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Archive for the ‘Lawns’ Category

Written by Dr. Tony Koski, Extension Turf Specialist
Department of Horticulture and Landscape Architecture
http://csuturf.colostate.edu       http://csuhort.blogspot.com

Lawns that are covered by flood waters, even temporarily, may be subject to various types of damage. In general, most turf species will tolerate a few days of flooding without any negative effects. However, turf that remains flooded for more than a few days (especially when it is hot) can rapidly decline due to lack of oxygen and light. Substantial turf loss can be expected after 4 days of continued submersion. Other factors associated with flooding of turf include: soil coverage, water contaminated with petroleum or pesticides, high water temperature and algae scum. The most significant long-term effect of flooding is the deposit of sediment (“muck”), primarily silt and clay, over turf surfaces. This can lead to serious soil layering problems and even death of the existing grass.

Short-Term Care of Flooded Turf
Once flood waters have receded, pick up any debris, such as wood, glass, stones, nails and other metal objects deposited on lawn areas. This debris could pose a safety hazard to mower operators and damage power mowers or other equipment later used to maintain the lawn, as well as to people and pets who may use the lawn for recreation. Remove leaves or any other material that may smother grass.

Soil (“muck”) deposited on a lawn can sometimes be removed before drying by a combination of scooping/shoveling and washing with a jet of water using a hose-end sprayer.  However, removal of soil may be impractical or impossible due to the size of the lawn area, the depth of the soil, the weight of the wet soil, and ability to move it to another location.

Soil deposits on golf greens and other sand-based turf systems (soccer, football or baseball fields) should be removed as quickly and thoroughly as possible to reduce the potential for silt and clay to move into the sand root zone, clogging the pores and reducing infiltration and permeability. The use of shovels, sweepers and water to move/remove soil deposits will reduce the potential for damage. However, these affected turf systems will likely require aggressive core cultivation and topdressing to restore and maintain acceptable infiltration and aeration.

After the Turf has Dried
It is often not possible or practical to remove deposited soil from flooded turf while it is still wet. The drying process may take two or three weeks, perhaps longer, depending on weather, soil, and drainage characteristics of the underlying soil and turf. Remediation at this point is largely dependent upon the depth of deposited soil.

Lawn repair with less than 1-2 inches of soil
Lawns submerged less than 4 days and covered with an inch or less of soil have a good chance to recover.  Assessment of potential lawn damage and recovery may not be possible until those areas have dried. Checking for new shoots emerging from the soil or the emergence of new shoots from surviving plants is a good way to make an early assessment of damage. Usually, once regrowth has begun, it will continue, although it may take several weeks before the lawn has completely filled in.

Core cultivation/aerification is one of the most important and beneficial operations conducted where soil deposits are less than an inch. When the lawn has begun to grow (green leaves begin to appear), go over the lawn 3-4 times with a core type aerifier. This will help improve overall soil structure, improve soil oxygen levels, help break up soil layering problems caused by the deposited soil and encourage recovery during the fall. The lawn should also be fertilized (using any lawn fertilizer, following label instructions for applying the correct rate) at this time (September-October).

Overseeding can also be done at the time of aerification. The aerification holes provide perfect conditions for the germination of grass seed. Lawn areas that are thin (or the entire lawn can be overseeded at this time) can be overseeded with Kentucky bluegrass or a Kentucky bluegrass/perennial ryegrass mix (tall fescue lawns should be overseeded with tall fescue seed), using a seeding rate of 5-6 pounds of seed per 1000 square feet. Rake the lawn lightly after seeding to work seed into the aeration holes. Irrigate the lawn to maintain moist, but NOT saturated, soil conditions.

Lawn repair with greater than 2 inches of soil
Lawns covered with more than 2 inches of soil may be heavily damaged, with only a slight chance of recovery. Degree of recovery will vary with grass species and depth of soil. The greater the depth of soil, the slower the recovery and the less likely the lawn will recover. If the lawn area is completely buried with many (3 or more) inches of soil, then the best strategy may be to accept that the majority of the lawn has already been severely damaged or killed and it will be necessary to reestablish a “new” lawn.

