Preparing for Winter

Last year's winter proved to be one of the longest coldest winters that we have experience in this area in quite some time.  As a result we lost some turf, primarily on greens 4, 5, and 6.  I wanted to share with you some changes that we have made heading into this winter that will hopefully reduce the likelihood of this type of damage from occurring again.

First you need to understand what leads to turf loss in the winter.  The main causes of turf loss in the winter include; crown hydration, low temperature kill, desiccation, fungal diseases and ice sheets.  Let's examine each of these and find out what we have done to help prevent them from causing damage this winter.


Crown Hydration.

In the fall grass plants prepare themselves for winter by moving water out of their cells (de-hydrate).  This process commonly referred to as hardening off.  If plants did not go through this process, the water in their cells would freeze, expand and rupture the cell walls causing the plant to die.  Some grasses, particularly Poa annua, when exposed to warm temperatures are quick to re-hydrate their cells.  If the warm temperatures that caused the plant to re-hydrate are then followed by a period of cold temperatures the cells could rupture.  This typically occurs in the late winter or early spring.

If you allow grass plants to set in above freezing water during the day as the snow melts and then expose the plants to cold night time temperatures you greatly increase your chances of turf loss through crown hydration.  Anything that can be done to prevent water from running onto the green and then getting it off the green as quickly as possible will help reduce the chance of this type of damage from occurring.

First we looked at how we might help the water get off the greens quickly.  When inspecting #4 and #5 greens we could see that the collar in front of the green was at a slightly higher height than the green surface.  Caused by years of applying sand topdressing to the greens, this sand build up in the collar was essentially creating a dam.To fix this we stripped the sod in front of the greens, re-graded the soil and then replaced the sod.

Lowering the front of #4 green

We also performed a deep tine aeration on greens 4, 5 and 6.  We used a special aerifier that used solid 1/2" diameter tines that went down 10" deep into the green.  Our plan is to leave these holes open so that as the snow melts the water will run down into these holes and keep the crowns of the plants from sitting in a pool of water.

Deep tine aerifying #4 green

Next we looked at preventing water from flowing onto the greens.  The 5th green and the 6th green both had areas that could be improved so that less water would run onto the greens.

On the 5th hole we installed a drain line and catch basin to the left of the green.  Our hope is that this new drainage will catch water coming off the hillside and direct it away from the green

Installing drainage on the hillside above #5 green

Likewise on the 6th green we identified an area where water from the cart path was moving down onto the green.  To correct this we added some mounding along the cart path which will divert water away from the green.

Preparing to add mounding along #6 cart path

Low Temperature Kill and Desiccation

Just as the name suggest low temperature kill is caused by exposing the turf to extremely low temperatures particularly when the weather changes rapidly and you get a drastic drop in the temperature.  Bentgrass can tolerate temperatures down to -30 degrees while poa annua can only tolerate temperatures down to -10 degrees.

Desiccation can also lead to turf loss and is caused by cold winter winds blowing across exposed turf leading to the plants to drying out.  The best insurance against both these types of damage is a good layer of snow.  Snow is a great insulator and the temperature at the surface under the snow will typically be right around 32 degrees even on the coldest days.

Unfortunately snow is not always present in the winter so to help protect the turf from these two forms of damage, late in the year, we apply a heavy layer of sand to the greens.  This layer of sand covers the crowns of the grass plants and acts to insulate the plants.

Topdressing greens with sand

Fungal Diseases

Fungal diseases that occur in the winter are generally called snow mold.  There are two types of snow mold, gray snow mold and pink snow mold.  Gray snow mold requires extended periods of snow cover while pink snow mold can occur with or without snow cover.  Both types of snow mold can cause extensive damage over the winter.  To prevent this we apply a protective fungicide late in the year to the greens, tees and fairways.

