NC State Turf Pathology

Pythium Root Rot: History Repeating?

2012-05-25T11:07:00.000-07:00

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

2012-04-25T13:00:00.000-07:00

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

2012-01-17T13:20:00.000-08:00

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

2011-10-26T09:49:00.000-07:00

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!

2011-09-23T11:31:00.000-07:00

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!

2011-09-15T09:52:00.000-07:00

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 notvery 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

2011-09-15T09:12:00.000-07:00

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.

Do growth regulators and biostimulants cause yellow etiolation of creeping bentgrass?

2011-09-05T11:00:00.000-07:00

We've been seeing yellowing and etiolation of creeping bentgrass greens in North Carolina off and on since 2005. Some people are calling this 'bacterial wilt', but there are two problems with this name. First, no one has proven that this condition is caused by a bacteria. Second, and perhaps most obviously, wilt isn't one of the symptoms!

So, can we all agree to call it yellow etiolation instead of just slapping another erroneous name on it? I know that 'etiolation' is difficult to pronounce, but you can hear its correct pronunciation and practice along at thefreedictionary.com/etiolation.

Early on, I had a theory that biostimulants and/or growth regulators were involved in either causing this yellow etiolation or increasing its appearance. I wanted to share a couple of pictures recently sent to me by golf course superintendents that provide even more evidence of their role in this condition.

This first picture was taken at one of our research sites. Our plots were positioned in a ring around the cleanup pass of this green, and we asked them to avoid spraying our plots when they made certain applications to the greens. The area to the right that is declining severely received their sprays containing a biostimulant product and the growth regulator trinexapac-ethyl. As you can see very clearly, the areas NOT receiving these sprays are much more healthy than the areas that were sprayed.

This second picture was sent to me by a golf course superintendent in Pennsylvania. You are looking at a collar-height walkway between a green and a tee. The area to the left of the red dotted line received double applications of Primo, one along with the greens applications and another along with the tee applications. You can clearly see that the yellowing, etiolation, and thinning of the bentgrass is much more pronounced in the area receiving higher rates of Primo.

So what is going on here? To me, this is looking more and more like a physiological condition rather than a disease problem. We are still unable to consistently isolate any single pathogen, bacteria or otherwise, from turf exhibiting these symptoms. We are planning research to look at the influence of growth regulators and biostimulants on this problem. Until then, I suggest that superintendents who are battling this problem eliminate biostumulants from their programs and also avoid use of trinexapac-ethyl during periods of summer stress.

Program '11 Update: Stress

2011-09-01T14:07:00.000-07:00

A lot has happened since the last update I posted on July 22. We had record attendance of 650 at our NC State Turfgrass Field Day on August 10. Classes are in session, conference season is starting up, and we had an earthquake AND a hurricane in one week. I sincerely hope that everyone who was in the path of Hurricane Irene escaped severe damage.

From mid July to mid August was hot, humid, and stressful for bentgrass putting greens in North Carolina, with 18 days above 95 and 6 days above 100. The low temperature only dipped below 70 degrees once during this time.

We've made several changes to Program '11 in response to the prevailing weather patterns. In response to the severe stress imposed by the weather conditions, we decided to apply Signature + Daconil on August 1 instead of Stellar + Daconil. On August 15, the weather was cooling off and we decided to drop the Alude application and applied Spectro alone.

On August 29, in the wake of Irene, we applied Honor instead of Subdue + Fore. While there was some potential for Pythium root rot development in these wet conditions, we were more concerned about the explosion of dollar spot and brown patch we were observing in untreated areas on the research farm.

All of the programs have continued to provide excellent disease control. No significant amounts of dollar spot, brown patch, anthracnose, or Pythium root rot have been observed in the treated plots. The Bayer Program has continued to express more yellow spot symptoms as I reported in July. This program contains a lot of QoI fungicides, which we've found increase the intensity of yellow spot symptoms.

On July 25, Program 13, NC State Program, BASF Program and Program '11 all exhibited excellent turf quality. Beginning in early to mid July, all programs declined in their turf quality, except for the BASF program which actually continued to slightly improve. Plots treated with the BASF Program has significantly better turf quality than all others on August 16 and 22. The Syngenta Program improved in its turf quality and by August 29 was statistically similar to the BASF Program while all the others were significantly lower.

