|Keith changing cups - June 23rd|
Keith graduated from Elmhurst College and is moving to North Carolina to continue his studies. We will miss his level plugs and relentless fixing of ball marks. Good luck, Keith!
|Keith changing cups - June 23rd|
Above is a look at roughstalk bluegrass (Poa trivialis) which makes up a large portion of our fairways and tees at Sugar Creek. It is considered a weed and was not planted intentionally. The "trivialis" in the plant's Latin name indicates that it is very common, not trivial. This member of the bluegrass genus is an invasive species from Europe that can be found growing wild in most areas of North America. It spreads aggressively by seed and stolons (stems that run along the ground) during the spring and fall. It does not, however, like our summers.
In many previous posts, I have discussed the difficulties of dealing with Poa annua, or annual bluegrass, on golf course turf. I occasionally mentioned Poa trivialis (or roughstalk bluegrass) along with its annual, bunch-type cousin. Because Poa annua affects putting greens it often gets more press than P. trivialis. You may hear superintendents just say "Poa" as shorthand for both weeds, but there are major differences in the their life cycle and growth habit. After working with both for quite some time, I am finding that P. trivialis is a far greater problem for our fairways and tees than annual bluegrass.
The problem with Poa
Poa trivialis is commonly called roughstalk bluegrass -- but not due to any roughness of its shoot tissues. The rough "stalks" are the stolons that creep along the ground sending tender shoots upward and tiny roots downward. Roughstalk bluegrass actually has soft, fine blades that are tightly spaced when mowed regularly. It can easily be mistaken for creeping bentgrass without close inspection. Below is the 4th tee looking good in June. It is mostly Poa trivialis.
|4th tee - Mostly Poa trivialis|
Poa trivialis looks good and plays well most of the year. It would make a decent turfgrass -- except for one BIG problem. It completely shuts down during hot weather. The grounds crew successfully kept it going through very dry conditions by handwatering and syringing through the day, but the heat wave in early July with 3 consecutive 100 degree days caused large areas of Poa trivialis to decline from heat stress.
July 5th and 6th -- the 2nd and 3rd 100 degree days -- were brutal on cool-season turfgrass. Simply put, grass species in our area are not adapted for optimal growth during the summer. They are adapted for the cooler seasons of spring and fall. Kentucky bluegrass, creeping bentgrass, and ryegrass can often take one extremely hot day under the right conditions, but several in a row is a different story. Turf managers attempt to coax an often unwilling plant through the rough patch of summer when stress and play are at their highest. It doesn't always work.
In the photo below taken the morning of July 6th you can see patches of turf in the process of going dormant due to heat stress. You can also see some cart tire tracks turning purplish-brown. That afternoon was the breaking point for a lot of Poa trivialis and Poa annua:
|7th fairway morning of July 6th - Patches going dormant|
Why is it here?
Poa trivialis is everywhere. Small amounts can come with regular Kentucky bluegrass and ryegrass seed -- especially in the past. It is possible that it was in the original seed used on the course, but it is just as likely that seed and stolons were already here before the golf course. These areas have been seeded and sodded many times over the years just to be over-taken by Poa species.
We have the perfect conditions for Poa. Poa trivialis thrives during spring and fall in compacted and poorly drained soils. Many of our fairways are made up of clay mixed with rock, asphalt, brick, and concrete from the old rock dump on the site. Here is a soil profile from a random spot on this fairway:
|Clay mixed with bits of asphalt, brick, and gravel|
This picture was taken 12 hours after a heavy rain. The soil problems are compounded by poor drainage. Unfortunately, the design of the course routes a large amount of water through the middle of the fairway. Some drains have been added over the years in these wet spots but they are not adequate to move lots of water quickly. The result is that puddles stay in the fairway for days after a thunderstorm. The 7th fairway is especially bad.
|7 fairway after heavy rain|
The puddles perfectly line up with the areas of dormant Poa trivialis because the poor drainage encouraged this grass in the first place and discouraged desirable species of bentgrass or bluegrass. Under the right conditions these puddles also heat up and scald the turf.
The turf in these areas is not technically dead. It is just dormant. When it dries out, you can peal up the turf and see new shoots forming on the stolons and some seedling germinating.
These seedlings may be Poa annua or trivialis, but they are seedlings and not connected to stolons:
So far, we have used slicing tines on the fairways and tees to encourage some gas exchange. We will also be slit seeding and aerifying during August to speed recovery and try to establish hardier species of grass.
Can you get rid of it?
Poa trivialis is almost diabolically difficult to control because it can lay dormant for long periods. In 2010 and 2011, we slit seeded these areas with bentgrass. The seed germinated in August and began establishing only to be overwhelmed by Poa annua and Poa trivialis in September and October. Without removing the existing turf and starting fresh, it is difficult to impossible to permanently establish a desirable turfgrass.
There are two ways to get rid of it: Multiple applications of non-selective herbicide (Round Up) or physical removal (total renovation). There is research on a selective herbicide (Velocity) that can weaken it in a mixed stand but would not be effective in this situation. The underlying cause of Poa also needs to be dealt with: poor drainage and poor soil.
Because it is not possible to eradicate without a total renovation, we try to keep as much alive as possible during the summer months. In years like 2009, it was possible to keep it all alive. The past two summers it has not been possible due to extremes in heat and moisture.
How can we speed up recovery?
