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Turfgrass Response to Mowing Pt. 2

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Recently, we discussed the impacts mowing can have on your grass. While it is necessary for a well-maintained lawn, we must consider its impact. A key question is… what length should I keep my grass?

The lower you maintain your grass, the higher the maintenance requirements. Shorter roots of low maintained grass are affected more rapidly by high heat. Low maintained grass must be mowed more often than higher maintained grass. Using the one-third rule, never remove more than one-third of the grass at a time.

 How Much Blade Length Should Be Cut at a Time

The general rule for mowing is to never remove more than one-third of the total blade length at a time. To remove more causes more stress on the plant.

For example, if you are maintaining your Bermudagrass lawn at 1.5″, you will be cutting the grass again when it puts on only half an inch of growth. If your Bermudagrass is maintained at 1-inch, then only one-third of an inch of growth puts you back on the mower. When the grass is actively growing the mowing frequency may be every few days for grass maintained at 1-inch or every week for higher maintained grass. Compare this to golf greens which are mowed daily. 

What about pastures or low maintenance fields? Since you may be only cutting the grass as hay on pastures and then letting it grow back to its longest reach before cutting again, the grass will remain the same thickness.

 Why the One-Third Rule

The goal is to do the least amount of harm. Removing only a third of the grass blade at a time helps keep all the functions of the plant operating efficiently. If you maintain your grass at 2-inches but wait until it reaches 5-inches before mowing, you are removing well over half the blade. Remember, the first inch of grass above the soil surface is the crown identified as white in color. From the crown, grass blades grow upward and roots grow down into the soil. The action of cutting off too much tissue shocks the grass and this occurs at the expense of the roots. Root growth may stop all growth for a considerable time if too much of the blade is cut. If a drought sets in or a heat wave, your grass may suffer. 

I used to maintain my father-in-law’s grass for him. He would always insist that I mow it very low so it will take longer to grow back so less mowing is required. I am sure his intention was for me to do less work. I would tell him it is not healthy for the grass and I would just mow it more often. I have found over the years that many people think the same way. If this is your habit of mowing, what is happening is the grass puts all its energy into regrowing long blades and it never thickens. You eventually end up with a very weedy lawn and your grass is of very poor quality.

 Meaning of Scalping

Most people consider scalping as cutting too low exposing the white color of the grass crown. Most of the time the grass will recover, but may suffer if this is repeated too often. The definition of scalping is not only removing grass to the soil level, but includes removing too much tissue that causes an undesirable effect. An example is removing 4″ of grass blade length to bring it back to a 2″ height in a single cutting. This can still be considered scalping. As stated, it can shock the grass and force it to use stored nutrients to recover. The grass must then be forced to produce enough carbohydrates through photosynthesis alone to keep up with daily functions since its reserves may be partially depleted. 

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 How to Mow Overgrown Grass

If your goal is to take over-grown grass and bring it back to the proper height, this is one way to do it. Start by only cutting off a third of the blade length at a time. Wait for a few days and cut again only removing a third at a time until it reaches the desired height. In between mowings make sure you are irrigating as needed and paying close attention to the appearance of the grass. If there is a problem then halt the mowing until you investigate the cause. You should make sure your blades are sharp to shorten the healing time.

This idea of watching grass appearance is important. Most turf managers who regularly maintain at lower heights know grass is more stressed than higher maintained grass. The grass appearance after mowing, along with the grass color, weather, moisture and other factors affect the grass more quickly. The lowest maintained grass, which are golf greens for example, have short roots that can overheat so heat is a concern. The grass temperature is often taken (literally) and syringing with water is often performed to keep it cool. Diseases are more common on lower maintained grass. Daily mowing, heat stress, spoon feeding nutrients and disease occurrence are some reasons why Bentgrass is considered such a high maintenance grass.

 Exceptions to the Rule

Perennial Ryegrass: P. Ryegrass has proven to be, in some regards, an amazing grass. As a stand alone grass, its primary range is in the Transition Zone. But, it is the best grass in the south for growing in dormant Bermudagrass and on Bermudagrass golf greens.

You may be wondering how Perennial Ryegrass can be used on golf greens since they are maintained so low. Bermudagrass greens, like other varieties of Bermudagrass, go dormant and turn brown in the winter. In the summer months these greens can be mowed daily at 1/4″.  Perennial Ryegrass that is overseeded on greens in winter can be mowed at 1/2″ without harm to the grass (Dr. Nick Christians, Fundamentals of Turfgrass Management). 

