering that we have topped out between 90 F and 100 F every day for the past 20 days! Over the last month we have seen some stressed bentgrass succumbing to the heat and also some typical diseases such as Pythium blight, fairy ring, spring dead spot on bermudagrass, and nematodes on creeping bentgrass putting greens coming into the lab. The latter is most troublesome as we had a tough time last season with nematodes on putting greens in Oklahoma combined with the heat. All of this heat early on, not only is going to stress the bentgrass plants, but will also encourage rapid increases in nematode populations, which further stress creeping bentgrass. In a recent submission that arrived in the turf diagnostic lab from within the state of Oklahoma, a nematode extraction was performed (sugar flotation method using 100 cc of soil) and the following nematode populations were identified in two different putting greens (their corresponding action thresholds are also indicated).
Sting nematode - 76/100 cc soil; action threshold = 20/100 cc soil
Sheath nematode - 57/100 cc soil; action threshold = 200/100 cc soil
Ring nematode - 235/100 cc soil; action threshold = 500/100 cc soil
Stunt nematode - 396/100 cc soil; action threshold = 150/100 cc soil
Green # 2
Sting nematode - 11/100 cc soil; action threshold = 20/100 cc soil
Sheath nematode - 0/100 cc soil; action threshold = 200/100 cc soil
Ring nematode - 344/100 cc soil; action threshold = 500/100 cc soil
Stunt nematode - 794/100 cc soil; action threshold = 150/100 cc soil
The sting and stunt nematode populations are very worrisome this early in the season. As the season progresses, nematode populations will continue to increase resulting in further damage to roots. The combined effects of all of these various nematode species are also troublesome. Having several different populations causing various forms of damage to the roots of these plants will certainly have a negative effect on the condition of the greens later in the season.
No chemical control recommendations are currently available to the golf industry in Oklahoma (no certified Curfew applicators in Oklahoma), unless the manager has access to residual supplies of Nemacur. If a superintendent can get their hands on Nemacur, care should be taken applying this product and reapplication will likely be necessary to be effective at reducing the population of nematodes present. Cultural management should include raising mowing heights (.160 in. or more would be advised), adjustment of the frequency of mowing and rolling to reduce the amount of stress applied to the turf stand, and continued frequent, light applications of fertilizer and water are recommended. Any practice that reduces stress and damage to turf plants will encourage root growth and assist the plants in surviving the additional damage that nematode feeding causes. Superintendents are also encouraged to continue with a preventative fungicide program to manage fungal pathogens that can cause further damage and stress to the plants.
That's all I have for now! Until next time...