College of

Agriculture and Natural Resources

LAWN VS LORE

Myths: True or False?

Eric Wenger MG 1996Patricia Eng, MG 2014

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Our Vision:

A healthier world through

environmental

stewardship.

Our Mission:

To support the University

of Maryland Extension

mission by educating

residents about safe,

effective & sustainable

horticultural practices

that build healthy

gardens, landscapes, &

communities.

IPM - INTEGRATED PEST MANAGEMENT

“Intelligent person’s method”*

“the selection, integration, and implementation of multiple

pest control techniques based on predictable economic,

ecological, and sociological consequences, making

maximum use of naturally occurring pest controls, such as

weather, disease agents, and parasitoids, using various

biological, physical, chemical, and habitat modification

methods of control, and using artificial controls only as

required to keep particular pest from surpassing intolerable

population levels predetermined from an accurate

assessment of the pest damage potential and the ecological,

sociological, and economic cost of other control measures.”

fgc.edu

*Bob Alde,Eric Wenger

10 COMMON LAWN MYTHS

10) “I must remove leaves from my lawn in fall”

9) “Spring is the best time for dandelion and weed control; that is why stores sell weed and feed products in the spring”

8) “There is no point in getting rid of weeds in my lawn if my neighbors don’t do anything to their lawns”

7) “Wearing spiked shoes is a good way to aerate my lawn”

6) “Grass seed labeled for shade will grow and survive in all kinds of shade”

COMMON LAWN MYTHS

5) “If my lawn has moles, there must be grubs”

4) “Grass clippings create thatch, so I need to bag theclippings when I mow the grass”

3) “I won’t have to mow as often if I mow my lawn shorter”

2) “Lawns are not biologically diverse”

1) “Lawns are the major source of nutrient pollution in the Chesapeake Bay”

MYTH #10: I MUST REMOVE LEAVES FROM MY LAWN IN THE FALL

MYTH #10: TRUE!TOO MANY LEAVES CAN SMOTHER YOUR LAWN

LEAVES MAKE GREAT MULCH AND COMPOST…

BUT GRINDING THEM INTO YOUR LAWN WILL CAUSE DEAD SPOTS. LEAVES CONTAIN LIGNIN WHICH TAKE LONGER TO DECOMPOSE THAN GRASS CLIPPINGS

MYTH #9: SPRING IS THE BEST TIME FOR DANDELION AND WEED CONTROL, THAT IS WHY STORES SELL WEED AND FEED PRODUCTS IN THE SPRING

MYTH #9: FALSEACTUALLY, FALL IS THE BEST TIME TO CONTROL

MOST BROADLEAF PERENNIAL TYPE WEEDS

SPRING IS THE BEST TIME TO CONTROL CRABGRASS AND STILTGRASS

WHICH ARE ANNUAL GRASSY WEEDS

MYTH #8: NO POINT IN GETTING RID OF WEEDS IN MY LAWN IF MY NEIGHBORS DON’T DO ANYTHING TO THEIR LAWN

MYTH #8: FALSEA WELL MAINTAINED LAWN WILL ACTUALLY

STOP MOST WEEDS FROM ESTABLISHING

HEIGHT MATTERS

Mow shorter, get more weeds; mow higher have less weeds.

IT IS THAT SIMPLE!

MYTH #7: WEARING SPIKED SHOES IS A GOOD WAY TO AERATE MY LAWN

MYTH #7: FALSEAERATION SHOES ARE NOT AN EFFECTIVE WAY

TO AERATE YOUR LAWN

Turf Cultivation: Aerating

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MYTH #6: GRASS SEED LABELLED FOR SHADE WILL GROW AND SURVIVE IN ALL KINDS OF SHADE

MYTH #6: FALSELAWN GRASS PREFERS AT LEAST 6 HOURS OF FULL SUN

• GRASS SEED MARKETED AS “SHADE SEED” CAN BE MISLEADING

• MOST GRASSES REQUIRE 6 HOURS OF FULL SUN TO SURVIVE YEAR ROUND

• NO GRASSES SURVIVE YEAR-ROUND IN OUR CLIMATE IN DEEP SHADE AS WHAT WE THINK OF AS A LAWN

• REMEMBER – “GUARANTEED TO GROW” IS NOT THE SAME THING AS “GUARANTEED TO SURVIVE”

• SHEEP FESCUE, CHEWINGS FESCUE AND HARD FESCUE CAN SURVIVE IN HEAVY SHADE AS LONG AS THEY ARE LEFT ALONE: NOT WALKED ON, MOWED OR FERTILIZED

