WEEDS!

Paul BendaArgonne Garden Club

May 2013

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Or rather…

The cons outweigh the uses.

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Why are some plants weeds?• Most noxious weeds are of Eurasian origin.– Introduced for forage, erosion control, wildlife (Crownvetch).

Culinary uses (Garlic mustard).– Accidental contamination of cereal grain supplies (Canada

Thistle, Velvetleaf). – Many not considered “weeds” back home (Purslane).

• Grow early/late compared to natives/crops.• Able to grow well where other plants cannot.• No major pests, diseases.

• No major economic uses, just damage.

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Some Useful Weeds

Creeping Charlie, Gill-over-the-ground – Glechoma hederacea, perennial, mint family.• Beer clarifier & preservative, predates hops. • Herbal tea.• Cooked & fresh leaf.• Leaves high in Vitamin C.• Groundcover.• Brittle stems root easily.

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Some Useful Weeds

• Dandelion – Taraxacum officinale, perennial, lettuce family.

• Single plant can make over 5000 seeds/year.• Leaves usually cooked, high in vitamins, minerals.• Wine from flowers.• Root tea is digestive tonic and diuretic.• Roots resist shallow weeding.

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Some Useful Weeds

• Lambs Quarters – Chenopodium album, annual, beet family.

• Important food plant in ancient Europe & modern India.

• Nutritious leaves raw or cooked, similar to spinach.• Seeds nutritious, similar to Quinoa.

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Some Useful Weeds• Purslane – Portulaca oleracea, annual, purslane

(moss rose) family.• Widely eaten in Europe & Mexico - nutritious

leaves raw or cooked, high in vitamins, Omega-3 fatty acids.

• Very drought tolerant, can switch to CAM.– Traps CO2 at night, – Converts to malic acid then glucose in day. – Morning picked leaves the most sour.

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Weed Propagation: Roots & Stems

• Mainly perennials.• Very hard to control due to extensive

underground reserves.

• Root: Crownvetch, Canada thistle, bindweed.– Roots may go over 10 feet down.

• Stem: creeping charlie, quackgrass.– Weave into turf, among cultivated plants.

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Weed Propagation: Seeds• Mainly annuals/biennials.• Fast growing early in season (cool season).• Produce thousands of seeds, usually wind

dispersed.• Seeds may last to 15-40 years (up to 100 years) in

soil.• Plenty of seedy perennial weeds (Thistles).

“One years seeding makes seven years weeding.”

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The Nastiest Weeds of ArgonneSubject to debate by area & gardener.

• Crownvetch• Canada thistle• Spotted spurge & purslane• Prickly lettuce & dandelion• Bindweed• Creeping Charlie• Quackgrass , orchardgrass & crabgrass.• Add yours here…

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The Nastiest at Argonne: Crownvetch• Coronilla varia, perennial, bean family.• Imported from Europe for erosion control.• Extensively planted by US & state government

on mine spoils, highway embankments.• Roots grow over 10 feet.• Seeds last 15 years in soil.

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The Nastiest at Argonne: Canada Thistle

• Cirsium arvense, perennial, lettuce family.• Vast root system stores nutrients.• Repeated pulling/mowing to deplete reserves.• Prolific seed producer: wind dispersal.

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The Nastiest at Argonne: Spotted or Prostrate Spurge

• Euphorbia maculata, annual, spurge family.• Native to N America.• Stems fragile, milky sap irritating to skin.• Strong fibrous roots, hard to pull.

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The Nastiest at Argonne: Prickly Lettuce

• Latuca serriola, annual/biennial.• Extensive brittle tap root.• High seed production: wind.• Gets very spiny with age.• Bitter milky sap is soporific and analgesic.

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The Nastiest at Argonne: Bindweed

• Convolvulus arvensis, perennial, Morning Glory family.

• Extensive brittle root system.• Major agricultural weed.• Choking vine produces seed.

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The Nastiest at Argonne: Grasses

• Quackgrass: creeping perennial, extensive brittle root system.

• Orchardgrass: bunching perennial, very tough.• Crabgrass: warm annual, brittle stems.

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Weed Control: Methods

• Cultivation, weeding, pulling• Trenching, edging• Mulch, covering• Mowing• Chemicals• Fire

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Weeding Tools

• Cultivation: hoe, cultivators.• Digging: weeders, trowels, spades, pitchforks.• Trenching, edging: flat spades, edgers.

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Hand Pulling is…Labor Intensive

…but very effective.

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Weed Control: Edging and Trenching

• Edging: clean look, best for turfgrasses.• Trenching: best for crownvetch, bindweed,

quackgrass, orchardgrass.

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Weed Control:Mulching

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Don’t give up!