Design and Installing Lawn Irrigation Not As Easy As It Looks

Q. We installed a lawn 18 months ago, but it has a difficult time during summer months. I aerate it, fertilize it and I know the drainage is good because the landscaper installed the system to our HOA requirements. I water twice daily, six days a week around 5 AM and 9 PM. There is a decent amount of shade and the yard faces south. Even the heavily shaded areas have problems. What can I do differently?

Brown patches in lawns during hot summers will quickly show irrigation weaknesses. Notice these patches are also close to the patio where people walk. This area should probably be core aerified annually due to traffic.

A. I looked at your pictures and the lawn looks good in most places except for a few small brown areas. Brown spots during summer months frequently point out weaknesses in the irrigation system. In your case the brown spots are also in front of the patio where there is alot of human traffic. Areas like this should be core aerified annually.

Hollow tine aerifier

            My first suspicion is the irrigation system and was not installed or maintained properly. Let’s cover the basic “must dos” when installing and maintaining an irrigation system.

Water pressure

The operating water pressure MUST be within the operating range of the sprinkler nozzles. Frequently this is 15– 30 psi. Some expensive sprinkler heads have built in pressure regulators, but lesser expensive ones may not. If the water pressure is too high, fogging or misting will occur out of the nozzle. If the sprinkler head is “fogging”, then brown spots will occur in weak areas. If pressure is too high, reduce it with a pressure regulator. If water pressure is too low, remove any pressure regulator, change it for the proper one or install a booster pump to increase the water pressure.

Head to head coverage

Water must be thrown from the nozzle far enough to reach neighboring sprinkler heads. Sprinkler heads must be installed at distances specified by the nozzles. These distances are meaningless if you don’t have the right water pressure.

Sprinkler nozzles

Sprinkler nozzles specify the operating pressure range, allowable spacing between sprinkler heads and precipitation rate in inches per hour among other things. These nozzles must be matched to each other. If someone maintains the irrigation system and replaces a nozzle with the wrong kind, it will produce brown spots in underwatered, weak areas.

            Curved areas and re-curved areas of the lawn are the most difficult to water. There are adjustable nozzles that can be used but it will always be a weak irrigation area subject to brown spots.

•             Never water early at night like at 9 PM. If your lawn is healthy and it has a good irrigation system, one irrigation per day during summer is all that most lawns need IF the sprinkler system was designed and installed correctly. Irrigation should finish just before dawn. If you must water late in the day, apply water so that the grass leaf blades dry before it gets dark.
•             Don’t rake or catch the grass clippings when mowing. Most mowers now are “mulching mowers” with a special blade and deck design. Returning the clippings to the lawn substitutes for one fertilizer application each season.

Brown Spots in Lawn Probably "Frogeye" Disease

Q. I have some large dead areas in my lawn. I don’t think it’s an insect problem. Watering is at 2 AM and 7 AM. This was my first lawn problem in 16 years!

Unusual pattern for dead grass. Too random for irrigation I think.

This picture you start to see the "frogeye" disease pattern. Looks like it could be a chemical spill.

Here is where "frogeye" starts to make an impression. But its over. 

A. I looked at the pictures you sent, but the last picture was the most “telling” to me. I think your lawn had a disease problem that is now finished. Don’t do anything now! Let me tell you why I came to that conclusion.

            Insect problems here are not like those “rolling back like a carpet” problems described in books and online. Those descriptions apply to Kentucky bluegrass damaged by white grubs. We have grubs, but we don’t have much bluegrass anymore. Our lawns are 95% tall fescue and tall fescue reacts differently to insect damage. It pulls out like loose hair from an old animal skin. Plus, the pattern of dying grass does not resemble insect damage.

Rolls Back Like a Carpet

            I first thought the brown spots were an irrigation problem, but the pattern doesn't fit an irrigation problem. With irrigation problems, dead or damaged areas are in a pattern that relates to the location of sprinkler heads. I didn’t know where the sprinkler heads were, but the damage was irregular, so I ruled out irrigation.

Irrigation problems are nearly always easy to see how they connect to the sprinklers.

            The pattern does, however, resemble a chemical spill flowing downhill and damaging the grass in its path. It was a possibility, but the last picture looked like advanced stages of a disease problem. We used to call this disease Fusarium blight or “frogeye”. This disease has since been renamed Necrotic Ring Spot. I thought “frogeye” was much more descriptive.

