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.

It's Back! Large Patch that is ...

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.

Large Patch Symptoms on St. Augustinegrass

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 root pruning 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.

Treat for Large Patch Now!

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 Temperatures as of 9/18/12 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 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.

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

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.

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.

Type I fairy rings in warm-season grasses

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.

How's the spring dead spot?

This is probably the most common question I get this time of year as everyone anxiously waits to see how much disease there will be this year or if their preventive fungicide applications worked. Based on our winter weather conditions, with cold temperatures combined with periods of wet and dry weather, I expect the disease to be pretty severe this year and early reports seem to indicate that it's going to be a bad year. We've even had a report of a severe outbreak of the disease on zoysiagrass fairways.

Unfortunately, my travel is limited this time of year due to classes and conferences, so let me ask you: How's the spring dead spot out there? Any particular successes or failures with fungicides? Please post a comment to let us know what you're seeing!