Researchers do not know exactly why Perennial Ryegrass survives this low mowing, but it is the only one that can be used in this way. In the spring, even lower mowing to 1/3″or 1/4″ helps to remove the Perennial Ryegrass and the Bermudagrass greens take over again. 

Centipede Grass: Centipede grass starts to decline if not mowed. It thrives when it is maintained at lower heights. Mowing heights are from 1″ to 2″ (be sure to read your variety specifications) and if maintained higher this can lead to diminished quality.

 How Turf Formula® and SuperCal® Help

Turf Formula®and SuperCal® work together to make your soil better for plant growth. Aside from a natural increase in nutrients, disease pathogens are lowered. University of Missouri/Columbia found that 35% of Brown Patch Pathogens were reduced in 24-hours. Many of the soil microbes, such as protozoa, feed upon pathogenic microbes that infect plants. Pathogenic microbes can reach a threshold where disease pressure reaches the point of infection, but using Turf Formula® can help keep them under control.

This duo is sure to make a difference and improve your turf this growing year.

Russ James
AgriGro Turf Specialist

Question? Contact us. 




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Overseeding Bermudagrass with Perennial Ryegrass

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 The Science of Overseeding Bermudagrass with Perennial Ryegrass

One of the highest performing grass species is bermudagrass. With over  50 actively grown varieties around the world, bermudagrass is a favorite in hot, sunny locations from home lawns, fairways, even golf greens. All varieties of Bermudagrass can excel in the sun and heat where other grass types fail. The number of months it stays actively growing is determined by where in the country it is planted. Bermudagrass has a wide growth range that extends from the deep south to the top of the Transition Zone.

In Southern states, the DOT (Department of Transportation) plants bermudagrass along roadsides since it is a low maintenance turf that does extremely well, even in hot, dry locations. Mowing is performed as the only maintenance. However, on the high end of the spectrum, high maintenance sports turf with improved or hybrid varieties have been used due to their beauty and ability to endure heavy traffic.

 Bermudagrass Behavior

Like most warm-season grasses, as winter approaches and soil temperatures drop, bermudagrass goes dormant. In the northern reaches of its range, the active growing time may be no more than half the year.  The tan-colored dormant grass will remain unchanged until spring when the weather and soil temperatures warm again. The problem is that dormant bermudagrass does not provide a quality playing surface for golf or on sports fields. To fix the problem, some sports turf managers will begin overseeding the dormant grass with Ryegrass. 

Of all the species of warm-season grass, only bermudagrass can survive unharmed when overseeded in the fall. Overseeded bermudagrass allows for a better appearance and play on golf courses and better turf quality for team sports than playing on dormant bermudagrass alone. Bermudagrass is the primary grass here and it is the one that a turf manager is primarily concerned about. The overseeded grass, while well cared for, is always temporary but needed.

 Seed of Choice for Overseeding

The grass of choice for overseeding was Annual Ryegrass in years past. However, the current choice is Perennial Ryegrass. Dormant bermudagrass can easily revive after a winter of fertilization, irrigation, and other maintenance requirements needed to maintain the ryegrass. The same winter treatment can weaken or injure centipede, zoysia, or other warm-weather species. It has become a common practice for many golf courses and even some homeowners to overseed the bermudagrass in the fall with perennial ryegrass or annual ryegrass to provide a green color in winter.

 Why Perennial Ryegrass is Preferred

You may wonder why Perennial Ryegrass is preferred, especially since it is a perennial and not an annual. Perennial Ryegrass is used as a stand-alone year-round grass but is mostly restricted to the transition zone. It can’t handle the high heat of the southern summers or the extreme winter cold of the most northern states. It is used in the south as a winter grass. 

To be fair, in years past, annual ryegrass was used on sports fields and golf courses, but the problem was annual ryegrass (i.e. Italian ryegrass) was not as developed as a turfgrass. It didn’t possess the qualities needed to make a fine home turf or sports turf. Sports managers moved to Perennial Ryegrass due to its better turfgrass qualities. Managers had to factor in the grass being a perennial and how it would increase the time and effort in maintaining and removing it. The payoff was how Perennial Ryegrass was undeniably better in every way. Compared to Annual Ryegrass, Perennial Ryegrass is a much darker green and is less coarse than Annual Ryegrass. Plus it can endure traffic better, grows quicker, and will last longer into the spring. Annual Ryegrass often begins to die back before the manager desires it to, leaving behind a less than desirable lawn full of clumps of pale and dying grass and a lower quality playing surface. While Perennial Ryegrass is not an annual grass, in this case, it is being managed as an annual.