Spraying for snow mold

Ice Sheets

While snow is beneficial to the turf in the winter, ice is bad.  One of the hardest decisions to make in the winter is when and if to remove ice from the greens.  The rule of thumb is that Poa annua can survive 60 days under continuous ice cover, while bentgrass can tolerate 120 days.  We will closely monitor the formation of ice on the greens this winter so that we know how long the ice layer has been on the greens.  Even after knowing how long the ice has been on the green, the decision to remove the ice or not remove the ice is not an easy one.  Sometimes the process of removing the ice can do more harm than good.  Also once the ice is off the greens you then expose the turf to low temperatures which could also lead to turf loss.  Never the less, we will keep a close eye on things and cross that bridge when we need to.

One way to help prevent ice from remaining on the greens for long periods of time in the first place is to allow more sunlight to reach the greens.  If you look at the greens that were damaged last year you will notice that they all share the same characteristic of being surrounded by dense trees.  Without sunlight reaching these greens during the day the ice tends to last much longer on these greens than it does on other greens.  To help correct this we have removed several trees around these greens but more will likely need to be removed in the future.

Tree removal to allow more sunlight to reach #6 green

As you can see we have taken several steps to help prevent loosing turf again this winter.  However there are no guarantees. Ultimately we are still at the mercy of Mother Nature.  Hopefully with some good preparation, some close monitoring and a little luck we will make it though the winter unscathed and be ready to go next spring.

Getting ready for winter

We just finished winterizing our irrigation system.  It is an important to procedure.  If we did not winterize the system the water in the plastic pipes would freeze and crack the pipes.

To remove the water we rent a large air compressor.  The compressor gets hooked up to the irrigation line outside the pump house near #7 fairway.

Air compressor at pump house

Once we have enough air pressure built up in the lines, we turn on each irrigation head until the water stops flowing out and it is just blowing compressed air.  At times it looks like Yellowstone Park out there.

Removing water from the irrigation heads

We also have a transfer line that runs from #12 to #7 that needs to be blown out.  The whole process generally takes about 10 to 15 hours to complete.  This year we managed to finish winterizing the irrigation system on Tuesday November 25th, one day before we received 8 inches of snow!

When It Rains It Pours

After experiencing heavy thunderstorms the evening before, we came in on the morning of July 3^rd to find this. 

An irrigation pipe leading to a quick coupler valve had broken next to the 13^th green.  The water ran through the night and eventually washed away a section of the collar and part of the green.

Thanks to the efforts of my irrigation tech Chris Wargo along with some other members of our greens staff, the repairs were quickly made and the next day the green looked like this.

Maintaining a golf course is a big job.  It takes the dedication and hard work of a team working together to pull it off.  I just want to take this opportunity to thank my staff for all their hard work and to say keep up the good work.

Root Pruning

Last summer we began experiencing severe drought symptoms on a few of our tees  No matter how much water we applied, these tees would constantly dry out.  After probing around in the soil we realized that the roots from nearby trees had grown into the tee mix and were causing our problem.  After seeing the impact tree roots can have, I realized that certain areas of the rough that consistently burn out during the summer were similarly being negatively effected by tree roots.

To help solve this problem we rented a machine to prune back the tree roots.  Pruning tree roots is a common practice on golf courses.  Traditionally root pruning is performed every 4 or 5 years and is done using a ditch witch trenching attachment.  This method involves first the removing the sod, then digging a trench with a ditch witch.  The open trench is then back-filled with soil, compacted and the sod replaced.  It is a time consuming and labor intensive process.  The machine we rented cuts through tree roots in very little time with minimal labor.  Two large rotating blades slice through the soil and through any tree roots.  All that is left behind are two thin lines in the turf. 

Later this summer as things dry out we will see the benefit of this process.  Without the competition from the tree roots we will have a better chance of maintaining quality turf throughout the summer.

Pruning tree roots

The imants root pruner

Blades of root pruner

No clean up necessary

Easily cuts through large tree roots

#5 Green on May 20, 2014

Although progress has been made, recovery of the winter damaged greens continues to be slow.  A cool spring has slowed the growth of the grass and delayed seed from germinating.  However as the weather continues to warm up I am confident we will see faster recovery.  To speed the process along, we decided to sod the most heavily damaged areas of the collars on the 4th and 5th green.