Seldom will you see it this obvious but this is frogeye. See how it got its name? In advanced stages these dead areas can become one but you still look for little patches of green grass that would still be there. Sometimes its hard to see them.

            What led me in the direction toward disease were the small patches of green grass still alive but surrounded by dead grass. These small green patches of grass are how “frogeye”, now Necrotic Ring Spot, got its name.

            From the pictures, it looks like the disease has run its course and the grass that’s alive is healthy. I say this because the grass surrounding the dead areas appears healthy. This is the way lawn diseases usually work. They have a window of opportunity, when the weather is right for the disease to spread, and it takes off. The weather changes and the disease stops.

            You would be wasting your money to apply a fungicide now that it’s over. But, don’t disturb the brown, dead grass and leave it alone until fall. If you remove it now, it opens the soil to invasion by Bermudagrass. Bermudagrass loves sunshine, bare soil and water. It hates shade. Wait until the weather cools in late September or October, remove the dead grass and either seed or sod these areas.

When to Fertilize Lawns

Q. When is it time to start fertilizing lawns again?

Lawns can be beautiful but they need regular feeding. The light green color of this lawn is an indicator it needs an application of nitrogen fertilizer. That nitrogen fertilizer will turn that light green lawn into a dark green lawn in a matter of a couple days.

A. It depends on whether the lawn is fescue, only Bermudagrass or Bermudagrass overseeded in Fall to maintain green winter color. Fescue lawns and overseeded Bermudagrass lawns are fertilized the same during winter months.

Ammonium sulfate fertilizer contains only nitrogen that the plants need when their color is not dark enough. The sulfur in the sulfate is also important for plants but in the case of light green color, all that's lacking is nitrogen.3 to 5 pounds of this fertilizer spread evenly over 1000 ft.² of lawn and watered in will turn the color a deep green instead of light green.

            Fescue and overseeded Bermudagrass should have been fertilized last Thanksgiving to maintain dark green color through winter. If this fertilizer application was missed and temperatures get cold, the lawn can turn brown when it gets very cold or just light green if it does not.

            The next fertilizer application to fescue lawns would be when air temperatures enter the 60s. Fertilize Bermudagrass that was not overseeded when temperatures enter the 80s.

Once or twice a year add a better quality fertilizer to the lawn like this one. It has a little bit of phosphorus, the middle number. Lawns don't need a lot of phosphorus because we don't grow them for their flowers and fruit. I would like to see the potassium, the last number, higher than this but this is a good lawn fertilizer.

            Established lawns require fertilizers containing high nitrogen, and occasionally an application of iron, for dark green color. However, they will perform best if this fertilizer contains also low levels of phosphorus and moderate to high levels of potassium.

            For this reason, fertilizers similar to 21-7-14 or 10-5-10 are frequently recommended for lawns. Some people use only high nitrogen fertilizer such as 21-0-0 and omit phosphorus and potassium.

            I think this is a mistake and a good lawn fertilizer should be applied at least once during the growing season. Instead, experiment and try fertilizing with only half the amount of fertilizer recommended on the bag. This is all that is usually needed if you are not bagging lawn clippings but mulching them back into the lawn using the mower.

Are Organic Fertilizers Really Organic?

The organic movement has a foothold in the turfgrass and ornamental industry. The same industry brewing for decades in home vegetable gardens, and then with small-scale producers, has emerged as a significant market percentage for commercial landscapers. Homeowners are asking for “organic” landscape plants, organic methods of controlling pests and applications of “organic” fertilizer to their landscapes.

Migration of Organics to the Landscape Industry

            Alternative methods for producing and maintaining ornamentals and turfgrass have been around for a long, long time. In the past, very few residential clients were willing to pay for the additional costa associated with the product. That may be changing thanks to local food movements and organic agriculture¹. The word “organic” has become synonymous with “wholesome” and “safe”.

Organic fertilizers for vegetable gardens

            Organic has a different meaning in landscape horticulture industry. Organic can mean sources that are not synthetic or conventional. Organic amendments, such as municipal and animal sources of biosolids, can be applied to improve soil physical and chemical properties which in turn can improve turfgrass establishment rates, growth, and quality. We know, for instance, that in poor or marginal soils the incorporation of compost improves soil properties, increases soil nutrients and consequently improves plant growth. In soils with a naturally higher percentage of organic matter these improvements are less noticeable.