In many areas of the country, Annual Ryegrass is still what is planted, especially by non-professionals. It doesn’t require the knowledge of turf management compared to Perennial Ryegrass.  In southeast Texas, I did a search of all the farm and landscape stores in a 20-mile radius and most of them had Annual Ryegrass. In fact, I found it was the only cool-season grass any store sold. While planting Annual Rye is far easier, it can’t come close to the beauty or quality of Perennial Ryegrass.

While planting Perennial Ryegrass will provide a much better quality turf, it also requires more skill and knowledge of both bermudagrass and Perennial  Ryegrass growth habits. Turf managers understand the goal is to encourage the bermudagrass to recover in the spring while at the same time ensuring the Perennial Ryegrass is dying back. The window is short and timing is crucial. Southern states use a combination of cultural practices and specialized herbicides at just the right time that will eliminate the ryegrass without harm to the bermudagrass just as the bermudagrass is recovering from dormancy. Northern states most often use specialized herbicide almost exclusively.

 It Begins in the Fall

In the fall as Bermudagrass is transitioning from growth to dormancy is the time to overseed with a Perennial Ryegrass variety that grows best in your area. There are currently about 120 varieties being tested or grown as turfgrass.

The rate of seed spread recommended for golf courses is approximately 12-lbs per 1000-sq. ft. over thick, dormant bermudagrass. Determine the correct amount between 12-lbs and 15-lbs for thin bermudagrass or where bermudagrass and shade meet.

You will need to water the seeds lightly two to three times each day until it germinates. Keep in mind you are not watering the grass, but are just putting enough water down to keep the seeds moist. Ryegrass is a quickly germinating seed that can sprout as soon as 3-days after planting.

Every grass species has a temperature range and conditions in which it is said to reach maximum growth potential. For most cool-season grasses, the best growth temperature is 60 to 75-degrees. For warm season grasses, it is 85 to 95-degrees.

 When to Plant is Crucial

The timing of planting the seed is just as crucial as removing it. Planting ryegrass too early before dormancy is setting in or removing it too late in spring can cause serious harm to bermudagrass. If the Ryegrass is allowed to stay too long after bermudagrass should be greening up, you are risking injury because the ryegrass will shade the bermudagrass. Some managers will delay killing the ryegrass because in the spring it looks so good. But bermudagrass is the primary grass. Bermudagrass injury can start where the full sun is reduced by as little as 30-percent.

Here is one of the dilemmas that must be addressed. Emerging bermudagrass from dormancy to full recovery is a slow process. It can take as long as 120-days from emergence to full recovery. In Missouri, there are about 6 to 7-months of growth from emergence, dormancy, to full recovery and back to dormancy again. It depends a lot on how long into the spring the winter fights to stay around. Lately, that has been as late as May. Plus, the temperature when bermudagrass is emerging from dormancy is also the best temperature for ryegrass growth.

 On Southern Turf

To help bermudagrass recover favorably in southern lawns, golf courses, and sports fields, just before emergence, managers perform low mowing below the height which is healthy for Perennial Ryegrass. You are performing practices that favor the bermudagrass over the Perennial Ryegrass and allow light to reach the bermudagrass. As standard cultural practices on golf courses for removing Perennial Ryegrass, you can perform vertical slicing to encourage bermudagrass growth, add Ammonium Nitrate at high rates to help burn the ryegrass, core aerate for increased bermudagrass root growth by allowing water and air increased access to the roots, and irrigate as needed.

Some Perennial Ryegrass varieties are more tolerant of cultural practices alone and not all will die back. If this is the case you will need to use specific herbicides that kill ryegrass without harm to bermudagrass.

 Use Herbicides for Controlling Ryegrass

Herbicides that kill Perennial Ryegrass are favored over cultural practices in northern locations. This is because the bermudagrass growth season is much shorter. The time allowed for full recovery must be completed before the end of the season or your bermudagrass will decline each year. Removing Perennial Ryegrass quickly is favored over cultural practices alone since the temperatures that favor ryegrass last much longer into the spring and the temperature that favors bermudagrass is equally short.

