Return of the Fungi!

Things have been relatively quiet here at the NC State Turf Diagnostics Lab with regards to disease samples, however that has changed in the past couple of weeks now that warm-season turfgrasses are starting to fully wake up from their winter nap. So, without boring you to death with blah blah this and blah blah that ... here's the rundown.

Warm-Season Turf (Bermuda/Zoysia/Centipede)

Many samples have been submitted both digitally and physically to the clinic over the past few weeks that have shown winter damage. The majority of these samples were taken from shady, wet, and/or north facing slopes. These are typical areas we expect to see this type of damage on warm-season turfgrasses. In most cases, it appears that green up has been delayed and no complete turf losses have been reported. The exception to that has been centipedegrass. We have seen some centipede lawns that we can't find any disease, insect, nematode, soil problem, etc. where winter kill is strongly suspected. This is all unfolding as I type this, so we may see cases of other warm season turfs with winter kill as they continue to fully green up across the state. For more information about winter injury in North Carolina, please read Dr. Grady Miller's recent post by clicking here.

From a disease standpoint, the most common diagnosis in the past week or so has been spring dead spot on bermudagrass. This has been documented on common, hybrid, and ultradwarf types. Given the fact that spring dead spot is highly correlated with cold injury, it is no surprise that there is a lot of spring dead spot damage out there this year in North Carolina. There is nothing you can do from a fungicide standpoint at this time to recover from this disease because the damage was done last fall. For more information about spring dead spot, please click here.

Spring dead spot symptoms on ultradwarf bermudagrass

Spring dead spot symptoms on hybrid bermudagrass

Typical winter kill symptoms on warm season turf

Cool-Season Turf (Bentgrass & Ryegrass)

As expected, we haven't seen many cool-season turf samples in the past few weeks since they are able to withstand the ravages of fungi for the most part in the spring and fall.

One exception has been red leaf spot, caused by the fungus Drechslera erythrospila, on creeping bentgrass putting greens. This is a disease we have observed over the past several years. For the most part, it has been fairly random and isolated, however we are starting to see more and more of this disease for whatever reason. If you think you have red leaf spot, now is the time to treat. None of the samples that have come into the clinic are producing spores yet. This tells us that while the fungus is waking up and starting to infect via mycelium spread, it hasn't reached it's full potential to produce abundant spores. Once spores are produced, the damage will be more widespread and rapid. For more information about red leaf spot, click here.

Red leaf spot symptoms on a creeping bentgrass putting green

Finally, we have observed some dollar spot damage on perennial ryegrass in over seeded situations. Recent weather patterns have been favorable for this fungus to start coming out and eating away at our precious stands of perfect turf, so beware! If you haven't started your preventative dollar spot programs, now's the time ... especially on high value turf like creeping bentgrass. For more information about dollar spot, click here.

Dollar spot symptoms on perennial ryegrass

What's Happening Now?

RECENT CREEPING BENTGRASS PROBLEMS

Over the past several weeks, we have received many creeping bentgrass putting green samples.  In every case, samples were submitted to check for a disease and in EACH case absolutely no pathogen activity was discovered.  Therefore, our diagnosis was "a disease was not responsible for the damage".  The common thread has been the combination of core aerification and topdressing with the unusually arid weather for this time of year. When the putting surfaces are opened up after aerification, they are more susceptible to drought stress, especially if the humidity is very low. This effect is exacerbated in areas that are already stressed such as clean up laps, heavy on/off traffic spots, etc.

This is a fine example of why receiving a diagnosis of "no disease" is just as important as receiving a diagnosis of an actual disease. Because symptoms developed during excellent growing conditions for creeping bentgrass, a safe assumption is a disease is responsible for the damage.  Yet, in this case an accurate diagnosis can save time and money by preventing unwarranted fungicide applications.  If you don't agree, feel free to make a fungicide application for drought stress and see what happens.

Typical Stress Symptoms Observed with Recent Samples

TREAT FOR LARGE PATCH NOW!

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

Average Daily Soil Temperatures as of 10/01/13 via 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 severe damage from 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.

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.

For more information about Large Patch, including images and specific control recommendations, click here.


TREAT FOR SPRING DEAD SPOT NOW

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.