Nitroform urea used in the landscape industry could be classified as an "organic" fertilizer even though it is manufactured

 Composted Dairy Manure Reduced Turfgrass Disease in Colorado

            Research at Colorado State University evaluated the effects of applying composted dairy manure as topdressing to Kentucky bluegrass. Researchers applied compost at the rates of 13.3, 26.6 and 40 cubic yards to the acre. Applying composted manure as topdressing to established bluegrass in 2003 through 2004 improved the soil’s physical properties and nutrient content.

EZ Green Is a composted chicken manure product for the landscape industry that is OMRI listed product for the organic program by USDA

            Although nothing new, the application rates are important. The two higher rates improved turfgrass overall quality and allowed the grass to retain color in the fall, early winter and green up faster in the spring. Not bad for a product that is not considered a fertilizer.

            During the hot summer months the two higher application rates produced about 50% more clippings. The researchers concluded that compost improves turf quality and shoot growth via its action as a slow-release fertilizer.

Lawn clippings remove from the grass and left on the curbside for dumping in landfills. These clippings are filled with valuable nutrients that could be returned to the lawn resulting in one less fertilizer application each year.

            More turfgrass clippings sound like a potential landscaper’s nightmare but there is a positive side to this “problem”.  Increased amounts of clippings in summer months helps suppress the incidence of hot weather diseases. Infected leaf blades are removed through regular mowing and mulched back into the turfgrass sward or removed from the property.

            Disease suppression by composts, composted biosolids and compost teas in vegetable crops has been documented fairly well. But research has been conducted on the suppressive effects of composts, such as biosolids, on turfgrass diseases as well, dating back 20 years or more.

Compost tea applicator used for soil applications

            This research shows promise to “organic” gardeners by reducing the application of fungicides, synthetic fertilizers and other chemicals to home lawns. Composts show promise in controlling turf diseases such as Pythium, summer patch, brown spot, dollar spot, red thread, necrotic ring spot and others.  Reductions in the applications of pesticides such as fungicides, directly supports the “organic” movement whether it is truly organic or not.

Lawn clippings from commercial properties represent a huge amount of fertilizer that is removed from the lawn grasses and buried in landfills.

Composted Biosolids Benefits To Landscapes Shown by Texas Researchers

            Researchers at Texas A and M University, from 2005 through 2008, demonstrated the benefits from composts used for soil improvement and nutrient enrichment can be transferred from the sod farm to newly established landscapes. Previous studies with sod that recycled manure-based soil amendments as topdressing indicates that 77% of the phosphorus and 47% of the nitrogen might be removed and transported in a single sod harvest.

            About one quarter of the cubic yard of composted biosolids was incorporated to rootzone depth in a cubic yard of native soil when establishing Tifway bermudagrass sod. Researchers measured that five times more nitrogen and seven times more phosphorus was available to turfgrass grown in biosolids compared to grass grown without biosolids.

Fertilizer content of composted biosolid product by a local Las Vegas supplier

            After two sod harvests, all of the nitrogen and phosphorus applied from the biosolids was removed with the sod. These nutrients were transferred, with the sod, to the landscape.

            Although not demonstrated, researchers claimed that this could result in faster establishment times and better turfgrass cover in a shorter period of time. This, of course, would reduce the amount of fertilizers needed during sod establishment. Another coup for the organic movement.

            They also found that sod established with biosolids was lighter in weight than sod grown without biosolids. Biosolids-grown sod contained more water but less native soil than sod without biosolids. This helped preserve the native soil. Less fuel is needed for transporting the sod. Organics, are you listening?

Composts Release Fertilizer Nutrients Slowly

            Composts, when used as a fertilizer, releases nutrients slowly, acting like a slow-release fertilizer. When establishing turfgrass in sod farm operations, rapid turfgrass establishment is important so a rapid release of nutrients, particularly nitrogen, is needed.

            This was not going to happen with compost-amended soils. So the researchers applied either 50 or 100 pounds of nitrogen per acre at the time of sprigging (establishment) to supplement the slowly-released nutrients contained in the compost.

            Because of the application of supplemental nitrogen, the time between harvests in biosolids-amended soil plus fertilizer was reduced 60% compared to the time needed for sod grown with biosolids only.