It is difficult to determine why the BASF Program held up so well during the hot and humid conditions of early July. These plots were treated with a tank-mixture of Segway, Iprodione Pro, and Daconil Ultrex on August 8, which may have helped to control some underlying Pythium root rot or other disease. Perhaps the application of Honor on July 11 helped to precondition the bentgrass for the oncoming stress as BASF promotes.

Program '11 Update: Yellow Spot

2011-07-22T11:00:00.000-07:00

As mentioned in a previous post, yellow spot has been particularly bad this year on creeping bentgrass putting greens. We have a lot of it in our Program '11 Trial area so we were able to assess how fungicide programs are influencing the disease.

It is interesting to note that the programs receiving chlorothalonil or mancozeb applications during May and June were relatively clean of yellow spot, especially the Syngenta, BASF, and Program '11 treatments. This is consistent with our past observations of effective yellow spot control with chlorothalonil and mancozeb.

For the most part, we stuck to our original plans for Program '11 during July. Most of the changes we make continue to be dictated by dollar spot pressure. We applied Disarm C instead of Honor on June 20 because the Honor was applied earlier on June 6. We also applied Signature + 26GT on July 5 instead of Signature + Daconil Ultrex because dollar spot was continuing to develop and we feared that Daconil alone would not provide sufficient control. Both of these changes may have turned out to be a mistake.

Turf quality dipped to 6 out of 9 in our Program '11 treatment on July 19. Turf in these plots was showing significant signs of stress, thinning, and algae invasion. On the other hand, the NC State Program was among the best treatments in the trial with turf quality of 7 out of 9. The Honor application on June 20 and the Signature + Daconil application on July 5 are most likely responsible for the increased turf quality provided by the NC State Program.

Now entering the 'No DMI Zone'

2011-07-18T07:45:00.000-07:00

Every year, we see a lot of golf course superintendents get into trouble by applying DMI fungicides to bentgrass or Poa annua putting greens during periods of hot weather. These products can cause severe damage to stressed cool-season grasses, and our general rule of thumb is that they should not be applied to putting green turf when temperatures above 90 are expected in the next two weeks. After a nice break in the weather late last week, temperatures are ramping up into the high 90's and I don't think we can count on seeing temperatures below 90 for quite some time.

There are few good reasons to apply a DMI fungicide during July and August anyway. Most of our summer diseases can be controlled very well with other chemistries that do not have these negative side-effects.

So, if you are considering an application of a DMI fungicide, ask yourself two questions: "Are my greens stressed? Are temperatures above 90 in the forecast?" If the answer to either of these questions is "Yes", then leave the DMIs on the shelf!

One exception is anthracnose; if you have Poa annua greens or older bentgrass varieties that are prone to anthracnose, a DMI application could be justified. The new-generation DMIs like metconazole, tebuconazole, and triticonazole have less injury potential on cool-season grasses and provide very good anthracnose control. Keep the rates low and tank-mix with chlorothalonil to minimize the chances for injury, thinning of the turf, and algae invasion.

Update on Bacteria in Creeping Bentgrass Greens

2011-07-08T13:59:00.000-07:00

In the last month, we've observed significant amounts of bacteria in 32 creeping bentgrass samples submitted to the Turf Diagnostics Lab. We isolated the bacteria in these samples and are identifying them by DNA sequencing and other techniques.

The good news first: the majority of samples contained bacteria that are known to be non-pathogenic to turf. We suspect that these bacterial infections occurred during aerification and topdressings performed after Memorial Day when it was very hot and humid. These non-pathogenic bacteria are not killing the plant directly but may be speeding up the dieback of leaves or tillers that were injured by these stressful practices.

We did isolate the plant pathogenic bacteria Acidovorax from 7 locations, most of which are in the Piedmont of North Carolina. The samples that contain Acidovorax are showing the symptoms of chlorosis, etiolation, and gradual thinning that I wrote about in previous posts. The caveat is that we're not isolating Acidovorax from all of the locations where these symptoms are present. As a result, we cannot be sure that this bacteria is the true cause of the symptoms.

Results from trial on L-93 in Raleigh. Rates are per 1000 sq ft.

