Friday, July 29, 2011
July 29, 2011
This is a follow up to my post of July 26 on leaf spot damage. By the way, I added a picture of my own lawn at the end of that post. Those of you with leaf spot in turf are not alone.
Yesterday, the 28th, I was asked to look at some lawns in the Polk City and West Des Moines area. What I saw was a lot more leaf sport damage.
On the lawns below, the entire subdivision had been irrigated during the early summer. Just before the heat, the irrigation system went down for a few days. We are just coming off of nearly two weeks above 90F. Some days reached 99 and 100. This is ideal conditions for leaf spot to develop. Even lawns that had irrigation in surrounding areas showed a lot of damage.
At this site, there was a clear pattern. It was the areas exposed to the sun, particularly south facing slopes that showed the greatest damage. This is very severe damage, but it will recover. Typical of leaf spot, the older leaves have died, but the new growth appears to be healthy. I recommended that they fertilize about the 15th of August and I predict that most of it will recover by October.
This is a south facing slope, and it shows some of the worst damage.
This is a very interesting picture. The foreground is a south facing slope. The background, which is on the same irrigation system and received the same treatments and mowing as the lawn in the foreground shows very little damage. The difference is that the background is a north facing slope that was protected from afternoon sun by the houses and by the slope.
Should you apply fungicides at this time? Damage is already done and recovery is beginning to take place. I don't think that fungicides would be worth the cost at this point.
This was a convergence of just the right conditions for this disease to occur. Hopefully we will not see damage this bad again for a few years.
Thursday, July 28, 2011
Summer seeding: During this talk, some of the ideas about seeding rates and timing were discussed to give turf managers more tools when deciding when to seed, for what purpose, and how much to seed during different times. The philosophy and science behind traditional seeding rates and higher than normal rates were discussed and a demonstration was in place to show what different seeding rates look like as well as ways to determine how much seed you are putting out without properly calibrated equipment. Lastly, we discussed how higher than normal seeding rates can reduce herbicide inputs by outcompeting weeds.
If you ever need to determine how much seed you have put out, there is a simple rule you can follow. If you are sticking to normal seeding rates (1.5 lbs/1000 ft2 for KBG; 8 lbs/1000 ft2 for PR and TF), you can always pick out a 1 square inch area and could how many seeds you see. You should count somewhere around 16 seeds in a square inch for either of the seeding rates listed above.
Higher than normal seeding rates are necessary when we introduce cleated traffic to a turf stand. We don’t hesitate to recommend turf managers putting out an initial rate of at least 20 lbs/1000 ft2 when starting from bare ground to get as much wear tolerant biomass established as possible before traffic starts. This method of seeding at higher rates can also result in an essentially weed free stand of grass, especially with a quickly establishing grass like perennial ryegrass.
Moss & Algae control: Dr. Minner gave a good overview of the different types of moss and algae that can inhabit bentgrass putting greens, or anywhere conditions are right for their growth and development (wet, low mowing height, high N). He also showed preliminary results of a study that uses different methods and chemicals to control silvery thread moss on greens. Two products, MossBuster, and QuickSilver herbicide (carfentrazone), which has labeled rates and instructions for silvery thread moss control, are being evaluated both in combination with each other and on their own at different rates to determine the most effective control of silvery thread moss.
The main problem with the MossBuster product is that it can have an extremely phytotoxic effect on bentgrass, however, it is extremely effective in killing silvery thread moss. Conversely, QuickSilver is effective, but not as effective as MossBuster at finishing off moss populations. So far, a low rate of MossBuster combined with a low rate of QuickSilver, applied frequently (1 week apart), has shown the least phytotoxicity and the moss control is on par with higher rates of each product in combination or on its own. This study is still relatively new and we will continue to monitor the effects of each treatment.
Apps for turf managers: Dr. Marcus Jones has been watching the turfgrass technology front very closely over the past few years and was able to give attendees a short discussion on a relatively new ‘App’. The iStimp is an app that claims to act as a stimp meter on golf greens and is available for Apple devices including the iPod touch, iPhone, and iPad.
Essentially, you set the ball in the small divot of the ‘home’ button on the iPhone, set it on the ground, and lift up until the ball starts to roll. Once the ball has rolled its distance, you use a built in ruler to measure the distance. The phone then calculates what the reading would be on a regular stimp meter. Dr. Jones is working on a research project that will test the effectiveness of this app when compared to the traditional stimp meter. Keep tuned to the iaTURF blog for updates on this project.
