Weed Control in Turfgrass Without Standard Chemicals

Eric Wenger, Complete Lawn Care, Inc., and

Chuck Schuster, Retired, University of Maryland Extension

Cultural and Organic Weed

Control

What We Want

The Reality

Cultural Weed Control• Soil pH and Fertilizer

• pH 5.8-6.4- help the desired species of turf thrive, stress some of the weeds.

• Nutrients -• Apply when the desired

species of turf can make use of the nutrients

• Do not apply nutrients at times when weeds will benefit from the added nutrient's if possible. (winter weeds)

Cultural Weed Control•Cool Season Grasses

• Fine fescue• Turf Type Tall Fescue• Kentucky bluegrass• Perennial Ryegrass

•Warm Season Grasses• Zoyzia grass• Bermuda grass

Cultural Weed Control

• Mowing heights• Tall Fescue 3-4”summer• Tall Fescue 2 ½ - 3” winter• KY Bluegrass 2 ½- 3” summer• KY Bluegrass 2-2 ½” winter• Fine Fescue 2 ½ -31/2” S• Fine Fescue 3” winter

• Aerate compacted soils• Add organic matter (40-50#)• Correct drainage

• Grass clippings- how best to use them.

Cultural Weed Control

• Mowing heights can be useful in controlling (not eliminating) some weeds but not all weeds

• Crabgrass needs ultra violet light for seeds to germinate. A taller mowed lawn can help with this.

• Japanese stiltgrass will out compete no matter what mowing height used.

• Appropriate mowing height is important overall. Mowing at heights recommended by University of Maryland Extension is the best starting point.

Cultural Weed Control

• Appropriate fertility is useful also. • Plants do not know the difference between organic

nutrient sources or synthetic nutrient sources. • Apply at the proper time and in amounts that the plant

can actually use. • Soil test is required or any product that contains

phosphate (Fertilizer Use Act of 2011) and it makes sense.

The Desire to Control Unwanted Plants

•47% of all pesticide products used in turf are herbicides.

•Selection of the proper product is extremely important, cost, results.

Organic Weed Control -• Pre emergent • Corn Gluten• Suppress annual weeds• Source of nitrogen

• Recommended amount may exceed amount of N allowable in MD per 1000ft2 – the Fertilizer Use Act of 2011

• Orland’s Safe-T-Weed G• Earth Harvest Gluten L• Gluten-8 OLP ™ L• Concern® Weed Prevention Plus® 8-2-• Espoma Organic Weed Preventer• Green It Corn Gluten Weed Preventer• Preen Organic

Really Does Not Work Even at The Higher Rate.

Organic Weed Control

• Soybean Oil, Purely Organic Puredefense Crabgrass Preventer, suppresses crabgrass. Area can be reseeded immediately after application, Do not use on young grass.

• Soybean Oil, Purely Organic Puredefense Weed Shield-Post emergent, selective product for control of some broadleaf's in existing turf.

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Organic Weed Control• Iron Products- Bonide Weed Beater Fe, Fiesta Turf Weed

Killer, Natria Lawn Weed Control, Pulverize Weed Killer, Weed Beater Fe, Whitney Farms Lawn Weed Control.

• Iron Chelate, provides same day results. •Rainfast in 3 hours•Thoroughly wet the weed to point of runoff. •Retreat site in 3 to 4 weeks.•Use between 50 – 85 Degrees F.

Post Emergent Products

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Organic Weed Control• Non Selective

• These weed-control products are botanically based oils (e.g., clove oil, eugenol, and d-limonene), soaps (e.g., pelargonic acid), or acetic acid that control weeds by destroying the leaf cuticle or causing cell leakage that rapidly leads to death.

• Unfortunately, because these herbicides kill only green parts of the plant they contact, they don't provide long-term control of weeds with extensive root systems or underground storage structures such as rhizomes, tubers, or bulbs.

Organic Weed Control - Post emergent

• HALO Eugenol & Clove Oil• Soil Mender Enhanced Vinegar RTU Herbicide -10% vinegar, Orange Oil, molasses & natural surfactant

• Avenger® - Citrus oil• AXXE – herbicidal soap • Fiesta® - Iron • Burnout- either 20 grain vinegar or citric acid and clove oil

• Eugenol & Clove Oil- be aware that some reports of it being an attractant for

Japanese Beetles. Much like a lure, it will bring in large numbers of them after

application. • Timing is important.

Avenger

• Avenger Herbicide• Citrus Oil Product• Destroys plant material by dehydration of the plant.• Rates vary by size of plant. • Not inexpensive.

Organic Weed Control

• Dr. Kirchner Natural Weed Killer• Ocean Salt Based, with fatty acid soaps and citrus acid• NOT FOR USE ON LAWNS• Label states safe to replant within hours- landscape

areas.

Organic Weed Control • Safergro Weed Zap, Weed Slayer• Non selective• Please note that the pH of the water should be between 3-4 to deliver the best

results.• Recommended to treat the water first prior to mixing in the

product. In the case that it’s done after the product is already in the mixing tank then get the product applied ASAP (e.g. within the next 30 minutes).

• Controls smaller broadleaf and grassy weeds up to 6 inches tall• Spray to the point of runoff• Shake well before use, it separates in storage. • Claimed long term residual. • It takes about one week to start working as it’s decomposing the plant from the inside out

– it’s not a burn down.

Organic Weed Control

• Potassium Soaps or Salts of Fatty Acids• Safer Brand Fast Acting Weed Control and Grass Killer • Fast Acting Weed and Grass Killer

Contact, not translocated.Reseed in 2 daysControls plants applied to, even desired species of turf.

Organic Weed Control

•Acetic acid, cinnamon oil, iron chelate, potassium salts of fatty acid, citric acid and clove oil.

Flame

• Turns water in plant to steam which causes the cells in the plant to explode

• Only uses on small plants• Use on patios, brick walkways• Spot treat in Lawns

• Remember• You MAY NOT make your own mixture up, this makes you a producer and

subject of Federal inspection. • Purchase already products manufactured by others!

•Questions?