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Poa Annua Seed Head Control at Des Moines Golf & Country Club

March 22, 2012

This article comes to us from Rick Tegtmeier, CGCS, Des Moines Golf & Country Club.

At DMGCC, we are like many other golf courses in Iowa, we have poa annua and we try to control the ugly seed heads that emerge in the spring. Many different types of growth retardants are used and we are no different. We use a combination of Primo and Proxy to control our seed heads. When we spray it on our fairways we use the following rates of PGR: Primo at 5 oz per acre (.11 oz/1000) and Proxy at 220 oz per acre (5 oz/1000). This is commonly referred to as the 5 and 5 program.

One thing we all struggle with is to when we start spraying the turf. In the case of poa annua seed heads, control must be done well ahead of the emergence of the seed head from the sheath area of the plant. We have found that using a Growing Degree Calculator has been our best tool to get the timing correct on when we do our first spray. I use a simple Excel spreadsheet to enter my daily temperatures and it automatically figures the cumulative total of Growing Degree Days.

My good friend Steve Cook, CGCS, MG,Director of Agronomy at Oakland Hills Country Club wrote an explanation on Growing Degree Days for his membership and I have included a little bit of that here. One thing to note is to make sure you know what model (base) of GDD calculator you are using. We use the 32 degree base at DMGCC and some people use the 50 degree base. Just make sure your cumulative days match your model!

Here is Steve’s explanation of GDD and how it affects the plant:
The growth rates of many biological organisms are determined by temperature. As temperatures increase, activity increases. One of the ways we measure the biological activity of plants and insects is Growing Degree Days or GDD. Knowing the GDD allows us to monitor a specific number and apply plant protectants (like insecticides) at the appropriate time in an organism’s life cycle to maximize control. It has applications for plants like crabgrass or poa annua as well. What is GDD and how is it calculated? We assume that an organisms growth rate increases as the temperature rises above a predetermined base temperature. Each organism may be given a specific base temperature. Knowing these activity thresholds is important and we monitor them depending on our target pest and optimal treatments.

This year the timing is much earlier than we normally spray. We do 2 sprays in the spring to control those pesky seed heads. There are some studies out there that advise you when to make the second application as well. This too is based on cumulative GDD’s. Until more work is done though, we will continue our program of spraying 21 days after the 1st spray. We typically apply some ferrous sulfate with the 2nd spray to mask some of the PGR effects. If you would like a copy of our Excel Spreadsheet shoot me an email and I would be happy to share it with you.

Rick Tegtmeier, CGCS
Des Moines Golf & Country Club


The Organic Golf Course

August 18, 2010

Here is an article that was recently published in the New York Times about the Vineyard Golf Club located in Edgartown on Martha’s Vineyard.  The golf course opened for play in 2002 and was only allowed to be built under the provision that the facility would operate without the use of any synthetically produced products.  The club is thought to be the only completely organic golf course in the United States. 

Jeff Carlson, course Superintendent, talks about the creative methods he uses to manage the course and how to tries to promote the idea of playability over visual perfection.  Carlson admits that a higher budget is needed and that their practices might not work as well in other parts of the country. 

It’s definitely an interesting read and makes you stop and think.  But do you think articles like this help or hurt Superintendents and the Golf Industry?  While I think most would agree that moving towards a sustainable approach is a step in the right direction, this article focuses on one course in a particularly unique environment.  Will the general masses who read this article understand that environmental conditions play such an important role in managing diseases?  Or after reading this article will they expect their local course to abandon their current practices and adopt new ones?

Your thoughts?    

Exclusive Golf Course is Organic, So Weeds Get In

Standing alongside the 13th green at the Vineyard Golf Club on Martha’s Vineyard, Jeff Carlson spotted a small broadleaf weed between his feet. As the superintendent charged with maintaining the club grounds, he instinctively bent to pluck it, then stopped.  Click Here to read the rest of the article. 


