Master Gardenerweedhandouts


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Master Gardenerweedhandouts

  1. 1. What is a Weed? Weeds in the Horticultural Plant out of place? Setting Plant with undesirable characteristics? Plant with undiscovered virtues? David Fischer Dane County UW-Ext Crops and UW- Soils Agent Or some other definition? What is a Weed Seed Dormancy Flowers/vegetables Seed Dormancy – Breeding has removed dormancy Abundant seed production – Seeds become less valuable if dormancy exists Seed survival Vegetative reproductive structures Weeds Lack of beauty, has offensive odor – Dormancy allows weeds to survive harsh environmental conditions Toxic/ Noxious – May have different levels of dormancy within same plant Seed Survival Seed Production Flowers/Vegetables Flowers/Vegetables – few seeds per plant – Several years under ideal storage conditions – Sweet corn, up to 1000 – Pumpkins, several hundred – “Seedless” watermelon Weeds – Documented survival after 100 yrs of burial Weeds – Survival is possible with some species after composting – Common purslane, 1,000,000+ purslane, – Common lambsquarters, 100,000 lambsquarters,
  2. 2. Vegetative Reproduction Toxic/Noxious Flowers/Vegetables Noxious – Very few perennials – those that are very few – Weed by law spreading root systems (Kentucky bluegrass) – Why? Weeds Toxic – Perennials with spreading vegetative structures – Hazardous to humans and/or domesticated – Annuals when pulled stem re-roots re- animals – Tillage can propagate Grass ID Chart Poaceae Grass Family Desirable species tend to be perennial Weedy species – Many are annuals – Perennials can usually be controlled culturally Identification via ligule and auricle Giant Foxtail Yellow Foxtail Hairy Ligule, Hairy leaf surface Hairy ligule, long hairs at leaf collar
  3. 3. Large Crabgrass Green Foxtail Membranous ligule, hairs on leaf blade Hairy ligule, no hairs leaf blade Smooth Crabgrass Barnyardgrass Membranous ligule, few hairs on leaves NO ligule Quackgrass Sandbur Downy brome HAS auricle Rounded stem, soft hairs Flat stem, hairy ligule Fused sheath
  4. 4. Polygonaceae Prostrate Knotweed Grows prostrate, high salt tolerance Buckwheat family Key family ID characteristic is an Ochrea – Membranous structure found at leaf nodes Several common weeds Wild buckwheat Japanese Bamboo Red Sorrel Curly Dock Chenopodiaceae Goosefoot family Stems tend to have vertical lines Also have beet, Swiss chard and spinach Seed usually irregular shaped
  5. 5. Kochia Common Lambsquarters Common near railroad tracks, Resistant to many herbicides Leaves covered with white mealy substance Prostrate Pigweed Amaranthaceae Very few hairs, thin leaves Pigweed family Monecious plants mainly, some dioecious Most members have red tinge to underside of plant Celosia or cockscomb also in this family Somewhat limited as pests in horticulture Redroot Pigweed Smooth Pigweed Dull leaf color, rough textured plant via small hairs Shiny leaf surface – due to lack of hairs on leaf blades
  6. 6. Tall Waterhemp Carpetweed New plant to WI, dioecious, glabrous Prostrate growing Leaves in whorls Does not have stiff hairs Catchweed Portulacaceae Bedstraw Common purslane Semi-prostrate Semi- Succulent leaves growing Prolific seed Leaves in whorls producer Stiff hairs that Stems will re-root re- catch clothing Ornamental species – Rose moss Caryophyllaceae Common Chickweed Lower leaves Pink Family petiolate Plant glabrous – Opposite leaves Common in – Flowers parts in fives lawns Annual Flowers – Carnation – Baby’s breath
  7. 7. Mouseear Chickweed White Campion or Cockle Perennial Leaves are sessile Leaves opposite Long hairs on plant Soft hairs cover plant Common in lawns White flowers Annual, biennial, perennial? Brassicaceae Yellow Rocket Deeply lobed leaves Shiny appearance due Mustard family to lack of hairs – Extremely common to WI Flower parts occur in fours Seed pods are a silique or silicle and contain a false partition All cole crops also in family Shepherdspurse Wild Mustard Winter annual, forms rosette Christmas tree shaped leaves Triangular seed pod Serrated leaf edge Kidney shaped cotyledons Dull appearance due to leaf hairs
  8. 8. Field Pennycress Fabaceae Usually a winter annual Shiny leaf appearance Leaf edges wavy Almost a unique shade of green for leaf color Black Medic Penny shaped/sized seed Trifoliate leaf pod Annual, biennial, perennial Common in some lawns Family also contains pea, bean, clover, lupine, soybean, peanut Oxalidaceae Euphorbiaceae Yellow woodsorrel Shamrock shaped leaf Spurge family Yellow flower Found in lawns Flowers create special cluster called cyathium (compacted floral structure) Several economically important members Rather unique seed pod – Tapioca or cassava – Castor oil – Natural rubber – poinsetta Prohibited noxious Leafy Spurge Prostrate/Spotted Spurge Plant contains white sap Perennial White plant sap Found in fields, ditches, Prostrate growth, annual, native right-of -way Found in sidewalk cracks
  9. 9. Velvetleaf Malvaceae Common in agronomic setting Large seeded plant Mallow family Also called buttonweed, Economic importance elephant ears, velvetweed Leaves have soft velvet feel – Cotton May have offensive odor – Hollyhock – Hibiscus – Okra Tend to have rounded leaves and seed pods that form a ring of seeds Common Mallow Apiaceae/Umbelliferae Carrot Family Rounded leaves and stem Seed pod will form a ring Many are biennials May be confused with Inflorescence is usually an umbel hollyhock as a seedling Important economic Found in gardens, disturbed areas – Carrot, parsnip – Dill, caraway, parsley – Celery, chervil Important human safety – Wild parsnip, poison hemlock Wild Carrot Wild Parsnip Aka Queen Anne’s Lace Biennial Contains psoralen Common in disturbed areas, right of a photosensitive chemical way, road ditches Biennial Problematic to carrot breeders Found in disturbed areas, right of way, road ditches
