Growing Degree Days

Thank you Purdue and MSU for this explanation, which I think is pretty good:

What is a Growing Degree Day (GDD)? A growing degree day (GDD) is a method to track the heat units that have accumulated and are needed for plant growth and development. The formula for calculating GDD is:
GDD = ((max temperature °F + min temperature °F) ÷ 2) - base temperature °F, where the base temperature is normally either 22, 32 or 50 °F but varies based on the model.

For example, if the high today was 74°F and the low was 52°F and we used a base temperature of 50°F, our calculation would be, GDD= ((74°F + 52°F) ÷ 2) - 50°F = 13 

Models that help us predict plant development use accumulated GDD which is simply adding the GDD calculated each day and determining how many GDD units have accumulated thus far.

In some cases accumulated GDD can be used to monitor when weeds might germinate or flower or when grasses might produce a seedhead while in other cases accumulated GDD can be used to help optimize application timing such as with preemergence crabgrass applications or the selection of amines or esters for spring broadleaf applications. Research into plant development and optimal herbicide application timing has determined a window of accumulated GDD needed to best predict when to time these applications or when these events might occur.

 

 

Frost

Frost is formed when the temperature of a solid surface is cooled below the dew point.

Frost on objects is just water vapor in the air that has condensed as ice onto a surface. Frost forms on objects close to the ground, such as blades of grass. At night, a blade of grass loses energy by emitting a non-lethal kind of radiation, but it absorbs energy emitted by surrounding objects. Under clear nighttime skies, objects near the ground emit more radiation than they receive from the sky, and so a blade of grass cools due to the net energy loss. Once a grass blade gets cold enough, frost will form on it.

 

Overnight cooling of air near the ground causes morning frost on grass and car windshields. Frost will only form on a surface that is at or below freezing temperature. The observed air temperature may be above 32 F, since observations are taken at about four feet above the ground, where it can be warmer. The difference in frost formation from one to the next is most likely due to differences in elevation.

 

 

 

Aerification

It's just 2 weeks away: September 2nd - 4th. If the weather is conducive we'll be able to aerify most of the South Course. Fairways take the longest so those might require another two to three days to complete. Much depends on the weather.

The Correct Record

A lot of information has been communicated about winter damage, snow removal and lost turf at Oakland Hills. How much turf was lost? How many dead greens? Was the North damaged? How much does it cost to remove snow?

 

Much of the information regarding Oakland Hills in the public domain is incorrect. Here are the facts about this past winter, snow removal and our current status.

SOUTH COURSE

• We remove snow from the South greens every winter when we see a potential rise in temperature above 30 degrees. Some of the South greens are covered, some are not. We removed snow this winter after the early January snowstorm and before the meltdown of January 8-10. This action saved the South greens from more severe damage.

 

• Every green on the South sustained some damage, most of it minor. Greens 6, 8 and 12 suffered "serious" (10-15%) damage and only number eight is questionable. We are not playing to any temporary greens as of today, April 29th. Number eight may require a temporary green depending on the level of play. All of the South greens will recover in the next 2-4 weeks. 

 

• The labor cost to remove snow on the South this winter was approx. $5,000.

 

• The extra equipment required to remove snow from the South greens adds approx. $20,000 to our equipment inventory.

• Each cover we use is approx. $3,000, depending on size.

•  It takes 4 - 7 people to remove snow on the South Course.
 
• All of the South fairways incurred some ice damage and most of this will heal on its own.

 

NORTH COURSE

 

• We do not currently remove snow on the North greens. All of the North greens sustained damage. Some of it severe with the most severe #15 green, approx. 30% turf loss.

 

• We will be playing to all of the North greens when we open on May 9th. There are currently no temporary greens on the North Course. The PG did not suffer any winter damage.

 

• There are no "dead" greens on either course.

 

 

 

 

Cold Temps

Part of our winter maintenance program is to clear snow from greens. It helps reduce (not eliminate) the chance of melting snow turning to ice, a dangerous situation on the South Course annual bluegrass greens. The South greens have a history of susceptibility to winter damage.

Ideally, we would leave the snow on the greens when the temperatures are below 25 degrees and remove it when we see the forecast above 30 degrees. Snow cover during exteremly low temperatures provides insulation.

However, open greens during very low winter temperatures also have risk as the survivability of annual bluegrass decreases. All of the South greens are open and exposed to the freezing weather. As of today they look good and we believe they will come through in fine shape. But ... it will be important to understand that annual bluegrass greens are ALWAYS at risk anytime of the year.

Late Fall Aerification

At the end of each season - early November - our maintenance practices shift to "winter protection". Now is the time to give the turf a rest and prepare it for the hardships of winter. Fertility and cultural programs are adjusted, changing from a strictly "play focused" philosophy to a "plant health" centered regime.

