Heat Wave Forecasted for Next Week

We have seen relatively few disease issues in the TDL the past month or so. Throughout Upper Midwest temperatures have been warm, but we have also been quite dry. However the forecast for next week is very different. Highs for next week will been in the low to mid-ninties, more importantly night time temperatures will exceed 72 for most of next week. I included a 7-day forecast from NBC 15 here in Madison, but areas west and south of us will likely experience even hotter temperatures. I know that doesn't compare with the excruciating heat experienced by those in the Southeast and Central US, but the forecast is significant for the Upper Midwest. Especially considering that many courses have substantial Poa annua populations.

IF YOU haven't done so already, this weekend or early next week is a great time to protect your plants against brown patch and Pythium blight. Environmental conditions next week will be ripe for these two diseases. Moreover, anthracnose, dollar spot, summer patch and leaf spot could also flare up depending on where you are with fungicide applications. I mention leaf spot because we have been dealing with a Bipolaris leaf spot in the Midwest for two or three years that does not respond well to applications of iprodione. This disease also remains active throughout the summer months and has been problematic primarily for older golf courses. The disease tends to be more severe on certain clones of older creeping bentgrass fairways causing a "splotchy" reddish appearance to fairways. It does not manifest into distinct symptom. An image of typical stand symptoms is below.

Last year we initiated a fungicide trial at a course in Wisconsin to investigate chemical control options and found that Heritage TL, Insignia and a tank mixture of Chipco 26GT and Daconil Ultrex suppressed symptoms when compared to the non-treated control. Chipco 26GT by itself did not suppress the symptoms, indicating that Daconil Ultrex was more effective in controlling this disease. Note that I use the word suppress we have not been able to prevent the development of this disease, only suppress the symptoms. Here is the report from last year's trial. This has been a difficult disease to work with because it only seems to affect certain clones. Thus it took some time to figure out how to rate it.

Some other things to consider for next week: limit mowing by alternating mowing and rolling, skip clean-up passes, raise the mowing height and absolutely avoid applications of DMI fungicides to putting greens.

Top Five Diseases of Warm Season Turf at the 2011 GCSAA Education Conference

What's the Biggest Problem for Warm Season Turf?


Dr. Phil talkin' about Diseases on Monday

Last Monday, Phil Harmon, Megan and I got to teach the Management of Diseases of Warm Season Turfgrasses here in Orlando.

It was out third time doing it together and I think each time we’re getting better. I think Bruce Martin from Clemson has stopped checking up on us to make sure that we’re doing the class right, which is good, but we sure do miss the opportunity to put Bruce on the spot! Bruce taught the class previously for >10 years at GCSAA, and it took three of us to replace one of him!

This year we had about 45 students with Florida heavily represented in the group. We had some visitors from Central America and as far away as Australia, but most of the guys came to talk about bermudagrass and bermudagrass diseases in the southeastern U.S.

A survey taken during the class showed the disease issues that superintendents are most concerned with for warm season turf (by # of mentions):
1. Fairy Ring (22)
2. Rhizoctonia zeae aka mini-ring (18)
3. Large Patch (15)
4. Gaeumannomyces Decline (11)
5. Bipolaris Leaf Spot/Melting out (7)

Surprised?

We’ll follow up in the next few weeks on these diseases and what’s the best management strategies for each of them.

Until next week, signing off from the right coast....

Microdochium Diagnosis: It's Magically Delicious!

Playing off of John's previous post about knowing his Lucky Charms, I thought it would be great to highlight some differences between leaf spots and Microdochium patch. We have seen a lot Microdochium patch throughout Wisconsin. Most likely because the weather has been cool and wet. Before we talk about John's Lucky Charms comment, I think we better discuss the symptoms we have seen.

This time of year Microdochium patch symptoms on creeping bentgrass/annual bluegrass swards are typically water-soaked in the center of the patch with the perimeter of the patch exhibiting chlorosis. Patches this time of year typically range from 3 to 12 inches in diameter. The former name of this disease was pink snow mold. This was a bad name because snow is not required for disease development and the patches are not always pink. This is evident in the picture in the upper left corner of this post. The picture demonstrates the water-soaking in the center of the patch surrounded by chlorotic plants. You'll also notice the abundance of mycelium on the leaves, this is typical of Microdochium patch after incubation. Mycelium production can also occur in the field

Microscopic examination of the leaves coated in mycelium will reveal the crescent moon shaped spores. The spores have a prominent middle septation and lack a foot cell typical of Fusarium species. The second picture in this post represents typical Microdochium nivale spores. John, I loved your analogy of Lucky Charms for describing Microdochium spores. After Damon Smith mentioned the analogy to me, I used it to explain Microdochium to my graduate student. The one problem, he's from China and doesn't know what Lucky Charms are!