MID-AUGUST TO LATE-OCTOBERIS THE BEST TIME TO SEED YOUR LAWN

• Generally from Mid-August to Late October, BUT

• IF YOUR LAWN IS SHADY, THEN THE BEST TIME TO SOW GRASS SEED IS IN THE SPRING

MYTH #5: IF MY LAWN HAS MOLES, THERE MUST BE GRUBS

Msue.anr.msu.edu

Nbcnews.com

MYTH #5: FALSEMOLES EAT ALL KINDS OF CREEPY CRAWLIES

MYTH #4: GRASS CLIPPINGS CREATE THATCH, SO I NEED TO BAG THE CLIPPINGS WHEN I MOW THE GRASS

• Thatch is the intermingled layers of living and dead stems, roots and leaves that lie between the soil and green vegetation– Thatch impedes water movement, harbors insects and diseases,

ties up fertilizer & pesticides

– Some thatch is good (up to1/2”), but above 1/2” thick, problems can arise

MYTH #4: FALSEGRASS CLIPPINGS DO NOT CREATE THATCH

• Grass clippings are 75% - 80% water and decompose quickly. But don’t leave too many!

• Plant parts that contain higher amounts of lignin, such as stems and roots, are primarily responsible for thatch build up

• Other factors: Type of grass, Proper pH, Active Soil Microbes, Aeration

GRASSCYCLING IS IMPORTANT!

• Encourages a healthier lawn by returning nutrients to the soil, in a slow release form

• Saves time by eliminating the need to bag or rake grass clippings

• Helps protect the environment by reducing the amount of lawn clippings in the landfill

MYTH #3: I WON’T HAVE TO MOW AS OFTEN IF I CUT MY LAWN SHORT

MYTH #3: FALSEIN REALITY TALLER LAWNS PROMOTE STRONGER ROOTS AND LESS WEEDS

HEIGHT MATTERS

Mow shorter, get more weeds; mow higher have less weeds.It is that simple!

MOWING TIPS• Mow on a regular basis

• Remove no more than 1/3 of the leaf blade at each cutting if possible and always have a sharp blade.

• Mow at the correct height for the type of grass– For Fescue and Bluegrass:

• Mow 3 to 3 1/2 inches– Reduce weeds by 50-80%

– Keeps grass greener in summer

– Roots are healthier, soil is cooler

– Thatch is reduced

• Mulching mowers hasten the

decomposition process,

but are not necessary

MYTH #2: LAWNS ARE NOT BIOLOGICALLY DIVERSE

MYTH #2: FALSELAWNS DO SUPPORT BIODIVERSITY

LAWNS SUPPORT BIODIVERSITY AND ARE ALSO PART OF A BIODIVERSE

LANDSCAPE

MYTH #1: LAWNS ARE THE MAJOR SOURCE OF NUTRIENT POLLUTION IN THE CHESAPEAKE BAY

MYTH #1: FALSE

HEALTHY TURF = • LESS RUNOFF• COOLER ATMOSPHERE• MORE OXYGEN

Fact: A PROPERLY MAINTAINED LAWN IS BENEFICIAL IN STOPPING RUNOFF INTO STREAMS, TRIBUTARIES AND THE CHESAPEAKE BAY

LAWNS ARE NOT THE BIGGEST PROBLEM

http://chesapeake.usgs.gov/sciencesummary-nutrientmodelresults.html

http://midshoreriverkeeper.org/wp-content/uploads/2013/02/Ecology-of-Lawn-Maintenance1.pdf

The largest source of pollution to the Bay comes from agricultural runoff, which contributes roughly 40 percent of the nitrogen and 50 percent of the phosphorus entering the Chesapeake Bay.

Chesapeake Bay Foundation

WHAT POLLUTES THE BAY?• Atmosphere – 0.7 million pounds

• Septic – 4.0 million pounds

• All Urban/Suburban Runoff

(includes roads and turf) – 5.6 million pounds

• Forest Runoff – 7.1 million pounds

• Wastewater – 14.2 million pounds

• Agriculture – 17.8 million pounds

Chesapeake Stormwater Network 2012

Dr. Tom Turner 4/26/2012

BILLIONS OF GALLONS OF SEWAGE SPILL AND LEAK INTO OUR WATERWAYS EACH YEAR

https://data.montgomerycountymd.gov/Community/DEP-Reported-Sanitary-Sewer-Overflows/pah9-6f8f

MARYLAND FERTILIZER LAWS

• Restricts the amount of nitrogen that can be applied

– 0.9 pounds total nitrogen per 1,000 square feet

– 0.7 pounds of soluble nitrogen per 1,000 square feet, unless using enhanced efficiency fertilizer.

• Prohibits Phosphorus (P) application unless a soil test indicates it is needed or when a lawn is being established, patched or renovated.

• Prohibits application of nitrogen (N) and phosphorus on turf between November 15th and March 1st.

FERTILIZING TIPS

• Only fertilize actively growing grass and never fertilize frozen ground

• Keep fertilizer off paved surfaces. Sweep up material on paved surfaces.

• Avoid filling your spreader on a grassy surface

KEY POINTS of MARYLAND FERTILIZER REGULATIONS ON NITROGEN (N)

• Do not apply N before March 1 or after November 15th

• Do not apply more than 0.7lb. of soluble N per 1000 ft2

• If fertilizer contains 20% or more slow release N, do not apply more than 0.9 lb. of total N per 1000 ft2 in any one application.