Part of that program is to aerify greens deeply: Deep Tine Aerification. We use a solid tine that penetrates to a depth of 8-10 inches, loosening the subsurface and providing channels for melting snow to evacuate the surface. Melting snow that turns to ice is our number one concern for turf loss on the South greens, more of a concern than any risk the turf faces in the summer. Avoiding turf loss in the winter is far more complicated than during the summer months.

Course Closing

WHY DOES THE GOLF COURSE CLOSE NOW AND WHY CAN'T WE USE THE GRASS TEE AT THE RANGE?




At the end of the growing season just prior to dormancy, tufgrass needs to maximize it's ability to survive the extremes of winter. We can help that process by employing practices that enhances the reserve carbohydrate (food) level and general health of the turf. Practices like: limiting mechanical damage from play and cart traffic, applying small amounts of nutrients and raising mowing heights to relieve stress.



In the fall, when the grass stops growing, it cannot recover from damage by carts, foot traffic and mowing equipment. We close the golf courses so they have the best chance of avoiding winter damage and allowing the golfer good playing conditions the following spring.



The Range Tee stops growing too, in mid-October. It's too cold for seed to germinate and any damage incurred now will remain through next spring. By using the matts only, we are insuring a better playing surface next April.

Frost

Frost is basically frozen dew that has crystallized on the grass, making it hard and brittle. A grass blade is actually 90 percent water, therefore it also freezes. Because of the short mowing height (sometimes as low as 1/8 inch) and fragile nature of the turf, putting greens are most affected by frost. Walking on frost-covered greens causes the plant to break and cell walls to rupture, thereby losing its ability to function normally. When the membrane is broken, much like an egg, it cannot be put back together.

Golfers who ignore frost delays will not see immediate damage. The proof generally comes 48-72 hours later as the plant leaves turn brown and die. The result is a thinning of the putting surface and a weakening of the plant. The greens in turn become more susceptible to disease and weeds. While it may not appear to be much of an issue if a foursome begins play early on frost covered greens, consider the number of footprints that may occur on any given hole by one person is approximately 60. Multiply that by 18 holes with an average of 200 rounds per day and the result is 216,000 footprints on greens in a day or 6,480,000 in a month.




As golf enthusiasts superintendents do not like to delay play, but they are more concerned about turf damage and the quality of conditions for the golfer. Frost also creates a hardship on a golf facility's staff as all course preparations are put to a halt until thawing occurs. Golf carts can cause considerable damage, therefore personnel cannot maneuver around the course to mow, change cup positions, collect range balls, etc.



You may see the grounds staff working on the course before play is allowed. The staff must get ahead of play to prepare the course by at least 30 minutes to avoid getting caught by the lead groups.

Wetting Agents

In the prior 24 hours, we received almost 1" of much needed rain. You might ask why we are watering on days it rains. Today was a scheduled "wetting agent" application and these types of products must be irrigated after application. So rain or shine, we water for a few minutes after spraying.

Wetting agents are surfactants.Surfactants modify the surface tension between water and soils or plant surfaces, making it easier for water to infiltrate and moisten the underlying soils. They make water more effective.

Wetting Agents and Fertilizer

It's time to fertilize fairways. This is a season long application with nitrogen available for the next 3 months. We won't fertilize fairways again until late summer or early fall.

At the same time we are applying a wetting agent. Wetting agents help water infiltrate and move through the soil profile, allowing us to irrigate less and making for more consistent playing conditions.

Both of these products needed to be irrigated after application.

Annual Bluegrass Weevil



photo from NC State


Annual Bluegrass Weevil (ABW) was first seen in Conneticut in 1931 and has since spread throughout the Northeast , the Mid-Atlantic region, Ontario and Ohio. While we see no outbreaks on Michigan golf courses yet, because the growing conditions are similar to the Northeast, it is certain to appear here in the future.

The damage comes from older larvae that feed on the growing point of turfgrass, the point referred to as the crown. Once the crown is destroyed, the plant has no chance at recovery and dies. ABW particularly likes close cut annual bluegrass, like putting greens. The damage is severe and the critters are difficult to control as some insecticide resistance has been reported.

ABW is not yet a problem for us at OHCC, but we continue to monitor for its' eventual arrival.

Snow Mold

Snow Mold is a term used to describe several fungal winter diseases of turfgrass; it usually appears in the spring when snow melts. Two main types exist: gray and pink snow mold and they become active under snow cover, although pink snow mold frequently becomes active in the absence of snow in cool, moist conditions.  


Each fall we treat greens, tees and fairways with a fungicide to prevent the disease. It is not practical to treat home lawns for snow mold, but a few cultural practices can be done to lessen the severity.  


1. Avoid excessive nitrogen applications late in the fall.
2. Rake up all the leaves in your yard.
3. If possible, avoid large piles of snow that take a long time to melt.
4. Continue to mow your lawn. Long grass can mat down creating a breeding ground for fungi.    

Fall Deep Tine Aerification

A "deep tine" aerification using a solid (vs. coring or hollow) tine has many benefits.