We have ongoing trials at 2 locations where Acidovorax is present, and our preliminary data is presented here. First, a word on our rating scale. These ratings are on a 0 to 9 scale, where 0 equals no disease, 1 to 3 represents varying degrees of chlorosis, 4 to 6 represents chlorosis with varying degrees of thinning, and 7 to 9 represent severe thinning of the turf.

Results from trial on G-2 in Charlotte. Rates are per 1000 sq ft.

While we haven't found a silver bullet yet, we have noticed that Signature treatments seem to be helping. In the Raleigh trial, 8 oz of Signature applied 3 times has prevented the turf from thinning, although some chlorosis and etiolation is still evident. In the Charlotte location, plots treated with 8 oz of Signature 3 times have improved slightly, while all other plots have continued to thin.

Before you complain about the price of an 8 oz Signature spray: we don't set the prices, we're just trying to find something that works. We are continuing to evaluate other products and practices that may help to control this problem and will post regular updates on this blog as we learn more.

One important take-home message: just because a diagnostic lab sees bacteria in your bentgrass doesn't mean you have a bacterial disease. Most of the samples we've received have only contained non-pathogenic bacteria. The bacteria has to be isolated and identified in order to determine if it is a plant pathogen.

Program '11 Update: Dry and Cool

2011-06-29T17:52:00.000-07:00

It's been dry in Raleigh during most of June, and cool (compared to last year, at least) for the last couple weeks. Disease pressure on our 'A-1' bentgrass green has been relatively light as a result. Nevertheless, we still made several changes to Program '11:

Dollar spot pressure was still pretty high in early June, so instead of applying Disarm C on June 6 we applied Honor for its better activity against dollar spot. We skipped the application of Subdue Maxx that was planned for June 13 because of the dry conditions. Then on June 20 we applied the Disarm C that was originally planned for June 6.

All of the programs are providing good brown patch control. Dollar spot is still reducing turf quality in the Syngenta Program, but all other programs are providing very good turf quality this week.

For more information about our Program '11 Project, or to follow along on Facebook or Twitter, please visit our website turfpathology.org.

If it's yellow, just be mellow

2011-06-24T12:17:00.000-07:00

Rumors have been swirling around the golf industry over the last week about 'bacterial wilt'. For the record, I want to make it clear that we have diagnosed NO cases of bacterial wilt in North Carolina or any other state.

I repeat, we have diagnosed NO cases of bacterial wilt in North Carolina or any other state.

Yellow spot of creeping bentgrass.

We have seen suspicious amounts of bacteria in bentgrass expressing symptoms of yellowing, etiolation, and gradual thinning. We don't know if these bacteria are the cause of the problem or if they are a secondary invader. As a result, we don't know if this is an actual disease or not. For more information, see our recent blog post.

A severe case of yellow spot on creeping bentgrass.

'Bacterial wilt' is caused by Xanthomonas translucens and is primarily a problem on Poa annua but also occurred on 'Toronto' creeping bentgrass back in the 1980s. Bacterial wilt causes rapid wilting and dieback of infected plants. Chlorosis, etiolation, and slow thinning of the turf doesn't fit the description of this disease. Therefore, what we are seeing now is NOT bacterial wilt.

We've had countless calls and samples over the last week from superintendents who fear they have bacterial wilt because they are seeing chlorotic or yellow turf. It's important to realize that many things can cause turf to turn yellow, and that if you aren't seeing the etiolation and gradual thinning then you probably don't have this suspected bacterial problem. For more information about some of the most common reasons for yellowing turf, please refer to this post on turfdiseases.org.

Several of the samples that came into our clinic this week turned out to be yellow spot. This disease causes chlorotic spots and patches on creeping bentgrass putting greens, but does not cause an abnormal growth habit and we've never seen it lead to thinning of the turf.

Yellow spot symptoms are especially prevalent during dry and hot weather. That certainly fits the conditions we're experiencing in North Carolina right now. For more information about yellow spot, please refer to this Golf Course Management article from the November 2006 issue.

Avid Receives 24(c) Label for Nematode Control in NC

2011-06-23T09:08:00.000-07:00

Golf course superintendents in North Carolina have a new option for nematode control on putting greens.

Avid (abamectin) has been granted a 24(c) Special Local Need label for control of sting and ring nematodes on golf course putting greens. The supplemental label can be downloaded here. It is important to emphasize that this 24(c) label applies only to the Avid brand, is only valid in North Carolina, and only allows for application to golf course putting greens.