  10. 10. Lamiaceae Convolvulaceae Mint Family Morningglory Family Lavender, basil, coleus, Morningglory, sweet potato oregeno, sage, thyme Field Bindweed 4 sided stems Prohibited noxious vine, rare in horticulture Ground Ivy Common in lawns Extremely diff. control Prostrate growing square stem Eastern Black Solanaceae Nightshade Nightshade/Potato Family Economic members – Pepper – Tomato Leaves commonly have – Potato holes – Tobacco Underside of leaf black or purple – Petunia, nicotiana Berries green to black, Many species can be poisonous toxic Common in gardens, disturbed soil Jimsonweed Plantaginaceae Leaves have very strong Bracted offensive odor Strong hallucinogen Seed pods form a bur 1 to 2 Buckhorn inches in diameter Large white flower Plant can exceed 5 ft tall Blackseeded/broadleaf
  11. 11. Canada Thistle Asteraceae Prohibited noxious weed Perennial Very few spines on stem Among the largest of plant families Usually purple flowers Flowers made up of ray and disk florets or Dioecious just disk florets Limited food plants – Endive, lettuce, chicory Extensive ornamental list – Sunflower, aster, dahlia, daisy, zinnia, etc Plumeless Bull Thistle Biennial Thistle Rough hairs cover leaf surface Older plants large stiff spines Far from plumeless Stem is covered in spines Midrib of leaf has hairs on underside Problem of pastures Common Sowthistle ssp. Ragweed Several very similar plants Pollen is source of hay fever All have yellow flowers Common in disturbed soils White latex sap gardens, fields, flower beds Leaves with small spines Monecious plant One species perennial Giant Ragweed Leaf auricles larger on Spiny than Annual
  12. 12. Common Dandelion Chicory Common on road sides, right of ways Biennial Used in teas History as being used as folk medicine Smallflower Horseweed Galinsoga Rare in horticultural setting ROUNDUP RESISTANT Prolific seed producer AKA quickweed Extremely small seed Rapid growth after germination Common in gardens Once established hard to control White ray florets surrounding yellow disk florets Prickly Lettuce Similar to sowthistle Exception is spines on midrib and stem Mayweed Pineappleweed
  13. 13. Pest Management Options Goldenrod Western Salsify Cultural Mechanical Biological Chemical Integrated Pest Management Cultural Control Options Judicious use of all available options to Lawn control pests – Mowing height » Taller is better Management is based on pest species – Fertilization » Optimum levels Considers environmental, ecoloical, and ecoloical, economical aspects – Water » Deep if done Cultural Control Options Mechanical Weed Control Garden Flower beds and vegetable gardens – Rototiller – Proper fertilization » Prior to planting » Inter row spaces – Mulch – Hoe Lawn – Proper planting time and spacing – Dandelion spade or knife – Thatching – Control insects and diseases – Plug aeration
  14. 14. Chemical Control Chemical Use Safety is of utmost importance Use is limited in home horticulture setting Herbicides are the safest of the ‘cides’ ‘cides’ Too many different species in small area – Skin/eye irritation most common concern Most successful if based on differences in Homeowner products safest of the herbicides growth habit – Annual or biennial vs perennial Must READ and FOLLOW label directions – Grass vs broadleaf Label Precautions Preen(dinitroanaline) Make sure species and use are listed Controls germinating seeds i.e. may be labeled for lupines Not labeled for all plants growing in garden or flower bed – But not as cut flower Labeled for crop as a transplant May not cause visible harm to plant – But not for crop as a seed – However, not labeled due to incomplete safety data Flower beds (Preen) Weed and Feed’s (broadleaf) Usually 2,4-D or triclopyr 2,4- May slow growth of transplants Growth regulators Human safety of less concern – Unless used as cut or dried flowers Oldest of herbicide families – Dates back to WWII Cultural methods probably best option – Mulch, fertilization, proper planting Affects auxin production and regulation
  15. 15. 2,4-D Safety 2,4-D Cautions Lower LD50 than many herbicides used by Pet and child safety homeowners Can volatilize Offset by low use rates on a per area basis – Injury other susceptible plants » Grapes As with all chemicals proper safety » Cucurbits important » Ornamental flowers Pets may react to treated areas or several days Glyphosate Glyphosate Roundup, Ranger, Rodeo, etc Non-selective herbicide Non- – Different formulations – Active ingredient is glyphosate No soil residual Among the safest of all active ingredients Additives still cause for human concern When should it be used? Interrupts ESPS synthase Why shouldn’t it always be used? Why Use Glyphosate Why NOT use Glyphosate Human and environmental safety No selectivity Excellent control of a wide range of plants Overuse may result in tolerance or resistance Easiest product for homeowner use for control of brush Some other products work better in specific situations
  16. 16. Weed ID Resources
  17. 17. Dane County Extension Staff Dane County Extension Staff