2021 Turf Diagnostics Lab Review
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Overall, total turfgrass samples submitted in 2021 to the NC State Turf Diagnostics Lab were higher (+3.5%) than samples submitted in 2020, likely in part due to no COVID related lab closures like we had in 2020 (52 days). As expected, the majority (80%) of our samples came from golf course putting greens. Creeping bentgrass/annual bluegrass putting green samples were up 9% while bermudagrass putting green samples were down 7% when compared to 2020. We chose to combine creeping bentgrass and annual bluegrass data due to the majority of these samples being pure creeping bentgrass and they typically have the same disease issues as annual bluegrass. For the data lovers out there, the breakdown with percentages being respective to 2020 and 2021 is creeping bentgrass (79% and 76%), annual bluegrass (14% and 14%), and creeping bentgrass/annual bluegrass mixture (7% and 10%).
Below you will find information regarding all golf course putting green samples submitted in 2021. Enjoy!
WARNING! – These charts only indicate the samples we have received in our lab here at NC State. The following post focuses mainly on data collected from golf course putting green samples (creeping bentgrass/annual bluegrass and bermudagrass).
We typically receive samples from cases that are very hard to diagnose in the field alone. Therefore, these charts don’t necessarily represent all of the major disease outbreaks, but illustrate issues that require the use of a microscope and/or expert confirmation. This is why you will see little to no diagnoses of diseases that are relatively easier to diagnose in person such as dollar spot, brown patch, etc.
First, let’s take a look at which cultivars and varieties we receive the most. This is NOT an indication of one being more susceptible to disease or problematic than another. This was compiled from all samples submitted in 2021 and would likely match any survey that asks “What do you have planted?”. Remember, we receive most of our samples from the southeastern United States.
Next, let’s take a look at actual disease diagnoses. If you remember from an earlier post, 35-40% of the time we do not find any active pathogens in samples. This could be due to any number of factors such as it never was a disease, it was a disease and the damage was done too long ago to detect, or it was a disease and you’ve suppressed it with your fungicide program. I’m looking right at you folks who send samples after spraying everything in the barn BEFORE you collect your samples!
As the industry in our area shifted towards ultradwarf bermudagrass putting greens during the past decade or so, creeping bentgrass samples appear to be leveling off for now.
Bent/Poa samples followed a fairly normal monthly distribution pattern with the majority of samples coming during the summer. We used to see a sharp increase in June and a sharp drop off in samples around September, however, in the past several years, these samples are showing up a little sooner in April/May and continue to trickle into our lab well into the fall and appears to be the new normal for now.
For the first time since we’ve started publishing these data, summer patch was the number one diagnosed disease last year. Typically, this blue ribbon goes to Pythium root rot. While it’s hard to say exactly why this is, we would like to think that turfgrass managers have gotten better at managing Pythium root rot through continuing education events, recent research, etc.
Now, think about all of the problems listed in the bar graph above. With the exception of summer patch and fairy ring when they create nice little rings, they can all look similar! It’s very hard to diagnose most of these biotic and abiotic diseases in the field with 100% accuracy without looking under a microscope or testing for high salt levels.
Also, receiving a diagnosis of “no pathogen found” is equally as valuable as receiving a disease diagnosis. There are lots of things that cause turfgrass quality to decline, don’t assume it has to be a disease. It should be noted that while we do not offer a service for a nematode assay, we do report root-knot and lance nematodes. They are easy to see because they are endoparasites (inside the roots) and don’t get washed away like ectoparasites (outside the roots) when we rinse soil away from roots to detect fungal pathogens.
The chart above shows when each disease was diagnosed for bent/Poa putting green samples. The smallest bars usually indicate only a handful of confirmed cases, whereas the larger bars represent many confirmed cases through that time period.
Same as last year’s report, we have added all of the diagnoses we made throughout the year to illustrate what we see and to include those that don’t make the top 10 list above. There were 18 different diagnoses in 2021 on creeping bent/Poa samples. This does not include a diagnosis of “no disease activity”.
While this is the inverse of the bent/Poa chart above, this graph shows the rise of bermudagrass putting green samples over the past several years due to the industry shift towards these grasses for putting green surfaces as mentioned previously and appears to be leveling off for the most part.
Bermudagrass sample submissions by month follow a very similar path each and every year. The problems are fairly well distributed throughout the year with spikes in the spring and fall as bermudagrass exits and enters dormancy respectively.
Just like in the past few years, take-all root rot (TARR) remains at the top of the list. We saw a significant increase in the incidence of this disease starting in fall of 2015 when weather conditions were abnormally wet and warm for extended periods of time. Just like bentgrass diseases, a lot of these can look alike and require a microscope to make an accurate diagnosis.It should be noted that while we do not offer a service for a nematode assay, we do report root-knot and lance nematodes because they are endoparasites (inside the roots) and easy to see/don’t get washed away like ectoparasites (outside the roots).
The chart above shows when each disease was diagnosed for bermudagrass putting green samples. The smallest bars usually indicate only a handful of confirmed cases, whereas the larger bars represent many confirmed cases through that time period. Just like 2020, we received a lot of mini-ring samples late summer through early fall in 2021 with a lot of those diagnoses being made over email and text messages via photos, which are not counted as physical samples as represented above. We believe mini ring is more severe under low fertility and it’s likely those affected may have lost more fertility than they realized during the extended rainfall periods prior to symptom development.
Above are all of the diagnoses we made throughout the year to illustrate what we see and to include those that don’t make the top 10 list above. There were 12 different diagnoses in 2021 on bermudagrass samples. This does not include a diagnosis of “no disease activity”.
Bottom line: As you can clearly see, both bentgrass and bermudagrass continue to have their fair share of disease issues!
If you would like to see this same information from recent years, please click the links below :