The application rate is 57 ounces per acre, with a recommended 3 to 4 applications on a 14 to 21 day interval. Tank-mixing with a non-ionic surfactant is recommended to improve penetration into the root zone, and applications should be watered-in immediately with 0.1" of irrigation.

Suspected Bacterial Disease of Creeping Bentgrass

2011-06-16T19:31:00.000-07:00

Over the last two weeks, the Turf Diagnostics Lab at NC State received several samples of a suspected bacterial disease on bentgrass putting greens. All of the affected golf courses have been in the Piedmont region, from Raleigh to Greensboro to Charlotte.

Most locations are reporting yellowing and etiolation of the bentgrass followed by a slow thinning. The symptoms are relatively mild in these locations. Two courses experienced a more rapid and widespread decline. In all cases, the symptoms are limited to areas that were severely damaged last year by heat stress or other diseases.

We are working to isolate and identify the bacteria associated with these samples. Since there are bacteria in almost every turf sample we receive, we need to determine if the bacteria are pathogenic before we can be sure that they are the cause of the problem.

In the meantime, golf course superintendents who are seeing these symptoms are advised to avoid abrasive practices like aerification, verticutting, and topdressing. If the symptoms are localized to cleanup passes or certain greens, then dedicate a mower to those areas or wash the mower thoroughly and spray it with a 10% bleach solution before moving to other greens. Mowing affected areas last after the dew has dried or spraying with a hydrogen peroxide solution before mowing may also help to minimize the spread of bacteria.

In addition, anything that can be done to minimize stress on the turf is advised; for example raising mowing heights, switching to solid rollers, or skipping mowings on affected areas.

We are investing all of our effort and resources into determining the cause of this problem and developing a practical solution. We have initiated trials at 4 golf courses to evaluate practices that may help to control it. Be sure to follow our blog or sign up for email alerts to receive regular updates:

Like us on Facebook: facebook.com/turfpathology

Follow us on Twitter: twitter.com/ncturfpathology

Receive alerts by email: feeds.feedburner.com/turfpathology

Program '11 Update: More Dollar Spot and Brown Patch

2011-06-03T12:48:00.000-07:00

Dollar spot pressure has continued to be very high, and brown patch exploded over the last week as well. For our Program '11 treatment, we proceeded as planned on May 23 with an application of 26GT (4 fl oz) + Fore (6 oz). We also made the scheduled application of Terrazole (4 oz, watered-in) to clean up any Pythium root rot activity that may have been triggered by recent wet weather.

The changes that we made to Program '11 have done a good job of getting the dollar spot under control. In fact, Program '11 is the only treatment that is clean of dollar spot this week. All of the other programs contain noticeable amounts of the disease.

All of the programs are providing excellent brown patch control.

Turf quality is still mostly being impacted by dollar spot. Only Program '11 and the Bayer Program are providing acceptable (>5) turf quality, with Program '11 providing significantly greater quality than all other treatments.

For more information about our Program '11 Project, or to follow along on Facebook or Twitter, please visit our website turfpathology.org.

Type I fairy rings in warm-season grasses

2011-06-03T08:00:00.000-07:00

Type I fairy ring symptoms on a bermudagrass fairway

This spring we've seen a tremendous amount of Type I fairy ring on bermudagrass fairways and landscapes established with zoysiagrass and centipedegrass. Type I fairy ring symptoms are the most severe, causing decline or death of the affected turf. In most cases these symptoms appeared as soon as the turf began to green-up in the spring. The affected turf never greened-up, indicating that it had been killed over the winter.

Note how the symptoms stop near the drainage basin

How and why did this happen? I suspect that these rings began to develop last year during periods of wet weather in the spring. In fact, some people noted that these same areas had green (Type II) fairy ring symptoms last year. All of this fungal growth may have turned the soil hydrophobic, or water-repellent, and caused the turf to be killed by winter desiccation. Or maybe the extra nitrogen released into the soil profile by the fairy ring fungi caused the turf to be more prone to winter injury.

Either way, the important thing now is to take steps to encourage a rapid recovery. Wetting agents or soil surfactants should be used to re-wet the soil in affected areas, and spiking or aerification should be done to break up the mat of dead turf. Avoid application of DNA herbicides, like prodiamine, as these inhibit root growth and will slow recovery. Fungicides probably won't help to speed up the recovery, but they may help to prevent the problem from recurring next year. For a list of fungicides labeled for fairy ring control, please visit the Disease Management Utility on TurfFiles.