We do several things to speed up recovery and limit further damage:
In 2011, August was fairly mild with only 3 days over 90. An August like that would be ideal for recovery. Here is some slit seeding from 2011:
- Maintain adequate moisture when it does not rain
- Limit cart traffic to affected areas
- Use lighter mowers or walk mowers on affected areas
- Aerify multiple times
- Topdress affected areas
- Slit seed
- Sod worst areas if necessary
- Maintain proper fertility
|Slit seeding on #1 fairway in 2011|
Most of these seedlings were overwhelmed by Poa the following spring, but the slit seeding did significantly speed up recovery last fall. We are going to keep experimenting with techniques to establish more desirable turfgrasses in the middle of Poa trivialis this year. Stay tuned . . .
The week of July 4th, 2012, is not one we are going to forget any time soon. It started with 1.5 inches of rain and a violent wind storm on Sunday afternoon. Power was knocked out in the area for at least a day -- many days for some residents. To add insult to injury, a heat wave set in making the work of clean-up crews uncomfortable and potentially dangerous. At Sugar Creek, the crew quickly went from storm clean-up on Monday and Tuesday to trying to cool extremely hot turf the rest of the week.
The wind storm on July 1st left the course covered in debris. Most of the greens looked like this:
|5 Green - July 1, 2012|
The storm brought down many large limbs that had to be cut up and chipped. 4 fairway in particular was covered in limbs from the large Cottonwoods on that hole.
|4 Fairway - July 1, 2012|
On the 9th tee, the wind knocked over a Norway Spruce. Spruce are shallow rooted in clay soil and can be pushed over in heavy winds. We were successful in standing this tree back up, but it may still decline from the loss of roots on one side.
|Norway Spruce on 9th tee|
This poor Bald Cypress had its top taken off. It has a vertical branch that looks like it will turn into a new leader. It will have a "unique" shape but will survive.
|Bald Cypress on 6th fairway|
The rain came down so hard that it washed out all of the sandtraps. Events like these are why our sand has become mixed with debris and clay from the top edge of the trap. I was just reading an article that stated: "Principle one is that no surface water should enter the trap. Of all principles in sand trap construction, this one is paramount" (Daniel, Golf Superintendent). The designers and builders of our sand traps must not have read that article. To be fair, I'm sure they were aware of the surface water issue but sometimes visual impact, construction cost, and placement of the hazard are put before playability, maintenance cost, life span, and reality.
|July 1, 2012|
The grounds crew had the course playable by Monday morning at 6:30 am using a combination of mowers, blowers, chainsaws, tractors, rakes, and pitchforks. Tree work continued into Tuesday, but then it was time to turn our attention to the extreme heat on July 4th, 5th, and 6th. Around 3pm each day, I measured 2 inch soil temperatures over 100 degrees in our historically weakest areas. The underlying soil in these areas was still moist from the 1.5 inches of rain on Sunday so lack of water was not the issue. Cool season grass roots simply cease to function at these temperatures. All we could do is syringe these areas carefully to cool them down. Syringing lowered the canopy temperatures in these areas to 94 degrees temporarily. Not great, but an improvement over 100.
You know the turf is under extreme stress when your footprints stick in previously very healthy turf:
|Stressed turf - July 6, 2012|
Below Gary is syringing, or misting, stressed portions of fairway. Last week, we were hand watering dry soil and drought stressed turf with high flow nozzles meant to re-wet dry soil. This week, we are using misting nozzles to cool the turf through evaporation and perhaps get the plant to take in small amounts of water during this cooler period. The cooling effect lasts only a short period of time. Significant effects are gone after 15 minutes but this can be enough to get some turf through the stress period.
|Gary syringing #1 fairway|
This picture was taken on July 6th at 1pm in the shade! I would expect this temperature when solar radiation was added to the mix, but I was surprised to see temperatures over 100 degrees in healthy turf with some shade during mid-day.
One thing is for sure: Next week will be just as busy at Sugar Creek. With cooler weather, we can take steps to speed up the recovery process on tees and fairways through cautious solid tine aerification and irrigation practices. We have to be careful not to do more harm than good in our attempts to help the turf recover.
We are definitely thankful for this forecast. Especially the night time lows in the 60's. Looks like a beautiful week for golf -- and turf recovery:
Many area courses are restricting cart traffic during extreme heat. A few photos from this morning show why. On days of extreme heat, grass plants are so stressed that simply driving over them causes death. This type of damage usually occurs during the middle of the day when conditions are the most uncomfortable for people and plants.
If your local golf course is restricting cart use, please understand they are trying to save the course for the rest of the year. Tire tracks like this take a long time to heal:
In these areas, I measured soil temperatures at a 2 inch depth close to 100 degrees on July 4 and 5. Healthier areas of fairway were 94 degrees. Soil composition and characteristics very widely on our fairways so it is impossible to tell without a probe where the hot spots are.
In most areas, the course is holding up to the heat but areas are starting to run out of energy reserves and root mass. 100 degree soil temperatures literally cooks the cells of cool season grass plants. Our fairways are the most sensitive due to how they were built and the soil they were built on. They also contain a fairly high percentage of Poa annua or annual bluegrass. In most areas the soil is heavy clay mixed with pulverised concrete and asphalt. As you can imagine, they tend to heat up fast.
The grounds crew is very busy trying to keep as much turf alive as possible through this period of record high temperatures. You may also see hand watering or irrigation heads running to cool the turf. The purpose of this "syringing" is to cool the plants through evaporation -- not to wet the soil. This practice works only in certain circumstances and must be employed carefully. During these hot periods, too much water is just as bad as too little.