Re-sodding #5 collar

We also have been taking plugs of bentgrass from our nursery green and plugging out the worst spots on the greens.

Removing bentgrass plugs from nursery green

Repairing #4 green with bentgrass plugs

Course Update

Beginning Sunday afternoon and ending Monday evening we aerified and topdressed all 18 of our greens.  The greens were aerified using 3/8" hollow coring tines on 1 inch centers.  After the plugs were cleared off the greens, sand was applied and worked into the open holes. Today fertilizer will be applied to get the grass growing. We will roll the greens daily to smooth and firm the surface and in a few days after the sand has settled into the canopy we will start mowing the greens.  Because the growth of the grass tends to be a little slower in the spring, we like to use the smaller 3/8" tines to shorten the recovery time.  The greens should be completely healed in about 2 weeks.  Although aerification is despised by golfers and maintenance staff alike aerification remains an important cultural practice.  Aerification removes unwanted thatch and allows good air exchange to the root system helping the turf to survive the stresses of summer.

The fifth green continues to recover nicely although it never seems to happen as fast as we would like.  The cover definitely helped speed up the recovery process and allowed us to get the bentgrass seed to germinate.  As temperatures continue to rise and the green recovers, the green will be available for limited play and eventually be open all the time.  Looking at the green every day, it is sometimes hard to see the progress we have made.  Here are some before and after photos that show how far the green has come in one month.

#5 Green on April 16, 2014

#5 Green on May 10, 2014

#5 Green on April 7, 2014

#5 Green on May 10, 2014

Bentgrass creeping over damaged areas

New Bentgrass seedlings

Road to recovery

The road to recovery has begun.  On Friday April 25th we over-seeded the 5th green with creeping bentgrass.  The following is a description of  the process we used.

The first step is to prepare the green for seeding by using a special tool called a Job Saver tine. These tines make small shallow holes in the green that hold the bentgrass seed.

Aerifying #5 Green with Job Saver tines

Holes made by Job Saver tines

 Next we seeded creeping bentgrass into the open holes.

Seeding with bentgrass

 Once the seed is down, we apply a layer of sand to the green and then work the sand into the holes with a drag brush.

Topdressing with sand

Brushing in the sand

After the sand is brushed into the holes we roll the green, irrigate and cover with a tarp.  The tarp will act like a greenhouse to help heat up the soil.  For bentgrass seed to germinate we need soil temperatures in the 60 degree range.  With the right environmental conditions bentgrass usually germinates in 5 to 7 days.  We still have a ways to go but these are the first steps in getting the greens to recover.

Holes filled with sand and seed

Tarp covering green

Winter of 2014

After experiencing one of the longest coldest winters in recent memory, we have anxiously awaited to see what effect it would have on the turf. While most of the turf came through the winter fine, it is now apparent that we did suffer winterkill on a few of our greens.  The damage is most noticeable to the Poa annua on greens #4, #5 and #6.

Winterkill on #5 Green

WinterKill

Poa annua or annual bluegrass is a grass species that is particularly susceptible to winterkill primarily through a process known as crown hydration.  Crown hydration generally occurs in mid to late winter when a day or two of warm daytime temperatures causes snow to melt and collect in low areas.  The combination of warm temperatures and available water enables the grass plants to start absorbing water or hydrating.  If the warm weather is then followed by freezing temperatures, ice crystals form in the plant, rupturing cells and ultimately causing death.  Annual bluegrass tends to break dormancy quickly when subjected to above-freezing temperatures and free moisture and therefore is very susceptible to this kind of damage.  Creeping bentgrass on the other hand is late breaking dormancy and is virtually immune to crown hydration.  This is why when you see the greens that were affected you will notice that the annual bluegrass is severely damaged while the creeping bentgrass is very healthy.

