This is a useful reference from Purdue Extension on water that goes into the spray tank. From the guide:

"Water often comprises ninety-five percent (or more) of the spray solution. What affect might it have on product performance? Research clearly shows that the quality of water used for spraying can affect how pesticides perform. Its effect on product efficacy is reflected in the success of your spray operation ...

Time spent addressing the quality of water used in the spray tank can pay big dividends. This publication provides an overview of water quality and related factors known to affect pesticide performance; testing methods and options to improve the quality of the water used are discussed."

I learned of this document when I read Megan Kennelly's post on nozzles and water quality.

This is a fine guide from Breeden, Brosnan, and Vargas at the University of Tennessee: Understanding how turfgrass herbicides work. It's about herbicide active ingredients and the associated mechanism of action class for those herbicides. It's important to know this so herbicide mechanism of action can be rotated. This is something you want to do before a problem develops. From the guide:

"Developing weed management programs utilizing herbicides that employ different mechanisms of action is critical to both preventing and managing herbicide resistant weeds. It is recommended to rotate herbicides that employ different mechanisms of action as often as possible, as well as implementing cultural practices that maximize turf competition and limit weed encroachment."

This guide lists the mechanisms of action and tells you how to do it. One to add to the #TurfReads list and to keep handy as a reference.

Two things today are kind of related to this topic. One is this -- Jim Brosnan mentioned, and showed photographic evidence, that "weed pressure on Oahu never ceases to amaze."

A sea of sedge. Weed pressure on Oahu never ceases to amaze. #weeds #turf pic.twitter.com/QOaNuo3eAG

— Jim Brosnan, Ph.D. (@UTTurfWeeds) September 28, 2015

And I had a conversation with a golf course designer about fine fescue as an infrequently mown rough, in what climates that species can work, and what happens when it is too hot for fine fescue. And I mentioned that one can plant a number of species other than fine fescue in a warmer climate, but the problem becomes one of "how can we find a ball" because there is a lot of energy for growth. Of course there are various techniques turf managers can use to solve that problem, but then the turf will be alive, but thin. It must be if one is going to find a ball in it.

Once there are voids, weeds have an opportunity to grow. Turf managers can solve this problem too, with herbicides, or with manual removal of weeds. But now comes another problem. That is erosion, in locations with substantial rainfall.

Anyway, it must be that the growth of plants (desired species, and weeds) is related to the energy available for the plants to grow. In general the hotter it is, the more energy there will be for weeds, so when one thins a low maintenance rough, the energy for weed growth or invasion is going to be more in a hotter climate than in a cool one. I looked up some data from Japan -- hour by hour data of temperature and global irradiance for 2014 at Sapporo, Tokyo, and Naha. Then I converted the irradiance to photosynthetically active radiation (PAR) using a factor of 2.04.

I looked only at day time, when the sun was above the horizon. And I arbitrarily cut the data to look only at those hours when the temperature was greater than or equal to 20°C. Then I added up all the light, and all the hours. This is a very rough index of how much energy there is for growth, especially for the weeds that will grow when it is hot. And it is a conservative estimate, because the night temperatures influence growth too, and so does the actual temperature. This is just a quick way to note the differences between locations.

At Sapporo in 2014, the cumulative sum of PAR for hours when the temperature was greater than or equal to 20°C was 3,781 mol m^-2. Tokyo has 5,844, and Naha was 9,124. Oahu is considerably warmer than Naha, so it almost certainly would have more PAR than Naha at this cutoff value.

Just looking at the time, how many hours were there for weeds to grow well in these different locations, by looking at how many hours there were with a temperature at or above 20°C? At Sapporo, there were 1,365 of these hours; at Tokyo there were 2,503; and at Naha it was 3,805. Again, locations in Oahu would almost certainly be more than Naha.

That is a real quick estimate of how much energy there is for weeds to grow, or more specifically how the energy is likely to differ in magnitude from location to location.

And one more thing -- in Scotland where a fine fescue rough actually works well, how much energy would there be for weeds? I don't have the exact irradiance data for Scotland, so I won't try to compare it to exact measurements. But I can give some idea of just how much lower the energy is, or how much lower the duration of time would be for weeds to grow rapidly. Huge disclaimer is necessary here, because the species are different, so a C₃ weed like Poa annua might grow relatively rapidly in Dornoch but I am considering more the C₄ weeds like Paspalum dilatatum or Cyperus rotundus.