GPS spraying: GPS based technology has been around the agriculture field for a few years now and it’s slowly starting to creep its way in to the turf industry. We were fortunate to have a few of the current models on the market present at field day this year. We also saw a demonstration of how the technology works; the sprayer can minimize drift, minimize overlap, steer itself, calculate exact rates of application, and many other things. It’s truly an amazing technology and it probably won’t be long before everyone has some sort of experience with one of these machines.
If anyone has any questions or comments about Field Day 2011, please feel free to contact me, Andrew Hoiberg (firstname.lastname@example.org) or any of the other speakers. This truly was one of the best field days I’ve been a part of and we owe it to a great turfgrass industry in Iowa. Thanks to the vendors and attendees for a wonderful day! We’ll see you next year!
Iowa State University
Wednesday, July 27, 2011
Iowa Turfgrass Field Day has returned! Everyone associated with this event are thrilled to have it back and we know the turf industry is as well. We would like to thank everyone who pitched in to help, all the speakers, the vendors, and most of all, the attendees. Without a great industry like we have in Iowa, none of this would be possible.
Below you will find a recap for the first half of the program and some take home messages from the research and demonstrations that were highlighted at this year’s event. A recap for the second half of the program will follow tomorrow.
NCERA Bentgrass Trial: Dr. Christians showed us the NCR Bentgrass variety trial that aims to maintain bentgrass with limited fungicide inputs and to test different cultivars natural resistance to disease pressure, namely dollar spot and brown patch. The trial has 24 cultivars of commercially available creeping bentgrass. This trial is still underway but there are cultivars that are standing out. “Declaration” is cultivar that others are measured against for natural disease resistance.
Biostimulant Study: Quincy Law, a recent graduate of the ISU turf program, filled us in on his Ajinomoto study. The objective of this study was to determine the effect of an amino acid based fertilizer upon growth and shoot density of "Penncross" creeping bentgrass. Previous work with an amino acid containing product, GreenNcrease, had resulted in higher shoot densities when applied to mature turf. Treatment applications of three natural products at varying rates, along with urea, were made every two weeks to fairway height turf (0.5 inches). Color, dry clipping weight, dollar spot ratings, total nitrogen analysis of clipping tissue, and shoot densities were all recorded monthly.
Plots receiving applications of GreenNcrease, an Ajinomoto product, had significantly higher shoot densities. GreenNcrease applied as a biostimulant along with a regular fertility regime may increase shoot density. An increased shoot density provides for a more competitive turf stand and better playing surface. The trial completed in 2010 is being repeated on the same plots to investigate the effect of these products when used over time.
Imprelis update: As many of you know, Imprelis herbicide has been in the news a great deal this year as it is suspected of causing damage to White Pine and Norway Spruce trees. It appears as though the herbicide could be moving downward into the soil and being absorbed by mature root systems that extend well beyond the traditional drip line cutoff for spraying. If you have had problems with Imprelis, it is recommended that you contact DuPont. Dr. Christians also spoke about an Imprelis trial examining the efficacy of the herbicide on grassy and broadleaf weeds when applied at various timings in the spring/early summer. The results of this trial will be available this fall. Also, stay tuned for further updates concerning Imprelis as more information becomes available.
Nitrogen based establishment: This trial is attempting use increased rates of nitrogen during establishment of both Kentucky bluegrass and perennial ryegrass hasten the production of aboveground plant mass and improve the wear tolerance during traffic stress. So far, we have been able to detect differences in nitrogen rates as far as fill in and plant maturity, especially when compared to the untreated controls. From what we have seen thus far, it looks like applying 0.25 lbs N/1000 ft2 per week for 8 weeks of establishment for a total of 2 lbs of N produced the most aesthetically pleasing perennial ryegrass with regard to color and density. Incremental increases beyond 0.25 lb N per week caused ryegrass to grow excessively, which could potentially increase mowing requirements.