We also had a few leaf spot samples come through the clinic. We did not have red leaf spot, but the symptoms are fairly different from Microdochium patch. These symptoms are somewhat similar to what John described, irregular patches that have a reddish, brown tint. The samples that came through our clinic were induced by Bipolairs sorokinana most likely. The transition from last week to this week was fairly dramatic. The previous week was warm and this week the temperatures plummeted. Tonight there is a Freeze/Frost warning for Northern Wisconsin and the Upper Peninsula of Michigan. So we quickly transitioned from summer to fall!



The spores of leaf spot fungi are quite different. The spores are humongous compared to Microdochium spores, have a brown tint and have 6 to 10 septations.

Many golf course superintendents are making a fall application of vincozolin and chlorothalonil or iprodione and chlorothalonil to clean up any late season dollar spot and outbreaks of Microdochium patch. These are good combos for Microdochium and should provide good control until snow mold applications are made. Thiophanate-methyl is fairly effective against Microdochium as well.

All Quiet on The Midwestern Front

Sample submission has essentially ceased in Wisconsin. We have had a few samples of basal rot anthracnose, but really nothing else. Dollar spot is still lingering, although we are not seeing new spots develop in our forecasting experiments. The weather has been fantastic for fall aerifications and fall golf in the Midwest. Currently day time temperatures throughout the Midwest range from the low 80's to the low 70's and night time temperatures are ranging from the high 40's to high 50's.

The temperatures are ideal for cool-season grass growth, yet we have been fairly dry especially in Northern Wisconsin. Most of the Midwest did not receive any appreciable rainfall from Sept. 2 to Sept 8.

Dr. Derek Settle of the Chicago District Golf Association did report some Bipolaris leaf spot on a few creeping bentgrass putting greens, but really nothing else. In his weekly update he made an excellent point about this year. Although disease activity was low, it was still a very difficult year. We experienced one of the worst economic downturns since the Great Depression, which forced many golf course superintendents to make difficult budgetary decisions. From what I gathered from Derek's post, it sounded like many golf course superintendents in the Chicagoland area would rather deal with disease issues rather than the budget issues they dealt with this year.

On a completely unrelated note, for those that have gardens at the shop you should check your tomatoes for late blight. Late blight has been reported on tomatoes and potatoes in Illinois and Wisconsin. If you suspect that you have late blight submit a sample to a diagnostic lab and they will provide a recommendation on how to dispose of the plant properly.

Is it fall already? Not quite...

Cooler temperatures across much of the southeast are going to bring a much needed break from summer this week. Most of our summer-time bentgrass diseases, like anthracnose, Pythium root rot, and brown patch, should start to shut down as the bentgrass begins to grow more vigorously.

It's nice to have a little reprieve, but be sure not to let your guard down. These summer diseases can re-activate quickly if temperatures rise again in the coming weeks. The picture to the right of a severe brown patch outbreak was taken in September 2004 after a period of warm, wet weather. Be especially wary during periods of wet weather or when major aerification and/or topdressing practices are planned.

If you've had problems with Pythium root rot this summer, additional fungicide applications are a good idea during wet weather, such as a tropical storm system. If you've had anthracnose problems this summer, a fungicide application just after aerification/topdressing is a good idea as well, as these abrasive practices can cause a flare in anthracnose activity.

Of course, dollar spot should start to become more active as the temperatures cool over the next month. If this disease has been a major problem for you in the past, be sure to start preventive applications soon before symptoms of the disease appear. Once the symptoms appear, dollar spot becomes much more aggressive and difficult to control.

For those with bermudagrass greens, this is the time of year when leaf spot diseases, such as Curvularia and Bipolaris, start to come in. Preventive fungicide applications for these diseases are recommended during wet, cloudy weather or after topdressing applications. Chlorothalonil typically does a good job of keeping these diseases suppressed, but if you are looking for something that lasts longer, iprodione is a good choice.

Most people think of Pythium blight as a hot weather disease, but on bermudagrass greens, most of our problems with this disease are during cool, wet weather in the fall and spring. The image to the right of Pythium blight symptoms was taken on Champion bermudagrass greens last October. In this case, the symptoms appeared very similar to a leaf spot disease, but typical leaf spot fungicides were not controlling it. Once a sample was diagnoses as Pythium blight at our Turf Diagnostics Lab, the problem was easily controlled with an application of mefanoxam (Subdue Maxx).

Soon it will be time to start thinking about controlling large patch and spring dead spot in the warm-season grasses. Stay tuned - this will be the topic of next week's post.