It still makes an interesting comparison. Of Naha, Tokyo, and Sapporo, Sapporo is by far the coldest. And in the hottest month of the year in Sapporo, the average low temperature is 19.1°C, and the average high temperature is 26.4°C. How about somewhere in Scotland where fine fescue grows well? I picked Leuchars, just north of St. Andrews. In the hottest month of the year in Leuchars, the average low is 10.8°C, and the average high is 19.2°C.

Jim Brosnan's article from last week's Green Section Record is one you will want to add to the reading list, and after reading it, to your reference file. Entitled Golf's Most Common Weed-Control Challenges, Brosnan gives an overview of the particularly problematic weeds and the most current information about their control -- especially for warm-season or transition zone areas.

For more information about weeds, see the University of Tennessee's Turfgrass Weeds site.

These photos from an abandoned golf course in the southern part of the Tohoku region of Japan are fascinating. They show clearly how three different species perform when they are not maintained for 18 months in that climate. From a consideration of the grass performance when abandoned, one can get a good idea of the maintenance requirements for the grass when it is being actively maintained.

These photos are provided courtesy of Mr. Norifumi Yawata, who kindly shared them with me along with some details about this site.

Formerly a creeping bentgrass green, now covered in weeds, but the korai around the green has very few weeds by comparison.

This site, formerly a golf course, has not been maintained for 18 months. One is essentially looking at what happens to 3 species of grass after 2 growing seasons (2013 and 2014) with no maintenance.

The greens were creeping bentgrass. The tees and the collar immediately around the greens were (and still are) korai. Korai is Zoysia matrella – the common name is manilagrass. Everywhere else, the fairways, the roughs, and so on, are noshiba. Noshiba is Zoysia japonica – the common name is japanese lawngrass.

Noshiba in foreground at the edge of the bunker. Korai border immediately surrounding the green. The green surface was formerly creeping bentgrass.

In these photos we see the characteristics of these grasses as they are adapted to this environment. Creeping bentgrass on the green surfaces has been overtaken by weeds. Clearly, creeping bentgrass in this environment seems to require mowing and supplemental irrigation and fertilizer and probably some pesticides in order to persist. It dies quickly without those inputs, or at least it becomes thin, with many voids in the turf that allow for invasion by other species.

The photo above shows a sand bunker in the foreground. Then comes some noshiba with the characteristic autumn symptoms of the wonderfully-named elephant's footprint disease caused by Rhizoctonia cerealis. At the edge of the green surface itself is a band of korai, finer-bladed than the noshiba. And then the green, now a weed patch.

View of an abandoned green complex from a high vantage point, showing the rapid colonisation of a creeping bentgrass putting green by weeds.

The korai and the noshiba both persist at this site for at least two years. It looks like some mowing of the korai and noshiba would get these surfaces back to acceptable condition by next summer. But the bentgrass is beyond saving. Because the korai and noshiba persist, it is evident that they survive without irrigation, and without fertilizer, and that the mowing, and perhaps some weed control, are all that are required to keep them at a minimal level of performance.

The dense korai turf is the most resistant to weed invasion when formerly maintained turf was abandoned for 18 months in the Tohoku region of Japan.

There are various implications of these observations on weed invasion of abandoned turf. This supports something I've written about before: for large areas of maintained turf, it makes sense to use a grass that won't die. Then one will be assured that with minimal maintenance, the quality will be acceptable. And with intensive maintenance, that grass that won't die will be able to tolerate every type of aggressive maintenance, allowing one to produce high performance turfgrass surfaces.

Korai forms a denser turf than noshiba and this is reflected in the relative amount of weed invasion in abandoned turf.

In this case, and at most golf courses in Japan, this good practice of grass selection is used. The creeping bentgrass area is small, less than 5% of the maintained turf area. So the grass that dies, the grass that requires intensive inputs, is planted only on a minimal area. The grasses that don't die, and that require relatively fewer inputs of irrigation, and fertilizer, and pesticides, and mowing – in this climate these are korai and noshiba – are used on more than 95% of the maintained turf area.

Jason Haines shared an interesting report about clover (or actually, the lack of it) on tees at Pender Harbour GC in Canada.

I noticed something crazy. All the clover on the tees had disappeared ... until 2005 we would spot spray these areas with Killex [2-4-D, MCPP, Dicamba] but haven't applied any type of herbicide since then. Today I could only find one small patch less than 1 m² on my tee boxes. Crazy!