For Kentucky bluegrass, more nitrogen is necessary to achieve a dense stand that can withstand traffic. We have also had to use 4 applications of Tenacity herbicide at 4 oz/A spread throughout the spring and summer to keep weeds at bay and give the bluegrass a chance to establish enough for cleated traffic. It appears that at least 0.5 lbs N/1000 ft2 per week for 8 weeks during establishment is necessary to achieve maximum density. However, as we continue to collect data on this study, we may find out that rates of 0.75 or even 1.0 lbs N/1000 ft2 per week are best for rapidly establishing bluegrass.
Iowa State University
Tuesday, July 26, 2011
July 26, 2011
Yesterday, July 25, I began to notice a lot of damaged grass around campus and around Ames. This was not unexpected because of the extreme weather that we have had lately. We are nearing records for days over 90 F, followed by 70+ F nights with sufficient moisture to keep the turf green. This is ideal conditions for several diseases.
The problem appears to be Leaf Spot caused by the fungal organism (Drechslera poae). The old genus name for this organism was Helmintosporium, a name that still in use by much of the industry. This disease is common at this time of year, particularly when the spring has been wet.
So, if you have this problem, what should you do. There are a number of fungicides labeled for this disease, but usually we let it run its course. The area should recover later in the season and through the fall. Notice in the last picture that the new leaves are emerging in a healthy condition. I am expecting full recovery by September.
The first three pictures below shows leaf spot on central campus at Iowa State. It has now gone into the crown and root stage and the damage is quite apparent.
Damage just outside of Horticulture Building.
Beardshear hall just off of central campus.
Individual leaf showing lesions.
It is typical of this disease to damage older tissue first. Notice that the newly emerging leaves are health.
Here is an additional picture that I took yesterday afternoon on my own lawn.
In the area where afternoon shade cools the Kentucky bluegrass, there is very little leaf spot. In the area that gets the stress from the afternoon sun, there is considerable damage from leaf spot.
Friday, July 22, 2011
July 22, 2011
The two most asked questions of the week are 1) how long will Imprelis persist in the soil and 2) will Imprelis damaged trees recover.
The answers are:
1. Imprelis is known to be quite persistent in soil, but how long it will last depends on a variety of factors. These include rainfall, soil type, organic matter content of the soil, temperature conditions through fall and spring and other variables that will be different from region to region. As a result, there is no clear answer to that question. I would expect that most of the material applied this spring at label rate will be gone by next season, but again, it will vary by location and conditions on the site.
2. The answer to question 2 is also going to vary. At this point, no one knows for sure what is going to happen next year.
There are already companies coming up with questionable solutions. See
Here is my best guess on what is going to happen. It will depend of the extent of the damage.
The tree below has damage limited to 2011 new growth. I'm betting that it will recover next year, but of course I will not know for sure until next spring or summer.
The tree in the next picture is border line. If it recovers, I will be surprised.
This one, which is located on the same course in Chicago as the other two, is likely dead and will show no recovery next year.
The only thing you can do at this time is get good photographic record of the damage and wait until next year to see what recovers.
Monday, July 18, 2011
|Adult Japanese beetles burrowing into a golf course putting green.|
The number of adult Japanese beetles has exploded the last couple of weeks. Once confined to the northeastern region of the country, this destructive insect has become a permanent part of the Midwestern landscape. This pest has continued its trek west across the country since being introduced into the U.S. from the Orient. Japanese beeltes were first reported in Iowa in 1994 and have gone on to inhabit approximately half of the counties in the state.
The Japanese beetle is one of the white grubs that includes the May and June beetle, masked chafer, green June beetle, European chafer, Asiatic garden beetle, Oriental beetle, and black turfgrass ataenius. The adult beetles can be identified by their green and bronze metallic head and shell and by the white tufts of hair that run along their abdomen. The larval stage must be identified by their raster pattern.
As with all white grubs, the Japanese Beetle larvae feed on the roots of grass plants just below the soil surface. Injury first often appears as drought that fails to respond favorably to irrigation. Each year the adult beetles emerge from the soil and begin mating and laying their eggs. This is the period we are currently experiencing. The eggs hatch in 2-3 weeks and the larvae begin feeding. Feeding can continue through the fall up until the first frost. Injury can also occur in the spring but is usually less severe due to the vigorous growth of cool-season grasses.