Damaged Poa annua and healthy bentgrass

Recovery

In the short term we will look to reestablish the damaged areas of the greens as quickly as we can.  However this process can be agonizingly slow and challenging in the spring because of the cool, cloudy conditions that often persist.  The first step in promoting recovery is getting seed into the ground.  Once the weather warms and soil temperatures increase, we will begin the process of inter-seed creeping bentgrass into the damaged areas.  Although inter-seeding has given mixed results, success can be improved by using new improved bentgrass varieties and by utilizing tools such as the Job-Saver aerator attachment.  This tool produces numerous small, shallow holes for the seed to germinate in.  After seeding it may be necessary to apply a turf cover over the green to maintain adequate soil temperatures for germination to take place.  

Turf Cover on #5 Green

The second step to successful recovery is keeping traffic off the greens. Traffic sets tender, weak turf up for more injury.  Also newly emerging bentgrass seedlings are susceptible to wear injury.  Opening greens too early usually doubles the recovery time, and it reduces the amount of bentgrass established.  While no one hopes for winter injury, it does provide an opportunity for the existing bentgrasses to increase and to establish new and improved species of bentgrass. By increasing our bentgrass populations we would be less likely to encounter this type of damage in the future.  Other strategies employed in recovery will include reducing stress by mowing and rolling these greens less frequently, raising mowing heights, using solid front rollers on the greens mowers and providing light frequent fertilizer applications to stimulate new growth.  How long the recovery will take is difficult to say.  A lot will depend on the weather but I suspect it will take several weeks to completely heal. 

Winter Update

As winter continues to linger there is a growing concern among many superintendents in the northeast as to what effect this winter will have on the turf. 

Snow cover is good for the golf course.  Snow acts as an insulating blanket that protects the grass from the extreme low temperatures and harsh winter winds.  Ice on the other hand is not good.  Ice covering the turf prevents CO₂ gas from escaping into the atmosphere.  Prolonged exposure to high levels of CO₂ can lead to turf loss.  As a rule of thumb bentgrasses can tolerate up to 120 days under ice cover while Poa annua can only survive about 45 days.  Because our greens at Huntsville are a mixture of bentgrass/ Poa annua and we are approaching 45 days under snow and ice coverage, my assistant Casey Sheehan and I went for a walk around the course to inspect the greens for possible injury.

Our first stop was the 8^th green.  This green was covered with about 3 inches of snow and a 1/2” thick layer of ice.  We removed the ice and looked at the turf underneath.  Everything looked good.  Most importantly, when we uncovered the turf, we were not meet with “the smell of death”.  “The smell of death” is a term superintendents like to use to describe the odor that dead turf gives off under ice.

Next we proceeded down to the 4^th and 5^th greens.  These greens had about 5 inches of snow covering a 2 inch thick layer of ice.  The thick ice and melting snow made it a little harder to see the turf but from what we observed the grass still looks good.

We also took a small sample of the green and brought it back the maintenance building for observation.  If the grass greens up and starts to grow, we will know that the turf is still healthy.

There is much debate about the best way to deal with ice on a green.  Some superintendents choose to remove the ice.  However there are two problems with removing the ice.  First, the process of removing the ice itself can cause significant damage to the green.  Secondly, if you remove the ice and expose the turf to warm temperatures and then get a period of low temperatures you can lose turf through what is known as crown hydration.

Based on what we have observed so far, we have decided to leave the snow and ice in place and continue to monitor the health of the greens.  If it is determined that the ice is causing problems then at that point we will take the necessary steps to prevent further turf loss.

Some parts of the golf course have already lost its snow cover.  All of these exposed areas look good.  We have not seen any ice damage and there is no sign of snow mold.  Snow mold is a fungus that can attack the turf in the winter.  We treat for this disease preventativly in the fall and I am happy to say that those applications seem to have been effective.

With warmer temperatures in the forecast, we hope to loose a lot of the remaining snow cover and prevent any ice damage from occurring.