For more information on fairy ring, check out our fairy ring disease profile.

Brown Patch Alert

2011-06-01T04:32:00.000-07:00

Brown patch has exploded on tall fescue landscapes and creeping bentgrass putting greens over the last week in the Piedmont of North Carolina. Warm night temperatures, high humidity, and rain have created ideal conditions for this disease to develop.

Looking at the weather forecast, conditions will remain favorable for brown patch for the foreseeable future. Creeping bentgrass putting greens and high-value tall fescue landscapes should be treated with preventive fungicides as soon as possible. If the disease is allowed to progress much longer, recovery will be very slow now that the summer heat has set in.

The QoI fungicides azoxystrobin (Heritage), fluoxastrobin (Disarm), pyraclostrobin (Insignia), and trifloxystrobin (Compass) are best for brown patch control and provide 21 to 28 days of protection against the disease. None of these products are readily available to homeowners, and the products you'll find on the shelves at home improvement stores are not very effective against brown patch. If you have a brown patch problem in your lawn or landscape, it's best to call a professional.

For more information about brown patch, please visit turfpathology.org.

Program '11 Update: Dollar spot and Pythium root rot

2011-05-19T06:00:00.000-07:00

We're only two months into our Program '11 Project and are already seeing major differences among the fungicide programs we're evaluating. Here's an update on things:

We've already made a number of changes to the Program '11 treatment because of the continuing cool and wet conditions. Dollar spot pressure has been very high for the last month, and frequent rainfalls have increased the risk for Pythium root rot development. Here are the changes we've made so far:

We were scheduled for a Bayleton application on April 4 for fairy ring prevention, but the soil temperatures were too cool. Instead, we moved-up the application of Honor originally scheduled for April 11 because the weather was very favorable for Pythium root dysfunction and dollar spot.
The Bayleton treatment for fairy ring was applied on April 18 when 5-day average soil temperatures finally reached 55F.
Due to an outbreak of dollar spot in the Program '11 plots, we made an emergency application of Daconil + Torque on April 29. Therefore, we cancelled the application of Torque that was originally scheduled for May 2.
Instead of applying Signature + Banol on May 9, we decided to go with Banol + 26GT on May 12 due to continuing dollar spot pressure and wet conditions favorable for Pythium root rot.

Now to the results:

Clemson's Program 13, which hasn't received any fungicide treatments yet, is getting hammered by dollar spot as you would expect
The NC State Program has also failed to provide acceptable control of dollar spot. This is probably due to the intense dollar spot pressure this spring combined with the watering-in of most treatments for fairy ring and PRD.
The Bayer, Syngenta, BASF, and Program '11 treatments are providing good to excellent dollar spot control.

Turf quality is primarily being affected by dollar spot, so the treatments that are providing good dollar spot control are exhibiting the best turf quality right now. The Bayer and Program '11 treatments have the highest turf quality because they are providing the best dollar spot control. Program 13 and the NC State Program are not providing acceptable turf quality at this point.

For more information about our Program '11 Project, or to follow along on Facebook or Twitter, please visit our website turfpathology.org.

Program '11 Project: Here are the programs

2011-05-10T21:19:00.000-07:00

As part of the Program '11 Project, we will be evaluating several popular fungicide programs for creeping bentgrass greens, and comparing them to a program that we developed for our specific location (NC State Program) and another program that is modified based on this year's weather conditions (Program '11).

You can find all of the details of each program by following the links below:

1. Program 13 from Clemson

6. Program '11

We'll be providing regular updates during the season on the performance of these programs and how we've adjusted Program '11 based on this year's weather conditions.

For more information about our Program '11 Project, or to follow along on Facebook or Twitter, please visit our website turfpathology.org.

Program '11: An example fungicide program

2011-05-04T11:29:00.000-07:00

Following the steps I outlined in my last post, we developed a fungicide program for an 'A-1' creeping bentgrass putting green built to USGA specifications in 2005.

Located on our Lake Wheeler Turf Field Lab, this green has a history of Pythium root dysfunction and fairy ring problems, and we were also hit with Pythium root rot last year during an extended period of wet weather. Dollar spot, brown patch, and algae are also problems on this green as they are on most bentgrass greens.