Weeds at the Hong Kong Golf Club

September 29, 2010

Recently I have been getting e-mails from friends and family back in Iowa telling me about all the weed pressure this season from the wet weather conditions. Their messages got me thinking about some of the weeds around here in Hong Kong and I thought it would be interesting to share about three different types of weeds that are an ongoing battle for us here at the Hong Kong Golf Club.

Goosgrass Eleusine indica
Goosegrass is a summer annual grass, which grows as a perennial here in our subtropical climate. Goosegrass pressure is intense on nearly all parts of the course and grows very well in compacted and high traffic areas. Recently, a pre-emergent herbicide plan has been implemented using Barricade and we have had great success. By using this pre-emerge program in the fairways, roughs and all other major play areas, we have saved a massive number of man-hours that were devoted to hand pulling weeds. We still have a crew of who spends a majority of their day walking the fairways with a weed removing tool and a trash bag trying to control the Goosegrass. At the end of the day most of the managers have filled up the back of their carts from pulling Goosegrass on their courses whenever they see a troublesome clump trying to take over.

Water Hyacinth Eichhornia crassipes
Water Hyacinth is a water dwelling weed that is incredibly invasive and can destroy the make up of a pond or lake. It quickly covers the entire top of a body of water, cutting out sunlight to lower levels, and sucks all the oxygen out. There was an article in the August edition of Golf Course Management (pg 40) about a new insect that they believe will help control populations of Water Hyacinth. Unfortunately, the insect is just being released in Florida and I do not know if it will ever be made useful here in South East Asia. Our current control method is again, manual removal. Every few months our landscape team will go in and remove all the Water Hyacinth from this pond. Unfortunately, if you leave just one leaf, it will be completely covered again. We are keeping our fingers crossed it does not invade other ponds on the course.

“Creeper” Mikania micrantha
Chinese Creeper, or more commonly known just as “Creeper” is a weed that has most of Hong Kong in its grips, literally. Creeper is a perennial weed that quickly grows and overtakes trees and all other vegetation. It smothers them from the light and eventually kills them. This vine can be seen taking over forests in the mountains and if anything sits for too long, creeper will eventually overtake it. Our arboriculture team regularly removes the vine from our tree lines here at the golf course. They do a great job keeping it from overtaking our natural areas, but it is a never-ending job. There are some chemical controls for it, but it is easiest and safest to just remove by hand and to try and keep populations at a minimum so it doesn’t get out of control.

Damian Richardson
Hong Kong Golf Club


Annual Bluegrass: Friend or Foe?

May 23, 2011

Frenemy – a blend of the words “friend” and “enemy” that refers to an ally who is simultaneously a rival. An example of such would be Dwight Schrute and Jim Halpert in The Office, or two teammates fiercely competing for a starting spot. In a turfgrass sense, Poa annua and I are frenemies.

Here in the Midwest, Poa is an enemy: a weed with poor roots and annoying seedheads. However, it provides an unmatched playing surface in a temperate climate. In fact, you can even be Poa annua’s friend on Facebook.

My golf and turf management background has mainly been in Iowa, so I’ve become familiar with the differences in appearance, playability, and management of an entirely bentgrass green and a heavily Poa infested green in this region. The winter annual tolerates stress just enough to be a problem, but it can't withstand the conditions bentgrass can.  Therefore, it remains a weed.

Turf managers and golfers have a much different experience in a climate that Poa is better suited in. I’ll never forget my first time playing on an entirely Poa green in Northern California. The turf was so finely textured it was difficult to see individual leaf blades. In addition, the greens rolled incredibly fast yet surprisingly true.

That experience led me back to the Pacific Coast for a summer internship where I gained a new perspective of Poa. I was amazed to see the greens mowed at less than 0.09 inches, aggressively verticut biweekly, dried out for weekend play, and yet the turf bounced back quickly. If Poa was improved to tolerate adverse conditions and could be utilized on golf courses everywhere, superintendents would no longer need to fight it as a weed. This may be possible considering the plant's great ability to adapt.