For chemical control of Perennial Ryegrass, there are several products that have been tested and used regularly.  We will only look at three of them, but there are around half a dozen more. The tests found that of all the products that are labeled for removing ryegrass, some worked faster than others and some were more effective at removing ryegrass than others.

Kerb SC T&O Herbicide
Kerb SC T&O by Dow Agrosciences had the best results. It carries a “Caution Label” and is somewhat expensive. Two-and-a-half gallons can retail around $800. It is for use on all grass locations except home lawns (non-residential use).

Monument Herbicide 75WG
Among the top performers was Monument Herbicide 75WG. It is for professionals and sod farmers due to the way it must be sprayed. Your tank must have constant agitation from the moment it is mixed and continues even when not spraying at the time. The equipment in the label description is large equipment that is not generally used by homeowners. It comes in small boxes with packets of 5-grams each. The packet itself is dissolvable in water so you never touch the chemical.

Revolver Herbicide
This one is the most versatile herbicides for homeowners, sports fields, or commercial sites. It can be used on lawns or sports turf and can be mixed in containers as small as a gallon pump tank. It can remove most all cool-season grasses grown in warm-season grasses. It can also be used safely on bermudagrass, zoysiagrass, and buffalograss as a spot treatment only.

The cost of Revolver is less than $300 for a quart.

Read the entire label before using it. It is the law and regulates where and how it can be used, stored and the PPE that must be worn.

 How Turf Formula® and SuperCal® Help Create Beautiful Turf

AgriGro Turf Formula® increases germination rates as well as adding nutrients, enzymes, amino acids, and more that plants need. Studies show photosynthesis and the production of carbohydrates were more efficient after using Turf Formula®.

In university studies, Turf Formula® increased the beneficial microbes by 3400% in just 24 hours and by 5000% in 72 hours. This explosion of beneficial microbes breaks down soil elements into nutrients quickly. Microbes themselves add to the soil many elements needed for healthy plants.

In addition, plant pathogenic microbes were reduced by 35% in university studies performed by the University of Missouri/Columbia. Many beneficial microbes, including certain protozoa, feed only on pathogenic or harmful bacteria.

SuperCal® was added to Turf Formula® when tests were done. Microbes need calcium to achieve their highest activity. SuperCal® is over 40,000 times more soluble than lime. It is immediately available for plants to use. Calcium strengthens the plant cuticle (surface thickness) making it more resistant to diseases that enter via plant surfaces. Calcium is needed for photosynthesis, root development, and necessary for the transport of nutrients.

In lab studies, macro and micro-nutrients were naturally increased due to the action of soil microorganisms with the exception of soil salts. Too much salt can harm the structure of healthy soil. Turf Formula® helps reduce soil sodium levels. Golf superintendents have been able to reduce the inputs of nutrients via fertilizers by 35% due to the microbial action that converts soil elements into available nutrients. Order Turf Formula® and SuperCal® today.

Russ James
AgriGro Turf Specialist

Question? Contact us. 




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Turfgrass Response to Mowing Pt. 1

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Mowing your lawn is the most often applied cultural practice performed on grass. It is necessary for a well-maintained lawn, professional landscapes, and sports fields. A beautiful lawn with rich green grass is easy on the eyes, adds curb appeal, and is a pleasure to play on. What is not often considered is how grass responds to mowing. However, a key understanding in professional turf management is knowing that mowing is merely tolerated by grass and as a result has specific reactions to it. What this means is that mowing is followed by predictable responses in the blades and roots.

We will cover the key responses to mowing and how you can use these to your advantage.

 Mowing is Always Stressful to Grass

Many people see mowing as something similar to getting a haircut – as something that causes no harm and usually looks great for a while. But, it’s actually the complete opposite with grass. Grass blades are filled with Chlorophyll that is used as the means of producing carbohydrates through photosynthesis. These carbohydrates are consumed by the plant as energy to keep all plant functions operating efficiently. Longer blades have more surface area and more chlorophyll to absorb light for photosynthesis. When grass is mowed, you are removing a portion of the blade that is necessary for photosynthesis and as a result the plant stresses. This stress triggers several different plant responses.

In addition to removing a portion of the grass blade, the blade’s cuticle (the hard, waxy surface) is cut by the mower blades creating an injury that must heal. Sharp blades create less of an injury than dull blades. The cuticle is important because it creates a barrier that protects the internal tissues of the blade.