So what the heck happened to the clover? ... I was not trying to rid the tees of clover in any way. This was an indirect consequence of something that I did ...

Since 2012 I have really only applied nitrogen and wetting agents to the tees. This combined with the lack of liming has, in my opinion, led to the disappearance of the clover ... and the tees have never been better in the 13 years I have been here. Just nitrogen, wetting agents, and some aeration every now and again. No "weeds." Super quick divot recovery. As close to perfect as I can expect.

I was pleased and pleasantly surprised to find that this result had happened so quickly at Pender Harbour, and it reminded me of the results at the Park Grass experiment in 1857 and 1858, as reported by John Bennet Lawes and Henry Gilbert in their Report of Experiments with different Manures [fertilizers] on Permanent Meadow Land in 1859. 

Different species growing on plots at the Park Grass experiment in 2006 as a result of different fertilizer and liming treatments; the plot in the foreground has received ammonium sulfate applications since 1856. Clover does not grow in this plot, but grasses do.

At Park Grass, the differential fertilizer treatments were applied to the meadow for the first time in 1856. The experiment continues to this day The purpose at the start was to evaluate the effect of fertilizer treatments on hay yield and nutritive value of the hay. But what they noticed, almost immediately, was something unexpected (very similar to that "crazy" disappearance of clover at Pender Harbour). Remember, this is what they noticed immediately, at the very start of the experiment:

Perhaps the most remarkable and interesting of the effects of the different descriptions [types] of manure [fertilizer], upon the complex herbage of which the experimental meadow was composed, was the very varying degree in which they respectively developed the different kinds of plants ... the experimental ground looked almost as much as if it were devoted to trials with different seeds as with different manures [fertilizers].

In the second year of the experiment, 1857, and again in 1858, the proportion of different plant species were measured in the different plots immediately after cutting the field. They reported the 1858 results as I quote below – note that I have changed the word manure to fertilizer for clarity in modern usage.

Perennial red clover [Trifolium pratense] amounted to little more than 1 per cent. of the total produce on the unfertilized land, but to nearly 18 per cent. of that grown by mineral fertilizers alone. Not any of it was found in the produce by either ammoniacal salts alone, or ammoniacal salts in conjunction with mineral fertilizers. There was little more than 1½ per cent. of it in the produce by farmyard manure alone, and less than ½ per cent. in that by farmyard manure and ammoniacal salts.

That is, in the second year of the experiment, there was 18 times more clover where mineral fertilizers were supplied in the absence of nitrogen. Adding ammonium sulfate, or ammonium sulfate with other minerals, eliminated the clover.

At the same rate of N, but applied in the nitrate form, and with P, K, and Mg added as well, many "weeds" including clover grow along with the grasses.

The implications of this for turf managers are pretty obvious. Fertilizer applications have an effect on what grasses and weeds will grow. Judicious selection of fertilizer can help to reduce weed populations. Herbicide use can be reduced or eliminated in some situations by adjusting the fertilizer applications. For more on this, see:

• The Park Grass Experiment and the Fight Against Dogma
• Where did all the clover go?
• Nutrient supply and plant species diversity
• Biological weed control via nutrient competition: potassium limitation of dandelions
• Soil nutrition and weed management TurfChat (video embedded below)

Last week I was browsing the Sir John Bennet Lawes timeline and discovered this excellent video with plant ecologist Jonathan Storkey introducing the Park Grass Experiment.

The Park Grass experiment at Rothamsted was started in 1856 and has been continuously monitored ever since. That makes it the oldest experiment on permanent grassland in the world. 

The experiment was designed to investigate the effects of fertilizer application on hay yields. But what was quickly seen, within the first years of the experiment, was that application of the different fertilizers caused different species to grow. Lawes and Gilbert, in their first report on the experiment, remarked that:

The plots had each so distinctive a character in regard to the prevalence of different plants that the experimental ground looked almost as much as if it were devoted to trials with different seeds as with different manures [fertilizers].

C.V. Piper wrote in 1924, after a visit to Rothamsted, that the Park Grass experiment results "carry lessons of high importance in the growing of golf turf." These lessons extend to any kind of turf, including lawns. I wrote about this with Frank Rossi in The Park Grass Experiment and the Fight Against Dogma. The fertilizers that you apply will influence the species that grow, and the Park Grass experiment is the archetype of this effect.