Dr. Don White at the University Minnesota has research reports on Poa annua dating back to 1985 and has a breeding program there. Dr. David Huff at Penn State University has also been breeding annual bluegrass since 1994. Even so, a uniform supply with traits that increase stress tolerance is still not available.

Breeders have a difficult task in commercially producing annual bluegrass. Seeds are difficult to harvest because Poa annua has a plastic phenotype (one that can change). The desirable grass plant at low mowing heights produces an undesirable seed when the plant grows tall enough to be harvested. Propagating the grass from seed may not be realistic for another reason: Poa established from seed often sprouts seedheads at green height, which requires growth regulator to inhibit them from forming. Vegetative propagation of the turf is also difficult.

Imagine for a minute that Poa has successfully been bred to be used commercially for golf course greens. The limited rooting depth issue could possibly be alleviated with a shallower rootzone, allowing the water table to perch with less irrigation. This and other cultural practices can only be researched and implemented if Poa can be commercially produced. Somewhere down the line, genetic resistance to Anthracnose or tolerance to cold and heat may even be developed.

Superintendents will be managing Poa this year, but they will still be treating it as a weed. There is, however, validation in breeding it. Most people consider annual bluegrass an enemy. I, on the other hand, have an optimistic view of the plant.  This leaves Poa annua and I as frenemies.



"Creeping Charlie" (Glechoma hederacea) control

October 22, 2013

Ground Ivy, or “Creeping Charlie” is probably the most difficult perennial broadleaf weed to control in Iowa. It is an excellent indicator of compacted and poorly drained soils. Ground ivy reproduces by seed and also by rooting on its creeping stems. It was first introduced to the United States as a ground cover alternative in shaded areas. However, its extensive runners (up to 5-10 ft. long) not only began out-competing lawn grasses in the shade, but it quick spread rapidly into full sun.


Ground Ivy is easy to identify with its distinct square and prostrating stems, which readily root at the nodes (as seen to the right from the Scotts grass manual).  The leaves are round to kidney-shaped; borne on a short petiole.  When crushed or mowed the leaves give off an aromatic minty odor.  This aromatic odor often characterizes the Lamiaceae or “mint family” and contains many household cooking spices such as basil, rosemary, and peppermint. Ground Ivy has bright green leaves on an opposite leaf arrangement. The bluish-purple, trumpet-shaped flowers usually appear in May. 


The best time to treat ground ivy with postemergence herbicides is when it is translocating carbohydrates deep underground in the late fall and maybe even as late/after the first frost. The late fall application will not yield visible results until the spring. Repeated applications and persistence over multiple seasons may be required for complete control. Even with complete control there is a strong possibility it will move back in rapidly from a surrounding area. A combination of postemergence herbicides containing 2,4-D, dicamba, MCPP and triclopyr provides the best potential control. Below you will find a few additional pictures.


Unusual September Weeds and Diseases in Iowa

September 24, 2013

With last week’s abnormally warm September weather, several diseases and weeds were discovered around the state of Iowa. Brown patch thrived with night temperatures above 70F⁰ coupled with high humidity. Brown patch is caused by the fungal organism Rhizoctonia solani. Damage affects the leaf blade from the tip down and is usually noticed in grasses which receive high amounts of nitrogen fertilization. Symptoms are straw colored irregularly shaped foliar lesions with a brown boarder. R. Solani can attack most cool-season grasses, but is most commonly noticed on creeping bentgrass greens, tall fescue lawns and Kentucky bluegrass.

Symptoms on bentgrass putting greens appear as a copper/gray-colored “smoke rings” ranging from a few inches to several feet where mycelium can be seen. Figure 1 below was taken last week by Dan Strey at the ISU research station. Figure 2 is from University of Missouri Extension IPM: Identification and management of turfgrass disease - looking at leaf and sheath lesions of brown patch.  