This particular grub species is somewhat unique in that the adult beetles also are significant pests of a wide range of ornamental plants. Japanese beetles feeding on leaf tissue leave a skeleton framework of veins following damage. Damage typically occurs at the top of the tree and works downward. Below is a picture of a Linden tree that is under attack from Japanese beetles.
|Adult Japanese beetles feeding on a Linden tree. The beetles usually start feeding at the top of the tree and work their way down.|
Monitoring for white grubs can give you an indication of the severity of damage you may be able to expect. Sites with heavy beetle infestation in the summer months are likely incur grub damage during the fall months. Also, be sure to watch areas that have been damaged in the past as grubs often reinfest the same areas.
There are a number of insecticides on the market that are effective at controlling white grub species. The key to effective control is proper timing and placement of the products. Products applied preventatively or curatively are more effective against the grubs when they are small.
Regardless of the timing of the application, it is essential that the product be effectively watered in. Using nozzles that produce larger droplet sizes will help place the product further down in the canopy. Irrigation is normally recommended to help move the product down below the thatch layer and into the soil where the product will be most effective.
Based on the number of adults we are seeing we could be set for significant damage this fall. Monitoring for adult beetle activity is a great tool for those of who haven’t treated and are trying to decide what to do. The margin for error appears as if it will be quite slim as the turf will already be experience summer decline as we move through a week with high environmental stress.
Let us know what you’re seeing out there.
Friday, July 15, 2011
Turf managers have curiously watched and anxiously waited for technology currently used in agriculture to be scaled down for utilization in turf. GPS and auto steer on tractors, combines, and sprayers have allowed farmers to navigate fields for better coverage in less time, perform site-specific management, accurately monitor yield, increase spray efficiency, reduce fuel consumption, and even work through the night.
It was only a matter of time. Iowa State Turfgrass researchers have performed a dual demonstration of GPS turf-sprayer technology at the Horticulture Farm. The results of the demonstration will be on display at the Iowa Turfgrass Field Day on July 21, 2011 at the Iowa State University Horticulture Research Station.
The objective of the dual demonstration was to test the accuracy of the GPS sprayers. Two simulated “greens” were outlined in spray paint and glyphosate was applied by two different sprayers within the two painted areas. The premise was easy: kill the grass inside the spray paint. The task, however, was much more difficult.
Steve Willey of Capstan Turf Systems brought out a Toro sprayer outfitted with Capstan's sprayer technology for the trial. Capstan offers three modules of aftermarket technology, and all three were used during the demonstration. Click here to learn more about Capstan and their products.
Van Wall John Deere retrofitted a sprayer for Tim Van Loo of ISU Athletics with GPS technology for use on Iowa State's sports fields. Mr. Van Loo repeated the process for the second part of the demo. Van Wall's website can be accessed here.
Keep in mind the two sprayers used in the demonstration weren't exactly the same and that this was not a head-to-head competition. Reel and rotary mowers work differently, as do these sprayers.
Watch a short video below to see the Capstan sprayer technology in action. The sprayer demonstrations and companies involved in will be in attendance at the Turfgrass Field Day.
ISU Turfgrass Reserach Assistant
Tuesday, July 12, 2011
July 12, 2011
Steve Cook, CGCS, MG - Director of Agronomy
Tuesday, July 12, 2011
Throughout the summer I have been asked numerous questions about this item in particular and the information gathered by its use.
“What does that tool do?”
The basic definition of a soil probe is a tool used to remove a deep core from turf areas to examine root development, thatch depth, soil arrangement and soil moisture.
Some consider checking your soil profile an art form. You have to use your senses of sight, touch, and smell. (Yes even smell; Anaerobic is a term used to describe a soil that is deficient in oxygen; saturated due to poor drainage. Oxygen is imperative for healthy greens by promoting beneficial microbial activity and decomposing organic matter. Insufficient oxygen begins a downward spiral of problems that does not end well. These soils will have a very foul smell associated with them.)
While evaluating your soil probe plug general questions are asked: does the soil form a “ribbon” between the fingers or does it crumble or fall away? This gives us the information of moisture content in the underlying turf - if it ribbons it means it’s holding moisture; if the soil breaks away or crumbles, the turf is dry.
During the summer, soil moisture is the most important aspect of the keeping healthy turf that maintains consistent playability. This is very hard to tell if you don’t look at the underlining soil to identify the amount of water present. The rule is to keep the turf as dry as possible because it is much easier to add water then to take water away. And too much water can lead to higher disease pressure and maybe turf loss.