Healthy plants have thicker, stronger cuticles that help resist certain pathogenic fungi that enter the blade via penetration through the cuticle. Mowing the grass offers a location for a pathogen to enter without having to penetrate the cuticle. Reel mowers cut like scissors and leave behind a smooth edge that heals very quickly. When you see brown and shredded grass ends, this is a sign that your blades need sharpening. These larger injuries created by dull blades heal more slowly and offer an even broader area for diseases to potentially enter.

 The Good News

Don’t lose heart, however. Fortunately, of all of the different plant species, grass is among the most tolerant, especially when it comes to mowing or grazing by most animals. Grass can handle a great amount of abuse and still look good. This is due to the fact that the growing point of grass is close to the soil’s surface and the grass can easily produce additional tissue in response to mowing. Still, there are things that you can do to weaken the health of the plant and in most cases, you will want to avoid these, if possible…

 Understanding How Mowing Effects Grass: Considerations Before Mowing

Before mowing, you should consider that every grass type has a “lowest mowing height recommendation.” This means if you mow lower than what is recommended for that grass variety it can start to weaken the grass, which leads to thinning and even die back.

 The Rule of Mowing and Root Length

As a standard rule in mowing, the lower the mowing height, the shorter the root growth. Taller maintained grass of the same species will have longer, farther-reaching roots than if mowed at a lower height. Why is this?

First Predictable Consequence to Mowing:

Let’s take Turf Type Tall Fescue (TTTF), for example. Mowing comes with predictable responses with this grass species. Most fescue grass turf varieties can be maintained from 1.5-inches to 4-inches. If left unmowed, most turf-type tall fescue grass will only reach up to 10″ or more in height. That is about 9-inches of blade length for photosynthesis.

However, if you maintain your grass at 2-inches, that length is not long enough for photosynthesis to meet all the plant’s needs. Therefore, in response to the low mowing, the grass will put out more tillers (stems and grass blades) that will develop below the cutting height to compensate for the loss of tissue. In this way the shorter grass will actually be thicker, having more blades to absorb sunlight to compensate for the lower mowing so it can effectively carry out the necessary photosynthesis. For this to happen you will consistently need to mow before the grass puts on another inch in height. Golf courses often utilize this because a thicker playing field is better for the ball. But this lower mowing height requires a higher level of maintenance.

Second Predictable Consequence to Mowing:

In order for the grass to produce twice as many blades due to consistent low mowing, it must redirect energy that would normally go somewhere else. For grass, it redirects from the roots. The grass redirects energy from the roots to the blades where it will consume this energy to produce even more blades. In contrast, the higher maintained fescue is somewhat less thick with the longer blade length but has a deeper and farther-reaching root system.

Note: There is a direct link between root depth and mowing height. Low mowing produces shorter roots where deep roots are a byproduct of higher maintained grass.

Using this to Your Advantage

Depending on where you live in the country, how tall you maintain your grass can be important. If you have frequent summer droughts or even long stretches of hot weather, like California, maintaining your grass at 4-inches will send down deeper roots than lower maintained grass. This root depth will help the grass survive the heat and drought. This also depends on how you follow correct irrigation methods of deep watering (at least 4-inches of moisture reaching down into the soil)  followed by no irrigation until the grass shows signs of needing it again.

 How Turf Formula® and SuperCal® Help

Life begins in the soil. Turf Formula® adds enzymes, plant hormones, and nutrients needed for plant growth. This cutting-edge technology when added to the soil multiplies the natural beneficial microbes by 5000% in 48 to 72 hours. This is an incredible explosion of beneficial microbes that break down natural soil elements into nutrients that plants can immediately use. Improved water and nutrient uptake and more efficient photosynthesis help relieve stress in grass. Plus, Turf Formula® can double the root mass of turfgrass. This is important for all grass species, but especially on low cut turf.

SuperCal® is an immediately available source of calcium that is necessary for plant function. While lime also has calcium, it is a poor source of calcium that takes a couple of years to break down and rarely works more than an inch into the soil on turf or pastures. 

SuperCal® is more than 40,000 times more soluble than calcium in lime and binds with the soil’s CEC sites where it is available when the plants need it. Best of all, it builds the calcium saturation levels in your soil. Check it out for yourself today!

Russ James
AgriGro Turf Specialist

Question? Contact us. 




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