2022 Turf Diagnostics Lab Review

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Overall, total turfgrass samples submitted in 2022 to the NC State Turf Diagnostics Lab were higher (+16%) than samples submitted in 2021, which brings us back to a normal year since it was very close to our average over the past 15 years. As expected, the majority (75%) of our samples came from golf course putting greens, which is down 5% from 2021. Creeping bentgrass/annual bluegrass putting green samples were only down by 2% while bermudagrass putting green samples were only down 4% when compared to 2021. 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.

Below you will find information regarding all golf course putting green samples submitted in 2022. 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).

44% of all turfgrass samples came from North Carolina. 68% of all turfgrass samples came from the SE United States.

22% of all creeping bentgrass/Poa putting green samples came from NC. 38% of all creeping bentgrass/Poa putting green samples came from the SE United States.

47% of all bermudagrass putting green samples came from NC. 89% of all bermudagrass putting green samples came from the SE United States.

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 2022 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. This is why it is very important to collect your samples for disease diagnosis before they are sprayed (please and thank you!).

As the industry in our area shifted towards ultradwarf bermudagrass putting greens during the past decade or so, creeping bentgrass samples continue to hold steady at their current level of submission rate over the past several years.

Bent/Poa samples followed a fairly normal monthly distribution pattern with the majority of samples coming during the summer. The difference this year was that we received more samples in August where we typically see the most submissions in July. This is best illustrated in the graph below when compared to the 14-year average. This shift likely has everything to do with the “environment” side of the disease triangle. Since our clients are widespread, it’s hard to pinpoint any specific weather pattern. Our area had below normal rainfall in July with above average rainfall in August and that likely had an impact on this outcome. We all know how much fungi love moisture!

Summer patch was the winner last year, however the champ Pythium root rot is back on the podium at number 1. High soluble salt made a big move up to 2nd place, likely due to very dry conditions in certain areas we serve. The remainder of the top-10 is fairly typical. It should be noted that majority of rapid blight diagnoses come from out west in states such as California, Nevada, 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 2022 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 have reached a plateau for now.

Bermudagrass sample submissions by month follow a very similar path each and every year in general. However, in the graph below you can see we received more submissions at green-up than normal, less than normal during the summer, and the dormancy wave was a month later than normal. This likely has everything to do with weather patterns and just like with bent/Poa, it can be difficult to put our finger on the exact cause given we have clients over such a wide area.

Now that we have collected a lot of data on these grasses, based on a 14-yr average we can now see there are 3 distinct times of the year when bermudagrass samples are submitted to our lab for both biotic and abiotic reasons. The first wave is at green-up in the spring, the second wave is mid-summer, and the third wave is during the onset of dormancy. While the first and third waves make sense, the second wave has peaked our curiosity. We are going to investigate this further this year with some research aimed at better understanding root and biomass production by the major cultivars in our region … stay tuned!

Just like in the past few years, take-all root rot (TARR) remains at the top of the list. Pythium root rot continues to make its way towards the top of this list. It gets overlooked by some due to thinking it only occurs on creeping bentgrass putting greens, however it is becoming more and more common. This could be related to aging surfaces in our area that are holding more water due to accumulated organic matter, however it was shown through research at the University of Florida by Dr. Mengyi Yu and Dr. Billy Crow that certain Pythium species are associated with nematode feeding and may not be the primary causal agent. In a lot of cases where I diagnose Pythium root rot I also encourage those clients to submit samples to a nematode lab for an assay. It is very common for me to see severely stunted root systems associated with Pythium activity in bermudagrass samples. Either way, we often see positive outcomes in turf quality when good Pythium fungicides are used in these situations.

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 and 2021, we received a lot of mini-ring samples late summer through early fall in 2022 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 16 different diagnoses in 2022 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 :

2021

2020

2019

2018

2017

2016

2015