Weeds Identification Topic 2044 Mr. Christensen

Why are weeds weeds? Weeds are plants out of place. Reduce crop Yields, compete for water, nutrients and/or light. Reduce crop quality Some are poisonous Host for disease and insects Degrade aesthetics

Weed Characteristics Produce huge numbers of seeds per plant. Many are self-pollinated, allowing one single plant to produce thousands of seeds. Seeds resist decay. Seeds remain dormant in the soil. Seeds have several dormancy mechanisms.

Weed Characteristics Seeds can mimic crop seed size and shape. Leaves and stems adapt to repel grazing animals. Low growth habit allows weeds to survive in alfalfa fields that are cut three or four times a year. Avoid control mechanisms.

Weed hosts for nematode and insect pests Weed Host for Nightshades Colorado potato beetle Redroot pigweed White mold Common lambs quarters Root aphids Common lambs quarters Soybean cyst nematode Various weeds Aphids that carry barley yellow dwarf virus

Impact on Crop Production Corn yield reduction varies by weed species in 10 feet of crop row 30 giant foxtail—13-14% 27 velvetleaf—21-34% Dry bean yield losses with 30 weeds per 10 feet of crop row Hairy nightshade 45-55% Common ragweed 5-45% Wild proso millet 12-31%

Impact on Crop Production Soybean/weed competition (% reduction) Weeds per 10 ft. Low yield yr High yield yr Cocklebur Smartweed Giant foxtail

Life Cycle One Way to Classify Weeds Summer Annuals Winter Annuals Biennials Perennials-simple and creeping

Summer Annuals From Michigan Field Crop Pest Ecology and Management-Michigan State University Extension Bulletin E-2704

Summer Annuals Examples Barnyardgrass Shattercane Wild Oat Large Crabgrass Smooth Crabgrass Giant Foxtail Yellow Foxtail Green Foxtail Fall Panicum Wild-Proso Millet Witchgrass Woolly Cupgrass Longspine Sandbur Ladysthumb Pennsylvania Smartweed Wild Buckwheat Ivyleaf Morninglory Pigweed (Redroot,Smooth) Eastern Black Nightshade Common Lambsquarters Common Cocklebur Jimsonweed Common Sunflower Common Ragweed Giant Ragweed Velvetleaf Common Purslane Venice Mallow

Lambsquarters Velvetleaf Yellow Foxtail Common Purslane Redroot Pigweed University of California common.html

Winter Annuals Examples Downy Brome Field Pennycress Virginia Pepperweed Shepherd’s Purse Wild mustard Horseweed Common chickweed Prickly Lettace Henbit From Michigan Field Crop Pest Ecology and Management-Michigan State University Extension Bulletin E-2704

Horseweed Common ChickweedShepard’s Purse Wild Mustard University of California common.html Virginia Technological University id/dauca.htm

Biennials Examples Yellow Rocket Bull Thistle Common Mullein White Campion Wild Carrot Virginia Technological University From Michigan Field Crop Pest Ecology and Management- Michigan State University Extension Bulletin E-2704

Common Mullein Wild Carrot Bull Thistle Virginia Technological University

Perennials Examples Curly Dock Dandelion Quackgrass Yellow Nutsedge Johnsongrass Field Bindweed Canada Thistle University of California From Michigan Field Crop Pest Ecology and Management- Michigan State University Extension Bulletin E-2704

Yellow Nutsedge Curly Dock Quackgrass Canada Thistle University of California

Poisonous Plants House Plants—Hyacinth, Narcissus, Daffodil, Oleander, Dieffenbachia, Rosary Pea, Castor Bean Cornell University-

Poisonous plants Flower Garden Plants—Larkspur, Monkshood, Autumn Crocus, Star of Bethlehem, Lily-of-the-valley, Iris, Foxglove, Bleeding Heart Iris Star of Bethlehem Cornell University-

Poisonous Plants Ornamental Plants—Daphne, Wisteria, Golden Chain, Laurels, Rhododendrons, Azaleas, Jasmine, Lantana Camara, Yew Jasmine Cornell University- Wisteria

Poisonous Plants Vegetable Garden Plants-Rhubarb Cornell University- Rhubarb

Poisonous Plants Trees and Shrubs-Wild and cultivated cherries, Oaks, Elderberry, Black Locust Elderberry Cornell University- Cherries

Poisonous Plants Black Locust Cornell University- Horse chestnut

Poison Ivy Poison Oak Poison Sumac

Poisonous Plants Plants in wooded areas-Jack-in-the-Pulpit, Moonseed, Mayapple, Mistletoe University of California Mayapple Misletoe Cornell University-

Poisonous Plants Jack in the Pulpit Cornell University-

Poisonous Plants Plants in Swamp or moist areas-Water Hemlock Cornell University-

Poisonous Plants Plants in Fields-Buttercups, Nightshade, Poison Hemlock, Jimson Weed Belladonna/Nightshade Jimson Weed Cornell University-

Poisonous Plants Cornell University- Pokeweed Milkweed

Medicinal Plants Belladonna Dandelion Dill Garlic Hamamelis witch hazel Aloe Vera Arrowroot Basil Jasmine Olive Radish Rose Wormwood Celery Cornell University- University of California

Weed Identification Laboratory Learn to identify 20 common weeds. Utilize seeds, plant parts, and live specimens.