            Similarly, other researchers reported better turf coverage and density when a two to three inch depth of compost was incorporated to a 6 inch soil depth compared to soil without compost. They attributed these responses to improvements in the soil’s physical properties such as better pore spaces, greater rooting depth and improved drainage.

Applying Too Much Compost Two Landscapes Can Be a Bad Thing

            Composts can be over-applied to landscapes. This can become a serious environmental concern to surface waters such as irrigation ponds and waterways. When composts high in nutrients such as nitrogen are applied to turfgrass as topdressing, researchers have found a significant amount of nitrogen can be transported to these waterways.

            Incorporation of composts to a greater depth should reduce the amount of nutrients removed compared with topdressing. Incorporation of composts to greater depths should allow for less frequent applications as well which would save money. In addition, soil incorporation of biosolids should reduce the potential for runoff of nutrients after establishing in urban landscapes.

¹USDA “trademarked” the term “organic” into its National Organic Program in The Organic Foods Production Act of 1990. This federal act required USDA to develop national standards for organic products and was codified in 2000 (Code of Federal Regulations at 7 C.F.R. 205). So far, it has only been applied to food crops. http://www.ams.usda.gov/AMSv1.0/nop

Bermudagrass Lawn Change of Color May Be Drought

Q. We have lived in the same house in Las Vegas for the last 42 years and every June my lawn has the same problem. The lawn is a mix of common and hybrid Bermudagrass. First the grass turns grayish (in patches) and then it turns brown. It slowly comes back by September. I water according to local recommendations, use Scott's Turf builder 3 to 4 times a year and use Ortho Bug-B-Gone insect granules twice a year.
 

A. If this were tall fescue I might be tempted to say this is a disease problem. However, since it is a mixture of Bermudagrasses I think this is an irrigation problem. This will be particularly true if these problem areas are in the same locations every year.

Turfgrass or lawns will turn a smoky or grayish green when they are not getting enough water. This is because the leaf blade either folds in half or roles depending on the grass. This creates a different color; smoky or grayish green

            Bermudagrass in our climate doesn’t develop many insect or disease problems.

            The success of lawns in our desert climate is directly tied to the quality of an irrigation system. In technical terms we say the irrigation system should provide head to head coverage; water from a sprinkler head should be thrown far enough to reach the head to its right and it’s left. If we don’t provide this kind of uniformity in the design and installation of an irrigation system it can result in brown patches that don’t receive enough water.

A close-up of the grayish green color where the lawn is not getting enough water

            The water pressure in the sprinkler system should fall within a range recommended by the sprinkler manufacturer. If the water pressure is too high or too low it will affect the distribution of water and create browning of the lawn in the same areas year after year. Otherwise, there are sprinklers now that will lower the water pressure before the water is applied to the lawn.

Another indicator of drought or lack of water in a lawn are footprints. If you walk across grass that needs water, look behind you. If your footprints remain in the grass does not spring back quickly, the grass needs water.

            You can correct this problem in the short run by increasing the number of minutes that you apply water. This delivers more water to the dry areas. Unfortunately, it also delivers more water to the wet areas resulting in overwatering of the green areas.

            It is also a good idea to punch holes in the lawn with an aerating machine in the spring, particularly in the brown areas. This helps water to move into the soil and not run off into low spots if there are any.

            Bermudagrass is notorious for building up “thatch”. Thatch is a buildup of old grass stems and debris under the surface of the lawn but on top of the soil. Years ago this thatch was burned off of the lawn with fire. We can’t do that anymore. We must do it mechanically now.

A core aerifier for lawns pulls plugs or cores out of the lawn that are about 4 inches deep. This type of verification provides better drainage and water penetration for lawns suffering from drought

            It is important to dethatch Bermudagrass each year. This is usually done in the fall when overseeding it with a cool season grass like ryegrass to maintain a green winter lawn. If the lawn is not overseeded in the fall then thatch can be a huge problem in Bermudagrass.

D thatching machines, sometimes called vertical mowers, pull debris from a lawn which allows water to better penetrate the soil and reduces runoff.

            Making changes to the irrigation system will correct some of this problem and reduce the amount of water needed to keep the lawn green. Increasing the number of minutes you apply water during the heat of the summer should solve this problem in the short run.

            But I would combine this with lawn aerification every three or four years and dethatching every year to improve the amount of water entering the soil in the dry areas.