The types and rates of fertilizer and lime applied to the Park Grass experiment result in dramatic differences in species composition and plot appearance

Related articles

Nutrient Supply and Plant Species Diversity

Presentations in Pennsylvania and Park Grass: nutrient use and nutrient requirements for turfgrass

Why it is Not Important to Maintain Soil pH Between 6.5 and 7.0

Five More Articles Every Greenkeeper Should Read

This is one of those "if I were a greenkeeper today, this is how I would do it" type of stories.

At the Bethpage maintenance facility; research here demonstrates that use of EIQ can reduce environmental impact from 33 to 85% while producing the same quality turfgrass

I was pleased to read the update from Jason Haines about his use of the EIQ (environmental impact quotient) and the results he is getting. He reports that he is ahead on cost goals, ahead on EIQ goals, and that "the greens here have never been better." That sounds like a win-win-win situation.

The EIQ Field Use Rating based on formulation and application rate allow turf managers to identify and choose products based on their predicted environmental impact. From the New York State IPM Program, which administers the EIQ:

By using the EIQ model, it becomes possible for IPM [integrated pest management] practitioners to rapidly estimate the environmental impact of different pesticides and pest management programs before they are applied, resulting in more environmentally sensitive pest management programs being implemented.

Because of the EPA pesticide registration process, there is a wealth of toxicological and environmental impact data for most pesticides that are commonly used in agricultural systems. However, these data are not readily available or organized in a manner that is usable to the IPM practitioner. Therefore, the purpose of this bulletin is to organize the published environmental impact information of pesticides into a usable form to help growers and other IPM practitioners make more environmentally sound pesticide choices.

Jennifer Grant wrote about the use of EIQ Field Use Ratings in research projects at Bethpage State Park. The results there?

Using the Environmental Impact Quotient (EIQ) as the measure, impact was reduced on progressive IPM/alternative culture greens by 33%-85% compared to the conventional pest management/conventional culture greens — almost always without a loss in quality.

The EIQ incorporates the toxicological and environmental impact data for pesticides and makes it easy for turfgrass managers to compare the products they might use, allowing them to choose the one with a lower EIQ — a lower environmental impact.

Various interesting posts hide in the back pages of blogs, and I've enjoyed seeing which of the posts from the early years of this blog were most popular, as measured by the number of pageviews.

Continuing with the lists of top posts by year since the inception of this blog in 2009, here are the 5 posts with the highest pageviews from 2011:

1. An Interesting Technique to Modify Fairway Conditions in Thailand
2. Sandcapping or topdressing: which is better?
3. A Report From the 2011 Golf Course Maintenance Management Conference
4. Research on Weed Populations in Malaysia
5. How Much Potassium Does Turfgrass Need?

I previously listed the 5 top posts from 2009 and the top 5 from 2010.

Grazed native grass near Mysore, India

I'm sometimes asked what grass species should be used for a deep rough on a tropical golf course. Golf course architects or golf course developers sometimes want something that can provide a contrast to the highly-maintained fairways, yet still remain playable. "Something that looks and plays like fine fescue," I've heard.

In Southeast Asia the grass planted frequently in these areas is bahiagrass (Paspalum notatum). But one struggles to find a ball hit into this grass, let alone play from it, and I advocate a different approach.

Bahiagrass rough in Surat Thani, Thailand

I know this type of surface can be produced in a tropical environment. I've written about it in Golf Course Architecture magazine. But my approach involves management, not planting a specific species, and certainly not planting a monostand of bahiagrass.

Grazed warm-season grasses, primarily Chrysopogon aciculatus, in Bohol, Philippines

By looking at the landscape around tropical parts of Asia, one sees that this type of wispy rough, one which would provide a contrast to the maintained fairway, and one in which one could easily find and play a golf ball, is actually quite common. 

From fields grazed by sheep in India to fields grazed by cattle and goats in the Philippines and Japan, these grasses, no matter what they are, produce a wispy tall rough. These areas are not fertilized (except by the animals), are not irrigated, and clippings are harvested. On golf courses, a similar surface could be produced by simulated grazing. Withhold irrigation, don't fertilize, mow infrequently and remove clippings. If the grass grows too fast, slightly compact the soil to reduce the amount of water and soil nutrients available to the grass.

Grazed pasture at Ishigaki, Japan; low-growing grasses are primarily Zoysia and Digitaria species; tall grass clumps are Sporobolus indicus