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K-State Turf and Landscape Blog

Author: kennelly

Twig girdlers

Posted on by kennelly

This post is from Ward Upham, originally on the KSU Hort News.

twig-girdlers

We are starting to see damage from twig girdlers as evidenced by fallen twigs up to 3 feet long. The beetle Oncideres cingulata is most likely the culprit. Host trees include elm, oak, linden, hackberry, apple, pecan, persimmon, poplar, sour gum, honey locust, dogwood, and some flowering fruit trees. This insect is distributed throughout the eastern United States from New England to Florida and as far west as Kansas and Arizona. Adults are long-horned beetles with a grayish-brown bodies that are stout and cylindrical. The larvae are also cylindrical with small heads and shiny exteriors. Larvae can be up to an inch long and are light brown to brownish-gray.

Girdled twigs often remain on the tree until a strong wind blows them down. Large infestations can result in a high percentage of girdled twigs. Though this may reduce the vigor and appearance of the tree, the overall effect on the tree’s health is not severe. Twigs are unsightlyand do not fall all at once, so clean up is a drawn out process.

This beetle has a one-year life cycle. Late in the growing season, the female deposits eggs in small scars chewed through the bark and then chews a continuous notch around the twig, girdling it. The notch is cut below the site of egg deposition apparently because the larva is unable to complete development in the presence of large amounts of sap. Girdled twigs die and fall to the ground where the eggs hatch.

Girdled twigs look like a beaver has chewed on them, only in miniature. The outside of the twig is smoothly cut, but the center of the twig appears broken. The larvae begin feeding on dead wood inside the twigs the following spring and continue through most of the summer. Pupation takes place inside the feeding cavity. Development is completed during August when the adult emerges to repeat the cycle.

Though adults feed on the bark of host twigs, damage is minimal until the female starts girdling. Chemical control is impractical, so gather and dispose of fallen twigs in the fall or spring to destroy the larvae inside. Often, natural mortality is high because fallen twigs are excessively dry or carry too many larvae per twig.

Peonies may be cut back

Posted on by kennelly

This post is from Ward Upham, originally on the K-State Horticulture Newsletter

peonies-browing_orig

Peonies often look a little bedraggled by this time of year and gardeners may want to cut them back. That will not be a problem with this perennial. Peonies are essentially dormant by this time of the year, even though leaves may still be green. Cut leaves off close to the ground and compost or discard. (Ward Upham)

Gray leaf spot in perennial ryegrass

Posted on by kennelly

(Megan Kennelly, KSU Plant Pathology)

If you manage perennial ryegrass you are probably well aware of the risks of gray leaf spot.I have not seen it, but I just got my first question about it for the year.

In this region the most common time for GLS symptoms to first appear is early to late August. In some years, epidemics can be severe. In other years, there is little to no GLS. The fungus is picky, with 82-90 degrees as its favorite temperature range. The fungus needs wet conditions as well. The fungus requires certain durations of leaf wetness at different temperatures. At that prime window of 82-90 degrees the infection can occur quickly.

Damage in a rye fairway, a few years ago.

gls-cropped

GLS spores in the microscope, a few years back.

spores

For more details and photos you can check out this page for general information:

http://extension.missouri.edu/p/IPM1029-11#Grayleafspot

And, here is some detailed fungicide information (scroll to page 13):

http://www2.ca.uky.edu/agcomm/pubs/ppa/ppa1/ppa1.pdf

 

 

“Reflecting on Turfgrass” : KSU NDVI research featured in Golf Course Management

Posted on by kennelly

(Megan Kennelly, KSU Plant Pathology)

Research by Dr. Dale Bremer and Dr. Steve Keeley along with former students Hyeonju Lee and Kemin Su is featured in Golf Course Management. Check out the article here:

http://gcmdigital.gcsaa.org/i/706647-aug-2016/74

It’s an online e-magazine format and takes a minute to load.

The researchers were studying how NDVI ratings correlate to visual ratings of turfgrass quality. It’s not as simple as you might think! The article at the link above does a nice job summarizing their academic article.

Bacterial etiolation and decline questions

Posted on by kennelly

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.

Dutch Elm Disease

Posted on by kennelly

(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.

DED-synnemata

 

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.

IMG_0400

(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:

DED-streaking-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.Garden-ELM

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.

