Cream Leaf What?

Cream leaf what? That's the exact response I've heard from superintendents over the past several weeks when I tell them their ultradwarf bermuda putting greens have a disease known as cream leaf blight. To answer your first question, cream leaf blight is not a new pathogen to turfgrass. It has been documented on creeping bentgrass and tall fescue. As more ultradwarf bermudagrass replaces creeping bentgrass for putting surfaces here in North Carolina, we will likely observe more new diseases. This disease has been diagnosed on both 'Champion' and 'Mini Verde' and we are in the process of complete confirmation of the causal fungus via DNA analysis.

 

Typical white patch symptom observed on ultradwarfs
in December/January in North Carolina

Cream leaf blight is caused by the same pathogen that causes pink patch, Limonomyces roseipellis. Pink patch is often found in close association with red thread, which is caused by the fungus Laetisaria fuciformis. Pink patch and cream leaf blight vary slightly in their morphological features, which we are able to detect under the microscope. For those of you who are plant pathology geeks, pink patch produces clamp connections and cream leaf blight does not. Otherwise, from what we've observed, the two appear identical in the field and we will most likely refer to it as cream leaf blight since that seems to match the stand symptoms the best. One unique characteristic is the mycelium will twist into "rope" like structures, as seen below.

Mycelium twisting into "ropes" for both cream leaf blight and pink patch (25x)

Close up of cream leaf blight hyphae twisting into a "rope" (200x)

While we don't know much about cream leaf blight on bermudagrass yet, we have only observed cosmetic damage and nothing that leads to turf loss or significant reduction in playability. We have been recommending fungicide applications of products like 26GT, ProStar, Heritage, Insignia, or Disarm since they have been proven performers with pink patch/red thread complexes.

If you are observing this type of symptom at your course and have questions, feel free to contact us!

The Rundown

After a relatively quiet June at the NC State Turf Diagnostics Lab, turf samples have been rolling in during the month of July. Right after the record breaking heat wave experienced by North Carolina and much of the country, it seemed as if delivery trucks were backing up and dumping cardboard boxes of all shapes and sizes chocked full of ailing turfgrass samples.

One of the most common questions I get from golf course superintendents that I speak with on a weekly basis is "What are you seeing in the lab?" Well, here you go! Here's a rundown of the most common diagnoses we've made over the past two weeks.


Creeping Bentgrass Putting Greens

1. Pythium root rot
2. Fairy ring
3. "Warm-weather" brown patch (Rhizoctonia zeae)
4. Yellow spot
5. Anthracnose

Home Lawns

Zoysiagrass

1. Curvularia leaf spot

Bermudagrass

1. Heat/drought stress

Tall Fescue

1. Brown patch

Pythium blight of bermudagrass putting greens

Following recent periods of wet, cloudy weather we've had several reports of a disease appearing on bermudagrass putting greens. The symptoms are a rapid foliar blight that initially has a purple coloration but then fades to tan. Spread on mowers or in drainage patterns usually occurs as well. Many superintendents assume that this is leaf spot, which of course is a common bermudagrass disease during wet weather in the fall. I have to admit that the first time I saw this I also thought it was leaf spot. But I was wrong - it is Pythium blight.



Pythium blight in October? Yes, you read it correctly, it is Pythium blight in October.

There are a lot of Pythium species that can infect grasses. Most people are familiar with P. aphanidermatum that causes Pythium blight on the cool season grasses during hot summer weather. However, there are other Pythium species that grow during cool or cold weather. We don't know what species is causing this outbreak yet, but obviously it grows well during cool weather and has a competitive advantage over the bermudagrass under these conditions.

Fungicide treatments may not always be necessary to control Pythium blight on bermudagrass, as dry and sunny weather usually put a stop to it very quickly. However, if the forecast is calling for extended periods of wet and cloudy weather, an application might be a good idea. Any strong Pythium fungicide should do a good job.