Figure 1: Brown Patch at ISU research station
Figure 2: University of Missouri publication looking at tall fescue foliar syptoms of brown patch


There are many fungicides that provide brown patch control such as Daconil, Banner Maxx, Heritage, and several others. Cultural practices such as reducing nitrogen levels and preventing long periods of wet conditions can reduce disease pressure. With temperatures tapering off over the weekend, hopefully it will be the end to the high temperature summer diseases in Iowa.

Oddly enough, in the middle of September we have also seen crabgrass and goosegrass seedlings germinating at the ISU research farm. Normal crabgrass germination occurs in mid-April to mid-May depending on your location in the state. Crabgrass is easily identified with fine hairs on the leaves and sheaths as well as its distinctive “protruding fingers” seedheads. Crabgrass also has a rolled vernation, while goosegrass has a folder vernation. 

Goosegrass is often mistaken for crabgrass and some people incorrectly refer to it as “silver crabgrass” because if it’s silvery appearance of the lower sheaths.  Goosegrass generally germinates 2-3 weeks later than crabgrass in the spring. The seed stalks of goosegrass also appear somewhat like a zipper with two individual seeds protruding in two directions. In figure 3 and 4 below you will see the side by side comparison from the Scotts grass manual.

Figure 3 and 4: Goosegrass and Crabgrass comparison from Scotts grass manual

Goosegrass is very difficult to control, even with the use of preemergence herbicides. The best postemergence option is a nonselective herbicide such as glyphosate. Optimal crabgrass postemergence control is obtained when applied while the crabgrass is small and actively growing. The use of fenoxyprop, quinclorac, and dithiopyr are the best options.



Name That Patch – Early Spring Brown Spots

March 28, 2011

Parts of the Midwest are getting hit with another round of snow but there is no denying that spring continues to inch closer by the day. In fact, before this last blast of winter weather, spring activities were slowly getting underway. Trees were beginning to break dormancy, bulbs were peaking through the soil, and lawns were starting to green up.

This process has already started across parts of the Midwest and some of you may have noticed patches, or areas of brown in your lawn. It’s typical to receive a number of questions from your clients about the cause of these brown spots during spring green-up. There are a number of reasons why these patches can appear and this article will address some of the most common reasons and discuss what action, if any, is needed to remedy the situation.

Dormant warm-season grasses
Most lawns in the upper Midwest contain cool-season grasses like Kentucky bluegrass, perennial ryegrass, and tall and fine fescues. Occasionally lawns, or parts of the lawn, will contain warm-season grass species. Examples of these could include zoysiagrass, buffalograss, or nimblewill. Whereas cool-season grasses grow best in the spring and fall, warm-season grasses prefer the mid-summer months and will remain dormant (brown) longer into the spring until warmer temperatures arrive.

If zoysiagrass or buffalograss are the cause of your brown spot there isn’t much you can do other than exercise patience until warmer weather arrives. Nimblewill can be selectively controlled with Tenacity herbicide. Tenacity herbicide will be made available to homeowners later this spring. Consult a lawn care professional for more information about Tenacity herbicide.

Dormant patches of nimblewill are very noticeable early in the spring.  Nimblewill can be selectively controlled with Tenacity herbicide.  Consult with a lawn care professional about the availability and use of Tenacity herbicide.


Warm-season grasses such as buffalograss are still brown while cool-season grasses such a fine fescues begin to green-up.

Leftover annual grassy weeds
Annual weeds such as crabgrass are always a concern and last year they seemed to be particularly troublesome. In lawns that had severe outbreaks, some of these annual grassy weeds may still be present. The good news is that you don’t have to worry about controlling leftover annual weeds. They have completed their lifecycle and are no longer alive. They did however drop seed and you may consider using a pre-emergence herbicide for the upcoming season.


Goosegrass, an annual grassy weed, is still present from the previous growing season. 

Snow molds
Damage from pink and gray snow mold is most evident shortly after the snow melts. The grass will usually appear off-color and be matted down. Chemical applications to control snow molds in the spring are seldom recommended as most of the damage has already taken place. You can help your lawn by raking up the matted areas of grass with a leaf rake. Chances are there is some live turf hiding underneath. The picture below shows an area of gray snow mold on the Iowa State University central campus.