KEY POINTS of MARYLAND TURFGRASS LAWS ON PHOSPHORUS (P)

• Phosphorus (P) cannot be applied for maintenance unless a soil test indicates a need.

• Natural organic fertilizers or products containing P can only be used if less than .25 lbs. P2O5/1000 ft2 per application, and not exceeding .50 lbs. P2O5/1000 ft2 annually.

• All products containing P, prohibited where soils test determine that soil has “optimum to excessive” levels of P.

WHAT ABOUT ORGANIC FERTILIZER?

• The same rules apply for all sources of nutrient fertilizers, including compost! In fact, most of the nutrients that pollute our waterways are from organic sources

• Most organic fertilizers contain slow release Nitrogen and Phosphorus. This limits their use, especially after November 15th

• Each application may not exceed 0.25lb of phosphate per 1,000 square feet with an annual maximum of 0.5lb of phosphate per 1,000 square feet

Things Aren’t Always What They Seem

10 COMMON LAWN MYTHS

10) “I must remove leaves from my lawn in fall” TRUE

9) “Spring is the best time for dandelion and weed control, that is why stores sell weed and feed products in the spring” FALSE

8) “No point in getting rid of weeds in my lawn if my neighbors don’t do anything to their lawns” FALSE

7) “Wearing spiked shoes is a good way to aerate my lawn” FALSE

6) “Grass seed labeled for shade will grow and survive in all kinds of shade” FALSE

COMMON LAWN MYTHS

5) “If my lawn has moles, there must be grubs” FALSE

4) “Grass clipping create thatch, so I need to bag the

clippings when I mow the grass” FALSE

3) “I won’t have to mow as often if I mow my lawn

shorter FALSE

2) “Lawns are not biologically diverse” FALSE

1) “Lawns are the major source of nutrient pollution in the Chesapeake Bay” FALSE

GENERAL HORTICULTURE REFERENCES

• Maryland Extension – Home and Garden: www.hgic.umd.edu

• Virginia Tech Plant Pathology and Weed Science: www.ppws.vt.edu

• Colorado State Extension: http://extension.colostate.edu/

• Texas A and M Horticulture: http://aggie-horticulture.tamu.edu/

TOPIC SPECIFIC REFERENCES

• Center for Invasive Species and Ecological Health: www.invasives.org

• Plants for a Future: www.pfaf.org

• MoCo Dept of Environment Report of Sanitary Sewer Overflows: https://data.montgomerycountymd.gov/Community/DEP-Reported-Sanitary-Sewer-Overflows/pah9-6f8f

• USGS Summary of Transport of Nitrogen and Phosphorus in the Chesapeake Bay Watershed: http://chesapeake.usgs.gov/sciencesummary-nutrientmodelresults.html

• Penn State Introduction to Weeds and Controls: http://extension.psu.edu/pests/weeds/control/introduction-to-weeds-and-herbicides

TURF RELATED RESOURCES• Maryland Extension Turfgrass Council Publications:

http://mdturfcouncil.org/publications-resources/pubs/

• Maryland Turfgrass Disease Control Recommendations: http://mdturfcouncil.org/admin/uploadfiles/tt-38-2-10-d-control-11.pdf

• Maryland Fertilizer Law: http://mda.maryland.gov/pages/fertilizer.aspx

• Montgomery County MD Pesticide Regulations: http://www.montgomerycountymd.gov/dep/community/lawn-care.html

• Montgomery County MD Pesticide Ban Regulation: https://www.montgomerycountymd.gov/COUNCIL/Resources/Files/bill/2014/Packets/20141028_4C.pdf

• Report on Ecology of Lawn Maintenance: http://midshoreriverkeeper.org/wp-content/uploads/2013/02/Ecology-of-Lawn-Maintenance1.pdf

• Science Daily Article “…Insight into Backyard Biodiversity”: https://www.sciencedaily.com/releases/2003/08/030811071121.htm

• Florida Gateway College Turf Topics: www.fgc.edu

Information and Pictures Supplied by Agriculture Departments of:

• North Carolina State University

• University of Nebraska Lincoln

• Penn State University

• University of Tennessee

• University of Maryland

• The Ohio State University

• Virginia Tech

• University of California, Davis

• Texas State University

• University of Southern California

• Clemson University

ADDITIONAL CREDITS

Dr. Tom Turner, Univ of New Mexico

Dr. Peter Dernoeden, U Maryland

Dr. Lee Hellman, U Maryland

Dr. David J. Shetlar, Ohio State Univ

Dr. John Davidson, U Maryland

Prof. Stanton Gill, U Maryland and Montgomery College

Dr. Donald Wyse, Univ of Minnesota

Preston Sullivan, NCAT Minnesota DOT

Art Gover, Penn State University

College of

Agriculture and Natural Resources