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.

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

What Disease?

If I had a wooden nickel for every time someone has said the following to me in the past few weeks, I'd be able to build a raging fire ... "I bet you are swamped with samples in the clinic right now with all the rain we've had, etc. etc., etc." Actually, outside of a few oddball cases, we haven't seen or heard of any major disease problems on creeping bentgrass putting greens. The missing link has been heat stress. If we look back at our records, some of our busiest years have been those that were hotter and drier which ultimately leads to more stress on the plant therefore making them weaker and more susceptible to infection by pathogens.

One of the oddball cases we have diagnosed in the past couple weeks has been summer patch on creeping bentgrass putting greens. The symptoms of summer patch appear as circular patches or rings, ranging from 6 inches to 3 feet in diameter. Turf within these patches initially turns off-colored, is prone to wilt, grows poorly, and may appear sunken in the turf stand. Over a period of a few weeks, the turf continues to decline, turns yellow or straw brown and eventually collapses to the soil surface. The outer edges of the patch are usually orange or bronze when the disease is actively developing. The patches recur in the same spot annually, and can expand at a rate of 2 to 4 inches per year.

Summer patch symptoms on creeping bentgrass

The summer patch fungus attacks the roots, stolons, and rhizomes in the spring when soil temperatures reach 65°F. Summer patch symptoms are rarely seen during the early stages of disease development, instead, the symptoms appear in mid-summer after considerable damage has been done to the root system. Heat, drought stress, and nutrient deficiencies are the main factors that encourage the expression of summer patch symptoms. In North Carolina, the symptoms typically appear in early to mid-July.

For more information about summer patch, including control recommendations, click here.

Finally, if any of you are wondering about Pythium root rot, we have only diagnosed a handful of cases thus far with all of those happening within the past 7-10 days. In every case, we have found the Pythium to be active in the upper thatch layer around roots closest to the plant. With that being said, if you are treating for Pythium root rot, don't water those fungicides in TOO much. We typically recommend about an 1/8" ... which in most cases equals about 3-4 minutes with part circle heads. Either way, you may want to take the time to see just how long it takes to put that amount out.

Pythium root rot following drainage route

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

Guess What? Pythium LOVES Water!

If you've learned nothing else about turfgrass diseases, fungi love water and while not technically a fungus, the oomycete Pythium absolutely adores water. Now, you're sitting there thinking "boy, it sure has been wet lately across much of North Carolina, especially in western NC, and instead of reading this blog post, I should be firing up my sprayer and putting out something to prevent Pythium diseases." Well, if that's not the thought you had ... you better switch gears and make it happen.

Rainfall Estimates for Last 30 Days

For those of you managing bermudagrass putting greens or if you're trying to grow in a freshly seeded stand of anything, you better be on the look out for Pythium blight. We have diagnosed Pythium blight on 'Champion', 'Mini Verde', and 'Tifeagle' bermudagrass putting greens over the past couple of weeks. They are not bullet proof folks! We've also seen a lot of yellow patch on the ultradwarfs, but we'll save that for another day.

For those of you managing creeping bentgrass putting greens, you better be starting up your Pythium root rot prevention program. Two of the biggest misconceptions associated with Pythium and creeping bentgrass is that Pythium blight is common on putting green heights and Pythium root rot only occurs during the hot days of summer. Both are false. We rarely see Pythium blight on creeping bentgrass at putting green heights, especially if it's a well established mature stand. We have diagnosed Pythium root rot on creeping bentgrass putting greens in North Carolina in every month except the winter time.

For more information about Pythium blight and root rot, including control recommendations, visit the links below.

Pythium Blight

Pythium Root Rot

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 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

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

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

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

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'

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

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

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

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.

Suspected Bacterial Disease of Creeping Bentgrass

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:

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Program '11 Update: More Dollar Spot and Brown Patch

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.

Brown Patch Alert

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

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:

1. 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.
2. The Bayleton treatment for fairy ring was applied on April 18 when 5-day average soil temperatures finally reached 55F.
3. 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.
4. 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

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

2. BASF Program

3. Bayer Program

4. Syngenta Program

5. NC State Program

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

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.

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

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:

1. 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.
2. 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.
3. 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.
4. 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!

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