Pythium Root Rot: History Repeating?

The summer of 2010 shouldn't be too distant of a memory for most and if you remember correctly, most of NC ended May on a very wet note. This was followed by one of the hottest summers on record. This series of events led to widespread cases of Pythium root rot on creeping bentgrass putting greens, especially for those who did little to nothing to protect their roots from Pythium during May.

With all that being said, you should be applying products for Pythium root rot prevention RIGHT NOW.  Doing so now will save you money and headaches come summer.

For more information about Pythium root rot, including control recommendations, click here.

Remember that Pythium root rot is a soil disease, so you MUST water your applications in to be effective.

May 2012 Rainfall Total

May 2011 Rainfall Total

May 2010 Rainfall Total

Severe Large Patch Outbreaks in NC

You know it's officially spring in North Carolina when there are giant patches of brown grass in bermudagrass, centipedegrass, St. Augustinegrass, and zoysiagrass. These giant patches of brown grass are better known as large patch, caused by the fungus Rhizoctonia solani, and if you've ever had an outbreak of this disease, you now know why the disease was coined large patch.

What you may not know however, is what your control options are this time of year. You shouldn't worry too much if you have this disease on bermudagrass. Bermudagrass tends to grow out of the damage once the temperatures are consistently warmer and the daylight longer.

As for our other warm-season friends, damage tends to be most severe on centipedegrass and recovery may take all summer in extreme cases. Unfortunately, there isn't much you can do to make for a magical recovery. We rarely recommend fungicides for large patch in the spring of the year, however in worst case scenarios, a fungicide application might help prevent the disease from spreading further. Fungicide applications are best when they are applied preventatively in the fall. If you choose to spray a fungicide this spring, don't expect a miracle to happen overnight. Also, remember that recovery will be even slower and tougher if you've applied a DNA type of herbicide as your pre-emerge for summer weeds.

In most cases, the best thing is to stay the course with management practices that will encourage each type of grass to do well. In severe cases, treating damaged areas like a new establishment with light and frequent fertilizer and water inputs may help encourage faster lateral spread. This doesn't mean you should apply more fertilizer, just smaller doses more often. Applying too much fertilizer will make the disease worse this fall!

Finally, be sure to map the affected areas now while they are clearly visible. You will save yourself some money this fall by spot treating these areas instead of having to make a whole property application, since the disease tends to reappear in the same areas.

For more information about large patch, click here.

For more information about warm-season grass maintenance, click here.

Status Update: The Show Will Go On

Beginning February 1, I've accepted a new position with Syngenta as a Senior Technical Field Representative for Turf and Landscape. I'll be covering the Southeastern US and will stay in the Raleigh area.

The Turf Pathology Program at NC State has a long, proud history, dating back to the 1970s with Leon Lucas. I wanted to assure everyone that this program will continue to operate as normal (perhaps even better without my interference) during the transition period until the faculty position can be refilled:

• Lee Butler will continue to oversee the Turf Diagnostics Lab as he has since 2005. For information on how to submit a sample, visit the website www.turfpathology.org. 
• Mike Soika will continue to run the Fungicide Evaluation Program to gather valuable data on the performance of new and experimental fungicides.
• Bangya Ma, Alex Putman, and Joseph Roberts will continue their research on dollar spot, bentgrass etiolation, and other important problems in the turfgrass industry today.

I want to sincerely thank everyone in the turfgrass industry for your support since my arrival in 2002. It has been a pleasure to work with all of you, and I am proud to look back on what we've been able to accomplish together. I am looking forward to the new challenges that lie ahead and to maintaining a close relationship with this great industry in my new role with Syngenta.

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.

It's Officially Fall! Treat Now for Spring Dead Spot!

So, your first question may be "Why on Earth are you telling me to apply fungicides for a spring disease in the fall and for something that will not show up for another 6-7 months?!"  The answer is simple.  The causal fungus, Ophiosphaerella spp., is active RIGHT NOW and you can bet it's infecting your bermuda and zoysia grass plants as I type this blog.  We know through years of research that fungicides are most effective when the soil temperatures are between  60 - 80°F in the fall of the year.

Average Daily Soil Temperature on 9/22/2011 via NC State Climate Office

As you can see by the map above, the time is right for preventative applications. However, choosing the right fungicide and applying at the right time will not result in acceptable levels of control if you do not apply them correctly.  Spring dead spot infects below ground plant parts.  With that being said, you must either water-in your fungicide applications IMMEDIATELY  with 1/4" of irrigation or apply with a carrier volume of 5 gal/water/1,000 sq. ft.  You need to be running your irrigation the moment the applicator is out of the way.  Do not wait until the following evening or night with your routine irrigation schedule or else you may be severely disappointed come next spring when these grasses green back up.

Just recently we have made some fantastic discoveries with fertilizers in regards to controlling this disease without having to use fungicides at all!  To learn more about this, please click here.

Also, if you haven't heard, Rubigan will be coming off the market in December of 2012.  Rubigan is one of the better fungicides available for spring dead spot control.  To learn more about this, click here.

To learn much more about spring dead spot, including control recommendations and images, please click here.

It’s Almost Time to Prevent Large Patch!

With soil temperatures starting to approach 70°F across portions of NC, now is the time to start thinking about treating for large patch.

Average Daily Soil Temperature on 9/14/11 from the NC State Climate Office

Large patch, which is caused by the fungus Rhizoctonia solani, is a common disease of centipedegrass, St. Augustinegrass, zoysiagrass, and bermudagrass grown for lawns, landscapes, golf turf, and athletic fields. Centipedegrass and St. Augustinegrass are particularly susceptible to this disease.

Symptoms of large patch appear in roughly circular patches from 2 feet up to 10 feet or more in diameter. The affected turf will initially be orange, yellow, or reddish-brown in color but will then turn tan and collapse to the ground. The disease can spread rapidly to encompass large areas of turf, and distinct circular patches may not be obvious in these cases.

Fungicides are available for large patch control, but they must be applied preventatively for best results. The first application should be made in the late summer or early fall when average daily soil temperatures are 70°F or below. Depending on your location and weather patterns, this can be anywhere from late August to late September.

One fungicide application will control minor cases of large patch, but two to three applications on a 4 to 6 week interval may be needed to control severe cases. Fungicides are not very effective once the symptoms of large patch appear. Curative applications will help to reduce further spread of the disease, but the affected turf will be very slow to recover.

Click here for more information about Large Patch, including images and specific control recommendations.

Getting ready for life without Rubigan

Is this what life will look like without Rubigan?

A lot of people have heard about Rubigan going off the market in December 2012. If you have questions or concerns, please check out yesterday's post on turfdiseases.org entitled "What will we do when Rubigan is Rubi-gone?".

We are planning a lot more spring dead spot research this fall in response to this issue, so we'll probably be in touch with some of you about the possibility of doing research at your facilities.