I’ve had a few questions this summer about bacterial etiolation and decline in bentgrass putting greens. I routinely check for this disease but have not observed it this year in any samples submitted to KSU so far.
A few days on Twitter I saw an excellent update from Dr. Rick Latin (Purdue University) about this disease. You can click HERE to read it.
(Megan Kennelly, KSU Plant Pathology)
“Dutch elm disease -is that still out there?”
“Elm trees – are there any of those still out there?”
Those are two questions, flip sides of the same coin, that I hear every year. The answer to both is YES.
Judy O’Mara, Director of our Diagnostic Clinic, handles most of the tree samples and she has picked up DED in several samples this summer, like we do every summer. Sanitation (removing and destroying infected trees) is essential to DED management. If infected trees are near other elms, root grafts need to be disrupted first. For nitty-gritty details on DED you can visit this page – click HERE.
Here is a photo of the DED spore-producing structures in the dissecting microscope.
Dutch elm disease is caused by this fungus (actually two related fungi) which is spread by elm bark beetles. In the photo above, we see the black stalks and a creamy, gooey ball of spores at the top. The beetles pick up the spores and move them around from tree to tree. The fungus can also spread tree-to-tree in neighboring trees by root grafts.
Initial symptoms are “flagging” of individual branches, especially when the disease was introduced by the beetles. The disease spreads over weeks or months through the rest of the crown.
(Photo courtesy Ray Ladd, K-State Research and Extension)
Branches wilt, but leaves remain on the tree. Disease can develop more quickly when triggered by root graft method of spread. Discoloration in the vascular tissue can be seen by stripping off the bark of recently-wilted branches:
For high value elms, preventative fungicide injections (appropriately-labeled products of propiconazole or thiabendazole) are an option to reduce the risk of Dutch Elm Disease (though it is not a 100% guarantee). This can be one piece of the DED management system. Remember, sanitation is a key piece of reducing the risk of DED (See the link above). Here is a photo of the big elm at the K-State Garden.
This tree is on a 3-year injection cycle. We thank Matt Giese from Syngenta for providing some Arbotect fungicide to inject this tree, and we thank Randy James, Consulting Arborist from Tree Biologics, for generously donating his time to inject the tree a few weeks ago. We use our injection days to educate students, Extension Master Gardeners, and others about DED.
This yucky summer weather just keeps going. The past few days have been the most humid I have experienced in a while. Hot and humid = Pythium weather. We’ve mentioned foliar Pythium a few other times during this stressful summer of 2016. (As a reminder, foliar Pythium is distinct from root Pythium… which we’ve also discussed a few times!)
In the past we days we received a couple of samples of Pythium foliar blight (also called Pythium cottony blight). One was from a perennial ryegrass golf course fairway.
In the photo above you can see the greasy, matted down appearance of the turf. With a handlens, or even just with the naked eye if you looked closely, mycelium was present. In the microscope it was clearly Pythium (see the tall fescue pics below).
Here are some shots of the ryegrass in the field:
The second sample was from a tall fescue home lawn. Usually we think about Pythium on ryegrass or creeping bentgrass, but it can attack other cool-season turfgrasses. Tall fescue has more potential to recover than perennial rye or bentgrass. In 11 years, I have seen it on tall fescue only 1 or 2 two times before.
Below is a photo of the greasy, matted-down tall fescue turf. After incubating overnight in a plastic box with wet paper towel the mycelium was present.
In the microscope, the pathogen was clearly distinguishable as Pythium.
Just as a comparison, check out the strong crosswalls that are found in the brown patch pathogen, Rhizoctonia solani:
Here is a shot of the site, where it looks like the Pythium was tracked along with a mower:
The pattern is different from brown patch, and brown patch lesions were not present. I have seen weird tracking patterns with fertilizer burn or other chemical injuries, too. It can be challenging to know what is what. If you have any doubt, send in a sample, and email some photos.
Pythium thrives in wet conditions, so avoid overwatering. Water deeply and infrequently, and avoid watering in the evening. Improve drainage and try to increase airflow and sunlight. Avoid overfertilizing – Pythium loves an overly lush lawn. As a bonus, those practices will also reduce the risk of brown patch.
Pythium is not a true fungus, it is an oomycete. The most effective fungicides for Pythium are the ones specifically for oomycetes. There is a comprehensive list here, from the Chemical Control of Turfgrass Diseases publication from University of Kentucky (click the photo to zoom in):
There is some more excellent information, photos, and management tips here:
http://extension.missouri.edu/p/IPM1029-17#Pythiumfoliarblight
Brown patch is still active out there (it’s a little faint in the pic, but it’s there):
And dollar spot is active, too (mixed in with more brown patch):
(By Jared Hoyle; KSU Turfgrass Research and Extension)
It’s getting close to that time of year again – to start promoting available scholarship opportunities through the Heart of America GCSA. Please help spread the word to your students (when school starts in August). Deadline is October 31, 2016.
SCHOLARSHIP OPPORTUNITY – 2016
The Heart of America GCSA Scholarship Program offers educational aid to deserving students in the turfgrass program at an accredited college or university in Kansas or Missouri.