Soil probes allow the superintendent to keep adequate moisture levels and to allow more efficient watering, better playing conditions, and healthier turf.
Iowa State University
Friday, July 8, 2011
July 8, 2011
The 4th edition of my textbook, Fundamentals of Turfgrass Management was released for sale on June 22, 2011.
This fourth edition has been updated throughout to reflect the latest information and trends in the turfgrass industry. These changes include the following:
§ Updated information on genus and species names of grasses
§ A new chapter on ornamental grasses
§ An expanded section on micronutrients in the fertility chapter
§ A new section on seed production and the purchasing of seed
§ New information on herbicides, insecticides, and fungicides
§ An expanded section on weed species
§ Updated information on sports turf and sports field construction
§ Updated information on golf course construction and managementIt is available directly from Wiley Publications at
as well as a variety of other book companies on the web. It will also be available at the ISU bookstore in a few weeks.
When I arrived to work this morning I was greeted by an outbreak of dollar spot. We had been on the dry side since the last week June but we received 1.33 inches of rain yesterday. The abundant rainfall coupled with the warm overnight temperatures, and high humidity led to conditions that were very conducive for dollar spot. Mycelium was especially abundant in our untreated creeping bentgrass areas.
Below are a few pictures from one of our creeping bentgrass fairway trials. This particular trial has 24 different cultivars of creeping bentgrass. Each plot is split in half and is either untreated or receives applications of Daconil and Emerald.
The objective of the trial is the determine the susceptibility of creeping bentgrass cultivars to dollar spot when maintained under reduced fungicide applications. Applications of the Daconil and Emerald mixture are scheduled based on a threshold of dollar spot severity in a cultivar with a high level of dollar spot resistance. Declaration is the indicator cultivar in this trial.
This picture shows the Declaration plot in one of the replications. The left half of the plot is the treated side and before today had only received one application on June 6. Declaration is a recently developed cultivar of creeping bentgrass that has relatively high resistance to dollar spot compared with other cultivars. Even the untreated side (right side) is holding up fairly well without receiving any fungicide to date.
This next picture shows a Penn A-4 plot. Here the right half of the plot is the treated side. As you can see, there are noticeable differences between cultivars of creeping bentgrass with respect to their disease resistance.
This trial along with many others will be on display during the Iowa Turfgrass Institute/Iowa State University Field Day on July 21. There is still time to register for the event.
Thursday, July 7, 2011
July 7, 2011
Nimblewill (Muhlenbergia schreberi ) is a warm-season perennial grass with a fine texture and a gray-green color. It spreads by stolons and forms a dense matt in cool-season lawns. It has a rolled vernation and a membranous ligule with jagged edges. It looks a little like creepting bentgrass, but it does not have a long membranous ligule that typifies bentgrass and has fine hairs around the collar. It forms a narrow spike-like panicle of seeds, with each seed having a fine awn (hair) at its tip (Figure 1).
It has been nearly impossible to control once it has become established in the lawn. It can be killed by nonselective herbicides, but it is also a good seed producer and it often returns from seed. It is a warm-season species and it looses its chlorophyll in the fall and takes on a bleached, straw-like appearance that makes it stand out in cool-season lawns. It is sometimes referred to as ‘wire grass’ in parts of the Midwest.Tenacity (mesotrione), was released into the lawn care market in the spring of 2011. It had been available for a few years in the sports turf and golf markets. This material can selectively control nimblewill in Kentucky bluegrass turf. It is also labeled for the control of creeping bentgrass in Kentucky bluegrass and for the pre and postemergence control of crabgrass.
The pictures below are from the lawn of our "answer-line" person in the department, Richard Jauron. Richard gets a number of questions on nimblewill control and decided to do a test in his own lawn. These pictures are from the 5th of July, 2011. Richard will continue to update us on his experience with the material throughout the season. The material will turn susceptible weeds snow-white when it is first applied. It does take at least two applications for complete control of nimblewill, and may take more treatments. Remember too that nimblewill is a good seed producer. We will follow this through next season as well and not stop until control is complete.
Figure 1. Seed head of nimblewill with "awns".
Initial effect of tenacity on nimblewill in Richard's lawn. The white color is a typical
response to this herbicide. Richard will repeat apply two weeks after the