We used an excel spreadsheet to assist with developing the program. The diseases we need to control were listed at the top, with each column across the sheet corresponding to a week during the growing season. Using our knowledge of the weather conditions that trigger each disease and historical weather data from the State Climate Office of North Carolina, we highlighted the weeks that each disease is likely to be active. This gives you a good visual image of what diseases need to be controlled with each fungicide application. We used the Disease Management Utility on Turffiles to select a fungicide or tank-mixture that would control the diseases that are expected to be active during each week. We tried to avoid having to make fungicide applications on back-to-back weeks, but in several cases we needed to do that because application methods (foliar vs. watered-in) were not compatible.

Here's the program we came up with:

March 14: Segway (0.9 fl oz, watered-in)

April 4: Bayleton (1 fl oz, watered-in)

April 11: Honor (1.1 oz, watered-in)

May 2: Torque (0.6 fl oz, watered-in)

May 9: Signature + Banol (4 oz + 2 fl oz)

May 23: 26GT + Fore (4 fl oz + 6 oz)

May 30: Terrazole (4 oz, watered-in)

June 6: Disarm C (5 fl oz)

June 13: Subdue Maxx (1 fl oz, watered-in)

June 20: Honor + Fore (1.1 oz + 6 oz)

July 5: Signature + Daconil Ultrex (4 oz + 3.2 oz)

July 11: Segway (0.9 fl oz, watered-in)

July 18: Disarm C (5 fl oz)

Aug 1: Stellar + Daconil Ultrex (1.2 fl oz + 3.2 oz)

Aug 15: Spectro + Alude (5.76 oz + 6 fl oz)

Aug 29: Subdue Maxx + Fore (1 fl oz + 6 oz)

Sept 12: Reserve (3.2 fl oz)

Sept 26: 26GT + Daconil Ultrex (4 fl oz + 3.2 oz)

If this seems like a lot of applications and an expensive program, you're absolutely right. Several of these applications are specifically to control Pythium root rot, which can develop any time between May and October in North Carolina depending on when the wet weather comes. This is why adjusting your fungicide program based on the current conditions is so important - many of these Pythium applications could be avoided if the weather is dry and unfavorable for Pythium root rot development at that time.

This year we'll be comparing this NC State program to other common fungicide programs, and one that we adjust on the fly based on the current weather conditions, to see which method provides the best disease control and highest turf quality.

For more information about our Program '11 Project, or to follow along on Facebook or Twitter, please visit our website turfpathology.org.

Speeding the recovery from spring dead spot

2011-04-19T06:30:00.000-07:00

From what I've seen and heard, spring dead spot is particularly severe this year, which isn't a surprise given the cold winter with alternating wet and dry periods. These types of conditions are ideal for spring dead spot.

Unfortunately, there is nothing you can do in the spring to control spring dead spot. The pathogen does its damage in the fall and early winter, which causes the turf to be more susceptible to freezing injury. Even though you see the symptoms now, the disease isn't actively developing at this time.

The best you can do is to take steps to speed the bermudagrass recovery from the spring dead spot symptoms. Recovery from spring dead spot occurs primarily through the spread of stolons into the patch from the outside. There are several ways this can be accelerated:

1. Avoid use of DNA herbicides, like prodiamine, for pre-emergence control of crabgrass and other annual grasses. These herbicides inhibit turf root growth and will prevent the bermudagrass stolons from rooting as they spread into the patch from the outside. Oxadiazon is recommended instead because it does not inhibit root growth.

2. Break up the layer of dead turf in the spring dead spot patches through spiking or hollow-tine aerification. Roots emerging from the bermudagrass stolons cannot penetrate through this layer of dead turf to reach the soil below. Just like a grow-in situation, you need to establish good stolon-soil contact.

3. Apply fertilizer and irrigation in light and frequent doses, again mimicking a grow-in situation, to encourage growth of the poorly-rooted stolons. Note that the total amount of fertilization should not be increased, as any excess residual nitrogen remaining in the fall could exacerbate the disease.

For more information about spring dead spot, please see our spring dead spot disease profile.