A total up to $5,000 is allocated each year to deserving students. Applicants will compete based on their overall qualifications determined by the Scholarship and Research Committee.
Applicants:
2016 academic term
(Must carry a 2.75GPA or higher for consideration.)
Application:
Scholarship Application – 2016 – PDF File
Scholarship Application – 2016 – Word File
Deadline:
October 31, 2016
Submit to:
Heart of America GCSA
Scholarship & Research Committee
638 W. 39th Street, Kansas City, MO 64111
Questions:
Kim Weitzel; kweitzel@westerneda.com
(By Jared Hoyle: KSU Turfgrass Research and Extension)
Every year we create new turfgrass research reports. This year we have lots of new information from the release of a new zoysiagrass to unmanned aircraft systems for drought monitoring.
Listed below is a list of topics and links to the 2016 reports. Enjoy!
(By Jared Hoyle; KSU Turfgrass Research and Extension)
Do you have an unwanted weed or a disease that you can’t figure out what it is or how to control it? Check out the Lawn Problem Solver at the KSU Turfgrass Website. Is has information about how to identify those pesky weeds, diseases, insects and more.
Bob Vavrek explains how the hot humid weather finally has made life miserable for maintaining cool-season turfgrass putting greens. There are options out there to help out your putting greens but you always want to make sure to minimize injury to the turf during these stressful times.
Check out the article on the USGA website here.
http://www.usga.org/course-care/regional-updates/central-region/the-turf-trifecta.html
(Megan Kennelly, KSU Plant Pathology)
I am not great with sports metaphors, but I’m going to give this a chance. I was looking at declining roots in the microscope and thought…
Growing bentgrass putting greens in Kansas in summer is like coaching an athlete riding the Tour de France.
Actually, it’s even harder because instead of a mere 21 day grind it can be a 3-month grind.
In my story here, you are the coach, the turf is the athlete, and the rootzone/soil is the bicycle.
Maybe you are lucky and have a high budget “bike” for your athlete. The bike (the rootzone) was well-built, top-of-the-line, with excellent construction, drainage, excellent sand, etc. The biker (the turf) undoubtedly will still have to work hard, especially in the “mountain stages” (those weeks with high humidity, high temperatures of 100 and lows of 81). But at least the bike itself (the soil) is not going to add to the challenge and make it any harder than it needs to be.
Maybe you are less lucky, though, and what you have for your athlete is this, a Huffy beach cruiser:
It’s what your sponsors are able to provide for your athlete. When your turf is not riding the Tour de France, like when it is growing from September through May, this bike works okay. It gets the job done. However, when the going gets tough (June, July, August), it is VERY tough. It is VERY VERY VERY tough in the mountain stages. The bike is slow and clunky. The turf is already stressed, and the bike just makes it worse.
What can you do?
Like a coach training an athlete for the Tour de France, preparing your grass for summer is a year-round commitment. Build the best bike you can. That is, build the best soil profile you can. Aerify and verticut in the fall. Reduce shade and improve air flow. Get on a regular topdressing program.
Your athlete needs food, too, not just a bike. Green photosynthetic tissue = food. Raise the mowing height a tiny bit, or roll instead of mowing, or skip mowing now and then. Don’t just do this in summer – consider doing this in spring/fall when the grass is growing. Put down adequate N in the fall, and spoon-feed during summer. Your athlete can’t ride up the mountain if it is starving.
Explain to your sponsors (your golfers/members) that if your budget is a Huffy beach cruiser, they can’t expect that same as with a high budget piece of equipment. Maybe they can increase the budget, and at least get a moderately prized bike (pay for some extra aerification in the fall, buy some equipment to do some needle-tining in summer). Maybe they don’t even know it’s a Huffy, and with some explanation, you can get permission to rebuild some problematic greens. Dig up some cores, show it to them, and talk about drainage, root health, oxygen, etc. Communication is critical.
If the athlete is showing signs of stress, get help right away.
I know this metaphor was a little clumsy – if you made it to the finish, congratulations!
By Dr. Raymond Cloyd
Have you noticed that your geraniums and petunias are not blooming (flowering)? Well, the “critter” or culprit causing the problem may be the caterpillar or larval stage of the tobacco budworm (Heliothis virescens).
Click “continue reading” to learn more:
Or click HERE if the above “read on” link does not work.
Our own Dr. Jack Fry is an expert on cool-season turfgrass physiology. He co-wrote a book on the topic:
and he developed an online GCSAA class (click HERE) as well.
So, every year, around this time, I end up asking him about mid-summer turfgrass decline. I asked Jack to write some thoughts for this blog:
In the midst of a summer with 100+ F temperatures, it’s worthwhile to consider some of creeping bentgrass’s preferences and management strategies that might be helpful to reduce its stress, and yours. See, the thing about creeping bentgrass on putting greens is….
| Average July maximum temperature (°F) | Average July minimum temperature (°F) | |
| London, England | 72 | 55 |
| Manhattan, Kansas | 90 | 68 |
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