IMG_20160629_104530738

 

Pythium foliar blight

Posted on by kennelly

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.

FullSizeRender

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:

rye-2016-fr-supers rye-2016-from super rye-2016-from-superintendent rye-2016-from-supers

 

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.

IMG_2711

In the microscope, the pathogen was clearly distinguishable as Pythium.

Pythium-structures-tall-fescue

Just as a comparison, check out the strong crosswalls that are found in the brown patch pathogen, Rhizoctonia solani:

Slide3

Here is a shot of the site, where it looks like the Pythium was tracked along with a mower:

IMG_2744

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):

Kentucky-turf-fungicides-2015-ppa1_Page_17

 

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):

087

And dollar spot is active, too (mixed in with more brown patch):

088

Your turf is trying to bike up a mountain

Posted on by kennelly

(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.

THE PELOTON CLIMBS THE COL DU GALIBIER ON STAGE SEVENTEEN OF THE 2008 TOUR DE FRANCE

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:

huggy-mens

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!

Geraniums and Petunias Beware of the Tobacco Budworm

Posted on by kennelly

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).

Figure2TobaccoBudwormLarva-1iswlrs

 

Click “continue reading” to learn more:

Geraniums and Petunias Beware of the Tobacco Budworm

Or click HERE if the above “read on” link does not work.

 

“Bentgrass Declining? It’s from Western Europe – You Live in Kansas” by Dr. Fry

Posted on by kennelly

Our own Dr. Jack Fry is an expert on cool-season turfgrass physiology. He co-wrote a book on the topic:

book

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….

  • It came from Western Europe. You live in Kansas.
Average July maximum temperature (°F) Average July minimum temperature (°F)
London, England 72 55
Manhattan, Kansas 90 68

 

  • Its roots die first, then its leaves. Keep the roots happy and you’ll have happy bentgrass and happy golfers.
  • Its roots prefer to grow at 55 to 65 °F; root growth slows even as low as 80 °F. This summer, temperatures near the surface of greens have been over 100 °F.
  • Faults with construction, drainage, management practices may produce a quality turf surface for 10 or 11 months of the year. It’s the one or two other months that cause problems.   If you want to avoid bentgrass decline, then start with a good rootzone.
  • Rootzones that hold water are warmer and also have less oxygen for root growth. If you don’t have an ideal rootzone, work to improve it in the fall and spring with aggressive core aerification and topdressing.
  • The benefits of coring are often seen during summer stress. Why are there green polka dots within the brown turf?  Turf in those spots has roots!green_in_aerification_holes
  • Opening the green’s surface with small, solid tines or spikes can help with water infiltration and root growth during midsummer. Don’t overdo it – the turf is under stress.
  • Although superintendents suspect (and often hope) that a disease is causing the problem in mid-summer, over half of the samples that are evaluated in our lab show no disease.
  • In our climate, air movement across the surface of the green is critical for bentgrass health. If your greens are surrounded, let them free!
  • Maximize summer airflow from the south, but also vent to the north (just like opening two windows to get cross flow in your house).
  • Hand watering can be used to address deficiencies in water distribution of the irrigation system, target localized dry spots, and deal with inconsistencies in water retention and drainage in the root zone. It shouldn’t be overdone or underdone- train and use your best help for handwatering.
  • Syringing refers to applying a light mist of water droplets to leaves only, and then relying upon evaporation of that water to help cool the leaf surface. How effective do you think that is on a humid, July day?  Not very, unless you use a fan to encourage evaporation from the leaf!
  • Trees use light for photosynthesis, so does bentgrass. If trees are shading the green, which is getting the light – the tree, or the turf?
  • Cultivars that are more dense get less Poa invasion, and Poa is more likely to die during summer stress than bentgrass. Plant newer, denser cultivars to reduce Poa.( The photo shows Poa checking out in the heat.)poa dying
  • Light applications of nitrogen can be beneficial during heat stress (0.10 lb. N/1,000 sq. ft.)
  • Newer cultivars have been shown to be more heat tolerant than Penncross, but even these will experience decline during prolonged heat.
  • Clean up laps are often the first to show symptoms of stress. Why?  Excessive traffic and wear.  Have you considered a dedicated mower with a slightly higher mowing height for the clean up lap?  Do you skip clean up laps on some days?mow