2019 Diagnostics Lab Review

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Overall, total turfgrass samples submitted in 2019 to the NC State Turf Diagnostics Lab were nearly identical to total samples submitted in 2018 and only a few samples above our 10-year average. As expected, the majority (67%) of our samples came from golf course putting greens. Creeping bentgrass putting green samples were down 27% while bermudagrass putting green samples were up 36% when compared to 2018. Below you will find information regarding all golf course putting green samples submitted in 2019. Enjoy!

Client Distribution chart image

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 and bermudagrass).

Turfgrass Sample Origin chart image

48% of all turfgrass samples came from North Carolina. 75% of all turfgrass samples came from the SE United States (NC/SC/TN/AL/GA/FL).

Bentgrass Sample Origin chart image

37% of all creeping bentgrass putting green samples came from NC. 60% of all creeping bentgrass putting green samples came from the SE United States (NC/SC/TN/AL/GA).

Bermudagrass Sample Origin chart image

40% of all bermudagrass putting green samples came from NC. 81% of all bermudagrass putting green samples came from the SE United States (NC/SC/TN/AL/GA/FL).

We typically only receive samples from cases that are very hard to diagnose in the field alone. Simply put, we get the funky stuff! Therefore, these charts don’t necessarily represent the major disease outbreaks, but illustrate what causes the most head scratching if you will.

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 2019 and would likely match any survey that asks “What do you have planted?”. Remember, we receive most of our samples from the southeastern US with a lot of those coming from right here in North Carolina.

Common Cultivars chart image

Next, let’s take a look at actual disease diagnoses. If you remember from an earlier post, the majority of the time we do not find any active disease-causing organisms 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!Bentgrass Putting Green Samples chart image

As the industry in our area continues to shift towards ultradwarf bermudagrass putting greens, creeping bentgrass samples continue to decline. For the first time ever, we received more bermudagrass samples than creeping bentgrass samples in 2017. In 2019, bermudagrass returned to being the most submitted turfgrass species from putting greens.

2019 Bentgrass Putting Green Samples chart image

Creeping bentgrass samples followed a fairly normal monthly distribution pattern with the majority of samples coming during the summer in June, July, and August. We typically see a sharp drop off in samples around September, however in the past couple of years, creeping bentgrass samples continue to trickle into our lab well into the fall. This year was most likely due to record setting heat for our region in October with many locations recording their hottest day of year during this month.

2019 Bentgrass Putting Green Diagnosis chart image

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. Once again, remember that rarely do growers send us samples of things like fairy ring, brown patch, dollar spot, etc. that are relatively easy to diagnose in the field. Also, receiving a diagnosis of “no disease” 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 nematodes because they are so easy to see in samples.

Bentgrass Putting Green Diseases chart image

The chart above shows when each disease was diagnosed for creeping bentgrass 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.

Bentgrass Putting Green Samples chart image

While this is the inverse of the creeping bentgrass 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.

Bermudagrass PG Samples chart image

Bermudagrass sample submissions by month follow a very similar path each and every year. The problems are fairly well distributed throughout the year with subtle spikes in the spring and fall.

Bermuda Putting Green Diagnosis chart image

Just like in 2018, take-all root rot remains at the top of the list. We saw a significant increase in the occurrence 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. Our lab does not test for nematodes, however we will report root-knot nematodes when they are observed in high numbers because the attached females are very easy to see while all other nematodes go down the drain when we wash soil away from the roots for disease diagnosis.

Top 10 Bermudagrass Putting Green Diseases chart image

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. Finally, we received a lot of mini-ring samples late summer through early fall 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.

Bottom line: As you can clearly see, both bentgrass and bermudagrass have their fair share of disease issues!

If you would like to see this same information from recent years, please click the links below –

2015

2016

2017

2018