It leaves an open hole throughout most of the winter allowing melting snow and ice a place to evacuate. These open holes fill with water and freeze, causing the soil to expand and contract. This fracturing of the soil is another way that nature aerifies during the winter and spring.

Late fall aerification provides air an avenue to reach the roots of putting greens. Air is as important as water for the growth of healthy turf.

Topdressing Approaches

One of the fall agronomic practices for us is to topdress greens, tees and approaches with sand.

With approaches, this dilutes thatch, allows us to mow the turf shorter and most importantly it provides a firmer playing surface. Firmer surfaces gives the player more variety in shot making. All of the approaches and tees were topdressed this week.

COURSE CLOSING

The South Course will close for the year after play ends on Sunday, November 4th. This is consistent with prior years. The North Course will remain open as weather permits.

Our efforts this time of year are allocated to promoting healthy turf as we move into winter, particularly on the South greens. The predominance of annual bluegrass in the South greens leaves them susceptible to winter damage from ice and low temperatures.

To combat this we raise the height of cut on greens, allowing more turf surface to capture available sunlight,  thereby producing food (carbohydrates) for a healthier grass plant. Reducing stress on greens in the fall puts them in a better position to withstand the rigors of winter.



Photosynthesis
Carbon dioxide + water in the presence of sunlight, produces food



Driving Range Tee

As of today through the end of the year, we will be using only the matts on the driving range. The grass portion of the tee will be closed. Giving the turf a rest now, allows a little recovery before the winter and puts us in the best position to have a healthy tee next spring.

We raise the mowing height ... or as weather dictates, stop mowing completely. A higher mowing height results in more leaf tissue that can produce food for winter storage. An increase in food storage helps the grass plant withstand the rigors of winter.

Annual Bluegrass

Annual Bluegrass (Poa annua) is a native of Europe and is found worldwide. "Poa", as most members refer to it, likes moist, shady sites and prefers rich, compacted soils. These conditions are typically found on older golf courses and greens like the South Course.

The South greens are original Donald Ross greens (except #'s 7,8,15,12) and are composed of organic soils amended by many years of topdressing with sand. The North Course greens were rebuilt by Robert Trent Jones in 1969, seeded with Penncross bentgrass, and have soils with a high percentage of sand. The North greens have good internal drainage.

Annual Bluegrass is a prolific seed producer and with the ability to survive in hostile environments, can quickly establish itself in greens, tees and fairways. A small plant can produce up to 100 seeds. These seeds can germinate rapidly and with the ability to survive under very close mowing heights, can overtake a green surface in a few years.

Once established, it is extremely difficult to control and still maintain quality putting surfaces. Some herbicides are available to eliminate annual bluegrass .... but with large areas of bare turf on putting greens, the superintendent is often eliminated as well and therefore we choose not to use herbicides.

Herbicides: Spring vs. Fall

Most of us want to kill weeds like dandelions when they are most visible: in the spring. Spring flowering weeds are visible because ... they are flowering. That tells us that the plant is in a reproductive cycle, using available energy to produce flowers and seeds for new plants.

Most of the flow of water and food within the plant goes upward to sustain the production of these flowers. So it follows then, that a larger percentage of the herbicide we apply in the spring also goes upward and not down to the root. That's why the flower head wilts long before any leaves show signs of damage.

It is much more efficient to apply broadleaf herbicides in the fall, when the plant is translocating water and nutrients (along with the herbicide) down to the root system in order to get ready for a long dormant season. This is particularly relevant for perennial weeds like dandelions.

While we do make some herbicide applications in the spring, it is mostly cosmetic. Our most efficient use of resources is to make these applications in October, when we get a much better "kill ratio" on perennial weeds by attacking the root systems.

Frost

Frost is basically frozen dew that has crystallized on the grass, making it hard and brittle. A grass blade is actually 90 percent water, therefore it also freezes. Because of the short mowing height (sometimes as low as 1/8 inch) and fragile nature of the turf, putting greens are most affected by frost. Walking on frost-covered greens causes the plant to break and cell walls to rupture, thereby losing its ability to function normally. When the membrane is broken, much like an egg, it cannot be put back together.




Golfers who ignore frost delays will not see immediate damage. The proof generally comes 48-72 hours later as the plant leaves turn brown and die. The result is a thinning of the putting surface and a weakening of the plant. The greens in turn become more susceptible to disease and weeds. While it may not appear to be much of an issue if a foursome begins play early on frost covered greens, consider the number of footprints that may occur on any given hole by one person is approximately 60. Multiply that by 18 holes with an average of 200 rounds per day and the result is 216,000 footprints on greens in a day or 6,480,000 in a month.

Benefits of Aerification

As if we needed to cover this further ... here is a photo of #1 green South Course. You can see the longer, greener tufts of turf in the aerification holes from last fall. Not only does aerification help with growing conditions in the summer, it also helps turf withstand the difficulties of winter. More air and water helps the turf when it comes out of winter dormancy.