Reestablishment of a “new” lawn over a flood-damaged lawn
To reduce the future potential for soil layering to cause drainage and rooting problems for the new lawn, there are two ways of dealing with the deposited soil. One is to remove as much of the soil as possible, down to the original lawn surface. Understanding that this may be difficult or impractical, the deposited soil may be left on the lawn and rototilled into the lawn as deeply and thoroughly as possible. This, in essence, will create a “new” lawn root zone that is a mix of the deposited soil and the underlying lawn and its soil. The goal is to eliminate, as much as possible, the formation of layers in the “new” lawn root zone by thoroughly mixing the original lawn’s soil, the layer of the original, dead lawn, and the flood-deposited soil.

After leveling and firming the “new” lawn soil, it can be sodded or seeded as any new lawn would be established. Cool-season grasses can be seeded anytime between Aug. 20 and Sept. 30 (buffalograss should be seeded in April/May). Sod can also be used to provide an instant lawn. Do not sod over existing dead or buried vegetation. The old dead layer of lawn grass must be thoroughly tilled into the soil before laying new sod.

Written 18 September 2013

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Today’s post can be heard on the public radio show Crop to Cuisine, hosted by Dov Hirsch.

Crop To Cuisine

On the outskirts of Minneapolis, in a town called Eden Prairie, a vegetable patch is growing. This is not an average kitchen garden; the corn, beans, melons and tomatoes have a mission greater than feeding their gardener. Instead of filling plates with salad and side dishes, the plants here serve as canaries in a coal mine, providing early warning for problems cropping up on nearby grass.

Known as indicator plants, the vegetables are part of a holistic approach to turfgrass management on the professional practice fields of the Minnesota Vikings football team.

“The public thinks we practice at the Metrodome (inMinneapolis); they don’t know we have fields,” says Grant Davisson, Head Sports Turf Manager for the Vikings, who play in an indoor stadium. “But we have a lot of activity all year on this turf, from the end of March through the end of the season.”

With higher humidity and rainfall – they receive 30 inches per year – disease poses a challenge for managing the 210,000 square feet of turfgrass the Vikings practice on. Leaf spot, pythium, pink snow mold and Brown Patch are chronic problems.

Many high-use sports fields rely on a combination of play rotation and pesticides, but this facility is next to a riparian area protected by law. Because all of the runoff dumps into the wetland, Davisson is conservative in his turf treatments and prefers alternative means to controlling problems. “We don’t want any runoff, and we want as few applications as possible.”

That’s where the vegetables come in. In a 10-foot wide swath, watermelons, corn, tomatoes and soybeans act as sentinels for conditions that spur disease, succumbing to sickness a few days before the problems show up on the turf.

Rooted in the knowledge that disease outbreaks require the right environmental conditions to thrive, Davisson watches his vegetables for signs of oncoming turf problems. “Watermelons get hit by pythium, and though it’s not the same pythium that affects turf, they both need the exact same conditions,” he said, speaking of the disease that sends chills through turf managers’ spines due to its rapid destruction.

“It’ll hit the watermelons on the third hot, humid day and they’ll get killed, often by July 1. But once it shows up on the watermelons, I have a day or two lead time to spray the turf.” That’s all the time he needs to target his controls, knocking the dread fungus back behind scrimmage lines to keep it in check.

“Then we get cloudy days and the tomatoes get leaf spot. I’ve tracked it – three to four days later the turf gets leaf spot.” Affecting crown, rhizomes and roots in addition to leaves, in the heat of summer it kills the turf, leaving bare spots. “I hate leaf spot. It’s a bigger problem on rye than bluegrass.”

Replicating his plots in full sun and part shade, Davisson mimics the variable conditions on his fields, which receive differing amounts of sunlight. Applications of fertilizer are made at the same time to keep turf and vegetables even.

In addition to watermelon and tomatoes to watch for pythium and leaf spot, Davisson has corn and soybeans for rust. The peppers and peas are “because I like to eat them.” Harvested produce goes to coaches and staff.

Following a set schedule for fungicides calls for applications to be made every 90 days, and on fields this size, every application cost $35,000 to $40,000. But through this vegetable sentinel system, Davisson has been able to stretch out applications to 142 days between applications, saving money and lowering the impact on the environment. “It’s easily to most successful means to gauge disease,” he said, “and I save two applications per year. That’s a lot of money.”

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With apologies to Frank Loesser, his song, Baby It’s Cold Outside, has been running through my head with a few changes:

We really can’t sleigh (baby it’s dry outside)

The warmth’s got to go away  (baby it’s dry outside)

This winter we’ve been (hoping that snow’d drop in)

Not very nice (I’ll warm up the hose, it’s stopped up with ice)

Trees aren’t the only thing that need water in a dry winter – and boy, is it dry.  The federal Climate Prediction Center has said most of the Front Range and all of eastern Colorado is in a moderate drought.  We’ve gotten just a whisper of water since July, so monthly watering of your landscape is a must. 

In a previous post, how to water your trees was described, but lawns, too, need a drink.  “Established lawns will benefit from watering, but the critical ones that need moisture are the ones that are new,” says Dr. Tony Koski, Extension Turf Specialist with Colorado State University Extension.  If you put down sod after September 15, you should water it. 

Even if you don’t have a new lawn, watering the grass is important, and if you’ve been plagued by lawn mite problems in the past, water that yard soon, he said.  “This is when mite populations start to rise, especially on warm days when they get a little active and frisky.  They’re frisking around, the population starts to rise, and though mites haven’t started to damage the lawn, their potential to do so increases with their numbers.”  Mites prefer bone-dry grass, so hold them at bay with moisture. 

To water a lawn in winter, warm days with temperatures above 45-degrees is a must.  Fortunately we have plenty to choose from, since we’re in the 50’s and 60’s several days per week.

Drag out your hose with a sprinkler, or set the water to a slow trickle.  “The problem is that everything is frozen, but you don’t want water puddling on the lawn.  And the worst thing is forming a layer of ice on it; that really harms the turf.  So it probably won’t take more than a quarter to half-inch of water before you get standing water and puddles.”

Set your timers to tell you when to move the hose or shut off the water.  Most importantly, disconnect the hose from the house before evening so you don’t run the risk of frozen pipes.

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Heading into winter is when many people forget about yard care, putting the lawnmower away for the season. We fill our time cleaning the house, scrubbing the nooks and crannies we ignored in favor of being outside. But after a summer of heat, a fall of drought and a winter that’s slow in arriving, your lawn needs a little coddling to keep it healthy until spring.

The ability of turf to survive winter depends on healthy root systems. The stresses of summer often take their toll on roots, which need to regenerate in fall during cooler weather. To help lawns recover, fertilize now.

Late season application of nitrogen is recommended for Kentucky Bluegrass, Tall Fescue or Perennial Rye. Fertilize by applying 1 pound of nitrogen per thousand square feet during the first week of November, while the grass is still green and the ground isn’t frozen (if you have sandy soils, don’t fertilize after September). With the warmth lingering late this year, lawns will get the benefit of a slow cool down of the soil, which will give fertilizer the chance to help roots regrow.

Nitrogen is the most important food to feed the turf – extra potassium or phosphorus is not as critical. At this time, nitrogen in the fertilizer should be from sources such as urea, ammonium sulfate or others that don’t need microbes in the soil to release them. Soil microbes slow their activity during cold weather, which may delay release of
nitrogen to the plants, making the late application unsuccessful.

For quick benefit to plants, make sure the soil is moist, which helps the nitrogen dissolve easily. If the ground is dry, irrigate a day before fertilizing. But if you’ve already blown out your system for the winter, apply fertilizer just after one of our rain squalls have passed through.

Then protect roots from drying out during winter by giving it a bit of water if we’re having a dry spell. Dry soils can lead to dieback of the root system, which will limit the top growth of turf during the growing season.

Typically, lawns benefit from watering once every four weeks if we are not getting much rain or snow fall. Keep tabs on how much rain or snow falls at your house – not across town or in Denver where the TV stations are located – and water your lawns when we don’t get 1 inch of water, cumulative, over four weeks.

The late fertilization means lawns will green up early in the spring but not put on a lot of top growth, saving you the effort of mowing before you’re ready to swing into summer chores. Keep in mind that the March-April application may not be needed if you fertilized in November the previous year. As long as the turf greens up and grows, delay fertilizing until May or June.

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Cast your mind back in the not-so-distant past, to early October last year.  The days were warm, the nights crisp, and frost nipped at gardens but the season was not yet at an end.  Lulled by temperatures swinging from 21F to 88F, gardeners delayed the chores of putting the landscape to bed for winter. 

Frozen backflow preventer - photo courtesy of ALCC.

Suddenly, the weather threw us a curve ball, plummeting temperatures to a chill 16 degrees on October 10.  Plants froze, and so did sprinkler systems.  Some were lucky, escaping harm to their pipes.  Others didn’t see the damage until spring, when they started up their systems to water yards.

 That’s when gushers erupted from backflow prevention valves (the brass valve on the outside of homes), cracked by water turning to ice in the sudden freeze.  Calls to sprinkler companies skyrocketed, and homeowners shelled out $300 to $400 for repairs.  Vows were made to never let this happen again.

But Mother Nature is having hot flashes, and our landscapes still need water.  The resulting seesaw between day and nighttime temperatures are a roulette game for irrigation damage.  But you can keep your system safe with a few tips from the Associated Landscape Contractors of Colorado .

– Wrap your backflow preventer for as long as you want to keep your system operational.  Water in the preventer can freeze during cold snaps, so if you haven’t winterized your system when temperatures are due to dip, swaddle the backflow device with building insulation or towels, three to four inches thick, wrapping pipes all the way to the ground.  Cover it all with plastic, then secure it with duct tape.

– Once you decide to put the landscape to bed, winterize the system by shutting off the water and draining the lines.  Most systems in Colorado are designs that require blowout, but a few have manual or auto drains to remove water.  Should you have one of these, consider blowing out the system anyway, since lines settle over time and low spots often develop that hold water.

– Have your system blown out with an air compressor. Even if you’re a do-it-yourselfer for most tasks, blowing out a sprinkler system should be left to the pros.  A quick internet search for instructions on how to do this resulted in so many warnings shouted in bold, uppercase letters that it should be taken seriously.  According to the Hunter Industries website, using an air compressor to blow out lines can result in flying debris, although they don’t say if it’s from sprinkler heads shooting up like rockets out of the lawn.  The caution not to stand over the heads while they’re under pressure is an important safety tip.

To ensure your system is undamaged during blow out, look for a company with professionals certified by ALCC.  These Landscape Industry Certified Technicians must complete over 2000 hours of practical experience and 10 hours of testing in order to meet the standards of best practices the certification requires.   

Make your appointment soon, since October is a busy month for companies that offer winterization service.  Expect the blow out to cost $50 to $100, but it can save you higher costs come spring.

This post was previously published in the Longmont Ledger.

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If your lawn stays thirsty even though you water often, you might have a problem with thatch.  Thatch is a brown, spongy material made of grass stems, living-, and dead grass roots that forms a mat along the surface of the soil.  It resembles peat moss in look and feel. 

Though thatch can be useful in small amounts to help keep the soil cool and the lawn comfortable to walk on, once it gets thicker than a half-inch, it turns into a big problem for lawns.  Plant roots are lazy when it comes to penetrating a resistant soil, and most plant roots will remain in the easy-to-grow area created by thatch, instead of forcing their way into compacted soil. 

Over time, the major part of the grass’ root system gets limited to the thatch layer, which doesn’t hold water or nutrients well.  The result is turf roots drying out and top growth burning back despite excessive irrigation.  Once this happens, the recommended amount of water will not be enough to keep your lawn healthy. 

 Thatch can be a problem on Kentucky bluegrass, bentgrass and fine fescue lawns, but rarely on tall fescue or buffalograss.  To help slow thatch buildup core aerate each year to break it up and encourage roots to grow into the soil profile.  But wait to aerate until fall or put it on your calendar for spring – mid-summer is not a good time to open up a bunch of holes in the soil for the heat to dry out.

Contrary to myth, grass clippings don’t add to thatch problems; use a mulching mower to leave the clippings on the lawn to recycle the nutrients they contain.

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Hosting the family picnic seemed like a good idea months ago, but looking over the struggling lawn, are you wondering what possessed you to say “yes” to this event?  With cousins bringing footballs and aunties croquet mallets, what should be a cause for celebration is now a source of panic. 

If the date is looming while the yard is dying, get it in shape with coaching from an all-pro turf master.  With no room for error before your relatives arrive, here are a few tips from one who knows how to handle the punishment a wild bunch delivers to a lawn. 

“Give it four to six weeks and you can have a pretty good lawn,” says Ross Kurcab, Turf Manager for the Denver Broncos, who keeps Invesco Field at Mile High ready for play.  “It won’t take a lot of traffic but it will get you through the event, after which you can plant for recovery of it.”

Kurcab shared tricks turf managers use to jump start fields for the big show.  His quick fix suggestions aren’t for everyday lawn renovation; instead they’re designed to make you the hero without big league spending.

Identify areas needing to bulk up, making sure spots of bare soil, dead grass or weeds are prepped before over seeding.  “Don’t plant into a patch of weeds.  Dig them out, rototill them up, or use a weed killer before you seed.”  If using a weed killer, check the label to make sure you can seed grass after it’s applied.

 Remove thick mats of grass or weeds before you plant, then run a core aerator several times across the area, poking a lot of holes into the soil.  Rake up the area to rough it before planting.

Under a time crunch, choose your grass wisely; not all germinate and establish quickly.  Perennial rye is the go-to grass of choice for the pros, since it can be coaxed to germinate in a week if temperatures are ideal.

For fast results, pre-germinate the seed by soaking it in water for 24 hours.  “We put a mesh bag of it into a big trash can of water, soaking it to pop the seed coat. It’ll give you a two day head start on getting the seed out of the ground,” he said.  Once soaked the seed is perishable, so drain the seed after 24 hours, fluff it up and sow it within two days.   

How you plant is the difference between rookie and pro, says Kurcab, so err on the side of aggression.  “People think you just throw it on the ground and it grows, but grass seed needs planting.  Get the seed into the soil by spreading it thickly – about five or six per square inch – then sprinkle a half-inch of soil over the top.  Seed is cheap, don’t go too light with it; though this is three times the recommended rate for new lawns, we’re doing a quick fix to get you through the picnic.” 

Rake the area to get the seed into the core aeration holes and break up the cores.  Then lightly roll the area to press the seed against the soil (rental firms may have rollers available). 

Once your seeds are in, water them thoroughly for the first two days, keeping the area slightly squishy.  Then water the area three times daily for 5 minutes for two weeks to keep the top half-inch moist.  After the seedlings are up, slowly wean the water away until you’re watering it along with the rest of the lawn.

Fertilize it when the seedlings get a half-inch tall with regular strength fertilizer.  You’ll need to mow more often to keep fast-growing seedlings even with the mature grass, but no pain, no gain.  And it’s a small price to pay for a winning picnic.

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