weeds for bees - Ohio State University · 2017-03-24 · Weeds Bees Love: weed biology, bee weed ID and which ones to leave alone Denise Ellsworth Ohio State University Department

Weeds Bees Love: weed biology, bee weed ID

and which ones to leave alone

Denise Ellsworth Ohio State University

Department of Entomology/Extension

Is it a weed?

Is it a weed? What is a Weed?

• A plant out of place and not intentionally sown

• A plant that grows where it is not wanted • A plant whose virtues have not yet been

discovered • A plant that is competitive, persistent,

pernicious, and interferes negatively with human activity

What Makes a Weed?Abundant seed production: Purslane: 52,000 seeds per plant

Rapid population establishment

Seed dormancy

– Resting stage

– May be affected by temperature, moisture, oxygen, light, chemical inhibitors, seed coat or immature embryos

– Weed control would be easy if not for dormancy

Long-term survival of buried seed

Dr. William Beal’s Experiments• 1884 – 1970 • Placed seeds of 20

weeds in pint bottles, buried 18” deep

• Removed every 5 years until 1920, then every 10 years

• Most seeds germinated after 10, several after 80 years!

Johnsongrass, 20 years

Adaptation for spread Vegetative propagation

Adapted to disturbed sites Benefits of Weeds?

Why Ohio is a Weed Hotspot… Ways to think about weeds…Invasive Weeds Noxious Weeds

Invasive Weeds

National Invasive Species Council: The term invasive species is defined as

“a species that is non-native to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health.”

Ornamental Pear, Pyrus calleryana

Noxious Weeds

The Plant Protection Act defines a noxious weed as “any plant or plant product that can directly or indirectly injure or cause damage to crops (including nursery stock or plant products), livestock, poultry, or other interests of agriculture, irrigation, navigation, the natural resources of the United States, the public health, or the environment.”

Noxious Weeds in Ohio• Shatter cane (Sorghum bicolor). • Russian thistle (Salsola Kali var. tenuifolia). • Johnsongrass (Sorghum halepense L. (Pers.)). • Wild parsnip (Pastinance sativa). • Wild carrot (Queen Annes lace) (Daucus carota L.). • Oxeye daisy (Chrysanthermum leucanthemum var. pinnatifidum). • Wild mustard (Brassica kaber var. pinnatifida). • Grapevines: when growing in groups of one hundred or more and not pruned,

sprayed, cultivated, or otherwise maintained for two consecutive years. • Canada thistle (Cirsium arvense L. (Scop.)). • Poison hemlock (Conium maculatum). • Cressleaf groundsel (Senecio glabellus). • Musk thistle (Carduus nutans). • Purple loosestrife (Lythrum salicaria). • Mile-A-Minute Weed (Polygonum perfoliatum). • Giant Hogweed (Heracleum mantegazzianum). • Apple of Peru (Nicandra physalodes). • Marestail (Conyza canadensis) • Canadian Horsetail (Erigeron canadensis)

Ways to think about weeds…Life CycleAnnuals:winter and summer

Biennials

Perennials:grasses, sedges, broadleaves

Woody Plants

Winter Annuals Summer Annuals

Biennials Perennials

Perennials Woody Plants

Red maple, Acer rubrum

Silver maple, Acer saccharinum Alder, Alnus spp.

Early Season Bees Willow, Salix spp.

Henbit and Purple deadnettle Birdsfoot trefoil, Lotus corniculatus

Dandelion, Taraxacum officinale Mustards, Brassica spp.

Apple and Crabapple, Malus spp. White clover, Trifolium repens

Red Clover, Trifolium pratense Bumble bee on common mallow, Image by Ariel Templeton

Catalpa

Black locust, Robinia pseudoacacia

Sweetclover, Melilotus spp. Rose-of-Sharon, Hibiscus syriacus

Are They Weeds?

Photos: Jennifer Hopwood, Mace Vaughan, MJ Hatfield

What butterflies need

Milkweed, Asclepias spp. Aster (Aster and Symphyrotrichum)

Specialist Andrena asteris on Symphyotrichum (Aster, with 7 specialist bees)

Specialist Melissodes denticulata on Vernonia

Joe-Pye weed, boneset & others Goldenrod, Solidago and Oligoneuron

Giant ragweed Goldenrod, Solidago: 11 specialist bees

The Worst Weeds

Autumn olive, Ealeagnus umbellata Honeysuckle, Lonicera spp.

Buckthorn, Rhamnus and Frangula Japanese knotweed, Fallopia japonica

Purple loosestrife, Lythrum salicaria Butterfly bush? Buddleia davidii

Dramatic effects can be achieved by layering an object over the same image with artistic effects

Denise Ellsworth

Program Director honey bee and

native pollinator education

Department of Entomology, OSU ExtensionThe Ohio State University

beelab.osu.edu [email protected]