Gray snow mold on the Iowa State University campus. 

Dog spots
Damage from animal urine will definitely create brown spots in the lawn. Where you can usually count on some recovery from snow mold damage, dog spots are very effective at killing grass. The best course of action is to remove the dead grass, break up the soil with a hand trowel or rake and re-seed the area. Note: Seed will not germinate and grow if a pre-emergence herbicide is to be used. The exception to this rule is when Tenacity or Siduron herbicides are used. Consult with a lawn care professional for more information about these products.


Man's best friend.  Undoubtedly charming, but damaging to grasses.

Salt damage
De-icing materials that contain sodium can be quite harmful to turf. Brown patches or areas of turf along driveways, sidewalks, or streets could be caused from salt damage. Depending on the severity of damage, reseeding may be necessary. Aerification and watering (or rainfall) can help flush salts through the soil profile and improve the conditions of the site.

Marcus Jones
Graduate Research Assistant

Nick Dunlap
Undergraduate Research Assistant


BROWN AREAS IN YOUR LAWN? IT COULD BE Rough bluegrass (Poa trivialis)

July 26, 2018

Rough bluegrass, or Rough Stalk bluegrass, Poa trivialis is closely related to Kentucky bluegrass (Poa pratensis).  There are some important differences, however.  Rough bluegrass is common in Iowa lawns.  It is a source of many calls at this time of year, because it tends to turn brown more quickly than the Kentucky bluegrass in times of heat and drought.

It forms patches of a light green, dense turf in the spring and fall when there is enough moisture.  It is best adapted to wet shaded conditions and may be included in seed mixtures for that environment.  Unfortunately, it often grows out into full sun areas.    It is very intolerant of heat and drought and turns brown in dry summers.   It is not dead, but dormant and will recover quickly when it cools down and there is more moisture.

Kentucky bluegrass has underground stems called rhizomes, whereas Rough bluegrass has stolons.  It has a boat shaped leaf tip and a folded vernation like the Kentucky. 

It is often mistaken for a disease problem in Kentucky bluegrass.  One needs to look at it closely to see the stolons.

Slide shows stolons (above ground stems) of Rough bluegrass.  Picture from American Society of Agronomy (ASA) turf slide set.



It has a boat shaped leaf tip and folded vernation, like Kentucky bluegrass.  It's membranous ligule varies from short to quite pronounced.  In this picture, the ligule is short.



It sheath is like the middle picture, split part of the way down, whereas Kentucky bluegrass is split all the way to the node.  (ASA slide set)



Lower sheaths may take on an onion-skin like appearance.  (ASA slide set)



In spring it appears as light green patches in the turf.  (Taken from web, source Dr. Zac Reicher)



In hot dry weather it may turn reddish or a light purple color and then turns brown.


There is no selective control for it in Kentucky bluegrass.  You either need to live with the brown spots in summer, or wait until it recovers, kill it with glyphosate (Roundup) and seed back into the dead spots with Kentucky bluegrass.  Roundup will not kill it when it is dormant.  Sufficient irrigation in midsummer may also prevent it from going dormant.


Weed Control in Home Lawns

March 7, 2014

The complete elimination of weeds in the lawn is not a practical goal for many homeowners. A more realistic approach is to minimize weed populations through various control measures. An attractive, well-maintained lawn is an important component of a home landscape. Unfortunately, an infestation of weeds can reduce the aesthetic quality and vigor of the turf.

Today's blog is a revised Iowa State University extension publication on Weed Control in Home Lawns. The publication focuses on cultural, mechanical, and chemical practices that can be used to control weeds. Weed control of sedges, broadleafs, annuals, and perennials are highlighted below. In addition, you will find a comprehensive list of pre/post emergence options in the market today as well as a table on postemergence herbicide effectiveness.

The entire extension publication is attached in pdf form. To download the publication, click on the following link Weed Control in Home Lawns.

or the following address: