Florida Friendly Lawn Management Laurie Trenholm, Ph.D. Urban - - PowerPoint PPT Presentation

Florida‐Friendly Lawn Management

Laurie Trenholm, Ph.D. Urban Turfgrass BMP Specialist UF‐IFAS

2018 MG Turfgrass Field Day

• Tues, Oct 16 9am‐3pm
• Plant Science Research and Education Unit
• 2556 Hwy 318, Citra FL
• Morning research plot tours, afternoon

indoor education sessions

• Meet the IFAS turfgrass researchers and pick

their brains!

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Our Florida Lawn Grasses

Bahiagrass

(Paspalum notatum)

• Advantages

– Good drought tolerance – Low fertility requirements – Low maintenance – Tolerant of sandy, infertile soils – Establishes from seed

Bahiagrass

• Disadvantages

– Produces abundance of seedheads – Open growth habit encourages weed competition – Susceptible to mole crickets – Coarse stems are difficult to mow – Not wear tolerant

Centipedegrass

6

Centipedegrass

• “Poor man’s grass” – very low input
• Watch fertilizer‐ very low rates needed and

too much leads to centipede decline

• Few insect and disease problems
• Light green color
• Slow growing and prostrate
• New cultivar ‘Hammock’ developed primarily

for use in south FL

• St. Augustinegrass

(Stenotaphrum secundatum)

• St. Augustinegrass
• Best shade tolerance of warm‐season grasses, but

varies by cultivar

• Good salt tolerance
• Tolerates wide range of soil pH
• Establishes quickly from sod
• Deep green color
• Requires irrigation much of the year to stay green

and healthy

• Chinch bugs becoming resistant to pesticides

Sugarcane Mosaic Virus

• Outbreaks multiplt

counties around the state

• Floratam most affected

cultivar and will usually result in death

• More resistant Palmetto

and BitterBlue, which may get the virus but do not suffer the damage as Floratam

• No chemical treatments

available

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• St. Augustinegrass Cultivars
• Floratam
• Bitter Blue
• Palmetto
• Delmar
• Seville
• Captiva

Empire Zoysiagrass

Zoysiagrass

• Low‐growing, dense
• Very responsive to nitrogen – lower

rates needed than for St. Aug

• Shade tolerance similar to Floratam
• Hunting billbug pests
• Susceptible to large patch disease
• Tends to get thatchy
• Needs about same amount of water

as St. Aug

• Mowing height 2‐2.5”
• Empire most commonly used, but
• ther cultivars in small amounts of

production

Empire Zoysiagrass

• Goes into dormancy throughout

winter in central and northern Florida

• Greens up slowly in spring (large

patch issues can compound this)

• People will want to apply extra N

fertilizer to green it up – this is not good!

• Homeowners managing this grass

themselves will have to become more familiar with disease management

Nutrients Required for Turfgrass Growth

From Environment:

Carbon Hydrogen Oxygen

Nutrients Needed From Soil or Fertilizer

Micronutrients:

Iron Manganese Boron Copper Molybdenum Zinc Nickel

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Macronutrients:

Primary: Nitrogen Phosphorus Potassium Secondary: Calcium Magnesium Sulfur

Why Fertilize?

• Lawns need nutrients to grow in a healthy

condition

• Grasses grow and turn green in response to

fertilizer

• A properly fertilized lawn is your best

defense against weeds

• A properly fertilized lawn is your best

protection against storm water runoff

• This does not mean overfertilization!

When to Fertilize?

• 1‐4 times a year:

– Spring when growth begins and after danger of frost – Summer – apply iron or low amounts of nitrogen fertilizer – fertilizer important during times of growth, but may not be needed depending on soil characteristics and grass species – Fall – potassium beneficial, imparts cold tolerance to grass – Winter‐ depends on location in state – DO NOT fertilize dormant grass with nitrogen (no fertilizer mid Oct‐April in North Fl and Nov‐ end of March in central Fl)

• South Florida may fertilize year‐round

Warm Season Grass Growth

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What About Other Nutrients?

• Soil test can tell you what is needed
• Turf need for calcium & magnesium low
• In high pH soils, iron & manganese may be

limiting‐ for best results, these should be applied in a chelate form (not oxide form)

Annual Fertilization Rates for Lawngrasses

(Lbs. of N per 1,000 sq. ft.)

Central North Bahiagrass: 1‐3 1‐3 Centipedegrass: 0.4‐3 0.4‐2

• St. Augustinegrass:

2‐5 2‐4 Zoysiagrass: 2‐4* 2‐3

Most zoysia cultivars should get no more than 2 lbs yearly

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How Much to Apply Each Time

• Frequency of application: 1‐4 times yearly
• Each application: maximum amount to apply is 1 lb

N per 1,000 sq. ft. if fertilizer has slow‐release N

• Only fertilize during the growing season

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Fertilizer Calculations

• Divide your yard up (front, back, sides)
• Determine square footage of each area

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40’ 25’

Fertilizer Calculations

• Look at fertilizer analysis on bag (ex. 15‐0‐15)
• Take the amount of N (15% in this case) and

divide it into 100.

• This gives you 6.6 – this is the pounds of

fertilizer that you need for 1,000 sq. ft. to apply 1 lb. N

• This works for ANY fertilizer analysis

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Fertilizer Calculations

• To apply the correct amount:

– Take half of the total amount of fertilizer:

• 15% = 6.6 lbs fertilizer per 1,000 square feet
• Half of this = 3.3 lbs fertilizer in spreader

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Fertilizer Calculations

• To apply the correct amount:

Take the remaining 3.3 lbs, put in spreader and go back and forth at 90o angles

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Two Ways That Fertilizers Can Pollute

• 1. Leaching

through soil profile – this is what nitrogen will do in sandy soils

Two Ways That Fertilizers Can Pollute

• 2. Surface water run‐off

Turfgrass Fertilizer BMPs

• Keep fertilizer off impervious surfaces
• Maintain a buffer zone around water bodies
• Apply only the correct amount – more is not better!
• Soil test – know your pH and soil available nutrients
• Low (or no) phosphorus!
• Only fertilize during the growing season
• Irrigate fertilizer in with about ¼” of water
• Do not fertilize newly planted grass for 30‐60 days

Sweep Up Fertilizer Spills

200 linear feet X 5 feet wide mower = 1,000 ft2 2,000 grams clippings (dry weight) 3.5% nitrogen in the clippings = 70 grams nitrogen = 0.15 lbs nitrogen

Nitrate Leaching from New vs. Established Grass in 2005

100 200 300 400 2

• M

a y 1 6

• M

a y 2 3

• M

a y 1

• J

u n

• 5

7

• J

u n

• 5

1 4

• J

u n

• 5

2 j u n e 5 2 8

• J

u n

• 5

5

• J

u l

• 5

0.5 1 2

5 10 15 20 25

0.3 lb 0.66 lb 1.3 lb 2.0 lb

Newly Planted Sod Established Sod

Nitrogen Rate Study ‐ Nitrate‐N Leaching from Floratam

1 2 3 4 5 Yr 1 FC1 Yr1 FC2 Yr2 FC1 Yr2 FC2 Yr2 FC3 Yr2 FC4 Yr3 FC1 Yr3 FC2 Yr3 FC3 Yr4 FC4 1 lb N 4 lb N 7 lb N 10 lb N

Nitrogen applied as 100% soluble urea

NO3- N Leached (kg ha-1)

Trenholm et al. 2009

Irrigation BMPs

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Overwatering

• Increased disease issues
• Root rot and stunting
• Weak turf stand
• Increased weeds

35

How Frequently to Water

Varies due to:

– Season – Soil type – Shade – Rooting depth – Insect or other pests – Other stresses

Seasonal Frequency of Irrigation

• Zazueta, Miller, and Zhang*:

Winter 4.5‐11.6 Spring 2.7‐6.9 Summer 2.7‐2.9 Fall 4.8‐11.6 *For St. Augustinegrass with a 6” root system under low irrigation regime in the Tampa Bay area

Irrigation Frequency

• Watch grass for signs of stress
• Follow watering restrictions!
• You may water “hot spots” with hose if

needed and if not prohibited by local restrictions

How Much to Water

• Apply 1/2” to 3/4” when turf shows

symptoms of wilt

• This should not vary‐ only frequency

varies!

Short, frequent irrigations Longer, less frequent irrigations

Irrigation System Efficiency

• Calibrate systems to ensure

uniform coverage

• Check for broken heads, etc
• Check for landscape plants

that may block sprinkler from reaching grass

Time Line for Irrigation for New Sod Plantings

Time Frequency Duration

First 7-10 days 2-3 times daily

Short (5-10 mins)– try to keep plant material from drying out

7-10 days after planting Once a day

Apply ~ ¼” water – more will be wasted due to short roots

Next 7-10 days Every other day

Apply ~1/4 to ½” of water

3-4 weeks after planting 1-2 times weekly

Apply ~ ½” water

Which Grass Has Better Drought Tolerance?

• All of our grasses need water to stay

green (about the same amount!)

• Survival often depends more on soil
• rganic matter, shade, rooting depth

than species

Severe Watering Restrictions

• Do soil amendments help?
• Research on these is often not clearly stated
• Often, no significant benefits seen
• When possible, incorporate organic matter

prior to planting sod/seed

• Not practical to try to topdress after turf

establishment to add organic matter

Mowing

45

Mowing BMPs

• Mow at the correct height for the species

– Mowing too low stresses the grass and forces it to use up all saved reserves for shoot growth – Mowing high increased root depth

Mowing Heights

• St. Augustinegrass Standard Height Cultivars:

– Floratam, Bitter Blue, Classic, etc. – 3.5 – 4”

• St. Augustinegrass Dwarf Cultivars:

– Captiva, Delmar Seville – 2‐2.5”

• Bahiagrass: 3‐4”
• Centipedegrass:
• Zoysiagrass: ~2”

Mowing

• Only remove 1/3 of the leaf blade at any one

time

– Grass at 6” should have no more than 2” removed

• Keep mower blades sharpened
• Do not mow wet grass
• Commercial mowers should be washed off

between properties (do you ever see this?)

Scalping is a Major Stress

Two Types of Stresses

• Biotic

– Insect – Disease – Nematode – Weed

• Abiotic

– Drought or over‐watering – Excess or insufficient fertilization – Mowing (scalping, dull blades) – Soil compaction/pH or other soil issue – Temperature extremes – Shade – Traffic – Dog Spots – Standing water/submersion – Saline (recycled/ocean) or poor quality water

Managing Turf in the Shade

• Remove shade sources (trimming trees)
• Reduce traffic in shaded areas
• Increase mowing height if possible – more shoot

tissue for photosynthesis will help turf perform better

• Reduce irrigation in shaded areas
• Reduce fertilization – trying to promote shoot

growth with high fertility will further stress the grass

Shade Tolerant Turf

• St. Augustinegrass = zoysiagrass

Centipedegrass Bahiagrass Bermudagrass = Seashore paspalum

• St. Augustinegrass Shade Tolerance
• Seville, Delmar, Captiva

–Bitterblue

• Palmetto

–Floratam

The “New” Urban Soils

• Retention pond soils typically very high pH‐ 8
• r higher
• Become very compacted‐ impedes root

growth

55

Dealing With High pH

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Dealing With High pH

• Micronutrients iron, manganese not available
• Phosphorous may also be limiting
• Micronutrient deficiencies cause interveinal

chlorosis

57

Dealing With High pH

• Difficult to lower pH effectively
• Elemental sulfur‐ forms sulfuric acid in

presence of sulfur‐oxidizing bacteria

• Short term duration
• Organic matter – humus, peat, peat moss
• Ammonium sulfate as N source

58

Dealing With High pH

• Application of ammonium sulfate, biosolids

as N source

• Topdress with compost, organic matter
• Application of soluble or chelated iron and

manganese

• Foliar fertilization (N and micros)
• Watch for P deficiency

59

Compacted Soils

• Lack of oxygen for

roots

• Roots can’t grow
• Water, other inputs

can’t penetrate

• Can form solid

“hardpan” layer

• Dries out
• Low microbial activity

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Dealing With Compacted Soils

• Aerate/topdress
• Consider foliar fertilization since roots will be

compromised and may be difficult to work granules into soil

• Reduce irrigation run times to avoid runoff ‐

irrigate in segments that let soil dry out to avoid runoff

61

Why Do We Aerate?

• Compacted soils
• Improves roots (increases air)
• Do Florida soils get compacted?

Warm‐Season Grass Growth Curve

Temperature Extremes

• Warm season grasses inherently designed to

grow in hot, high light conditions

• They have temporary cessations of growth

when temperatures drop and/or daylength shortens

• Time agronomic programs to complement

this basic biology, not attempt to offset it

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What Is This Stress?

65

The “New” Urban Soils

• Retention pond soils typically very high pH‐ 8
• r higher
• Become very compacted‐ impedes root

growth

66

Dealing With High pH

67

Dealing With High pH

• Micronutrients iron, manganese not available
• Phosphorous may also be limiting
• Micronutrient deficiencies cause interveinal

chlorosis

68

Dealing With High pH

• Difficult to lower pH effectively
• Elemental sulfur‐ forms sulfuric acid in

presence of sulfur‐oxidizing bacteria

• Short term duration
• Organic matter – humus, peat, peat moss
• Ammonium sulfate as N source

69

Dealing With High pH

• Application of ammonium sulfate, biosolids

as N source

• Topdress with compost, organic matter
• Application of soluble or chelated iron and

manganese

• Foliar fertilization (N and micros)
• Watch for P deficiency

70

Compacted Soils

• Lack of oxygen for

roots

• Roots can’t grow
• Water, other inputs

can’t penetrate

• Can form solid

“hardpan” layer

• Dries out
• Low microbial activity

71

Dealing With Compacted Soils

• Aerate/topdress
• Consider foliar fertilization since roots will be

compromised and may be difficult to work granules into soil

• Reduce irrigation run times to avoid runoff ‐

irrigate in segments that let soil dry out to avoid runoff

72

Why Do We Aerate?

• Compacted soils
• Improves roots (increases air)
• Do Florida soils get compacted?

What Is This Stress?

74

The Burning Question About Dogs and Grass

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The Burning Question About Dogs and Grass

• High salts and N produce burned grass in

areas where urine is concentrated

• How to repair?

– Water in with hose if possible – Encourage dogs to have specific area to use – Replace damaged areas with stolons or plugs – No soil amendments that are effective – Not related to dog’s diet

What Are the Brown Spots in My Lawn?

• Is there evidence of a pattern from a

spreader, mower, sprayer, irrigation head?

– Look for mechanical injury or applicator error

• Look at site conditions (shade, compacted

soils, wet soils)

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What Are the Brown Spots in My Lawn?

• Is the injury random in shape and size or does it

recur in multiple locations?

– Check for insects

• Look at roots – are they black, rotting (fungal

disease)or truncated (soil born insect or nematodes)

• Does shoot system have evidence of chewing on

leaves (insects) or rotting (fungal disease)

• Is shoot system dried out and chlorotic or necrotic?

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Thank you for your attention! letr@ufl.edu