Program '11: Develop a fungicide program in 4 easy steps

2011-04-15T06:00:00.000-07:00

Designing a fungicide program for golf course putting greens is a daunting task, even for the most experienced golf course superintendent. There are many factors to consider, and at times it seems too many products to choose from. However, I think it becomes a lot easier if you break it down into 4 easy steps:

Which diseases do I need to prevent? It should seem obvious that developing a good fungicide program is impossible without first answering this question. You need to know which diseases you're trying to control in order to design a good program! Yet, it is not uncommon for superintendents to skip this step or get it wrong. For example, I see a lot of superintendents throughout NC spraying unnecessarily for take-all patch, which is only a problem at high elevations in the western part of the state. On the other hand, a lot of people with older bentgrass varieties like Pencross, Pennlinks, Dominant, Crenshaw, and L-93 do not treat their greens for anthracnose, which is a common problem on these varieties.
What weather conditions trigger development of these diseases? Now that you've selected the diseases you need to control, it's time to become familiar with the conditions that trigger their development. Each disease develops under a specific set of conditions, whether it be a range in soil temperatures, night temperatures above a certain threshold, or other factors. These conditions, to the best of our knowledge, are explained in detail in our disease profiles. Take the time to become familiar with the diseases you need to control and what conditions favor their development.
When can I expect these diseases to be active in my location? Weather conditions vary widely across a state like North Carolina, so it's not possible for us to develop a blanket recommendation for application timing that everyone can follow. Fortunately, the State Climate Office of North Carolina has 30-year average climate data for a number of weather stations across the state, which are easily accessible on their website. Using this historical weather data, you can pinpoint the approximate date on which diseases will tend to become active. For example, looking at the historical data from Raleigh, night temperatures tend to rise above 50F on May 1. For root diseases, use average daily air temperature to estimate soil temperature. For example, average air temperatures reach 55F on about April 7, so this would be the time to start preventing fairy ring.
Which product or products will control all of the diseases I need to prevent? This is still the hard part, but we've made it a lot easier by answering the first three questions. For every week during the growing season, we know which diseases are expected to be actively developing in the turf. Now all you need to do is work through the season, and for every week make sure that you are protected against those diseases. For this, you need an information source that ranks fungicides based on their effectiveness. The Disease Management Utility on TurfFiles was developed just for this purpose. This online decision aid allows you to select up to 5 diseases and it will return a list of fungicides ranked in order of their average effectiveness against the diseases you selected. Detailed information on each fungicide, including trade names, formulations, application rates, application intervals, and specific application instructions are also available on this system.

If you work your way through these steps, you should come out with a really solid program for your putting greens. Of course, every year is different, and it is important to adjust a program during the season as necessary, again using the conditions that favor your diseases as a guide. Next week, we'll take a look at the fungicide program that we developed using this system, and through this blog we'll keep you up to date on how we change it through the year. Stay tuned in one of the following ways!

Visit our website! turfpathology.org/pages/program11.aspx

Like us on Facebook: facebook.com/turfpathology

Follow us on Twitter: twitter.com/ncturfpathology

RSS Feed for Email or Google Reader: feeds.feedburner.com/turfpathology

Spring rings on MiniVerde greens

2011-04-12T10:15:00.000-07:00

We don't have a whole lot of MiniVerde in North Carolina yet, but we've had several reports of widespread rings appearing on MiniVerde greens as they are greening up this spring. Interestingly, we haven't had similar reports from superintendents with Champion or Tifeagle greens.

The rings on MiniVerde are typically about 1 foot in diameter and are very irregular in shape, not perfectly circular. The turf on the outer edge has a yellow or reddish-brown cast to it.

Any time we see this type of spring symptom on warm-season grasses, we automatically think that it is large patch caused by Rhizoctonia solani. Based on our initial look at samples, it is definitely a Rhizoctonia disease, but we are isolating to confirm exactly which species is the culprit.

Either way, recovery should be very quick once sunlight and warm temperatures come and the bermudagrass starts growing aggressively. In fact, two superintendents reported that the symptoms have already become less noticeable as the bermudagrass continued to green up.

A fungicide application probably isn't necessary, but could help to speed up the recovery process if the symptoms are very severe or widespread. Any systemic Rhizoctonia fungicide, such as azoxystrobin, flutolanil, or fluoxastrobin should provide good control. Check out the Disease Management Utility for a complete list of products labeled for large patch control.