Neith LittleUrban Agriculture Educator
University of Maryland Extension, Baltimore CityIncludes slides adapted from presentation by Luke
Gustafson, Master Gardener Coordinator
INTEGRATED WEED MANAGEMENT
University of Maryland Extension programs are equal access
What is a weed?
Pragmatic definition: A plant out of place
Image credit: University of Nebraska Extension
University of Maryland Extension programs are equal access
What is a weed?
Ecological definition:
A species with “weedy” characteristics
Image credit: University of Illinois
University of Maryland Extension programs are equal access
University of Maryland Extension programs are equal access
University of Maryland Extension programs are equal access
1. Identify the plant
•Why bother? • Understand the plant
•Learn the weeds in your area
•Learn ID vocabulary• (opposite vs. alternate leaves,
etc.)
•Do not trust color•Books:
• p. 41 of your handbook• Weeds of the Northeast, by
Uva, Neal, and DiTomaso• Weeds of the South, by Bryson
and DeFeliceImage credits: Amazon.com
University of Maryland Extension programs are equal access
Leaf Arrangements
Opposite Alternate Whorled Basal
University of Maryland Extension programs are equal access
Simple Leaves
Entire Lobed Toothed
University of Maryland Extension programs are equal access
Simple Leaves
Internode
University of Maryland Extension programs are equal access
Compound Leaves
Pinnate
Even Pinnate
Odd Pinnate
Twice Pinnate or Bipinnate
LeafLeaf
Bud
Bud
University of Maryland Extension programs are equal access
Palmate
Compound Leaves
Palmate Trifoliate
University of Maryland Extension programs are equal access
Other terms
University of Maryland Extension programs are equal access
Dicot / broadleafMonocot / “grass”
Other terms
OchreaImage credit: Missouri State University
University of Maryland Extension programs are equal access
Other terms
Auricle
University of Maryland Extension programs are equal access
Ligules
Other terms
Auricle
University of Maryland Extension programs are equal access
Ligules
2. Understand the weed
Image credits: University of Minnesota, The Ohio State University University of Maryland Extension programs are equal access
Weed seed bank
Weed seeds can be dormant in soil for years• Goal: “draw down”
seed bank
• Germination stimulated by light, water, nutrients (“disturbance”)
Image credit: Oregon State University Seed Lab
University of Maryland Extension programs are equal access
Dispersal
University of Maryland Extension programs are equal access
Let’s practice
University of Maryland Extension programs are equal access
Let’s practice
University of Maryland Extension programs are equal access
• Cotyledon shape is• linear or “strap-like”
• First true leaf arrangement is
• Alternate• True leaf shape is
• Entire
• Pigweed, Amaranthusspp.
Image credit: Peter Smith, Ontario Ministry of Agriculture, Food, and Rural Affairs
Pigweeds, Amaranthus spp.
University of Maryland Extension programs are equal access
Image credit: Peter Smith, Ontario Ministry of Agriculture, Food, and Rural Affairs
Image credit: University of Illinois
• Heat-loving annual
• Grows fast• Produces a LOT
of seeds
Let’s practice
University of Maryland Extension programs are equal access
• Stem is• round
• Auricles are• Absent
• Ligule is• ENORMOUS, and
membranous
• Wild oat, Avena fatua
Image credit: Government of Manitoba
Pigweeds, Amaranthus spp.
University of Maryland Extension programs are equal access
Image credit: University of Illinois
• Wild oat, Avenafatua
• annual• Gyroscopic awns Image credit:
Government of Manitoba
Integrated weed management•Understand the plant
• Weed life strategies• Weed seed bank• Weed ID
•Understand weed management tools and build them in at multiple stages• The “many little hammers” of IPM
University of Maryland Extension programs are equal access
Management strategies
•Identify and understand the plant, control if necessary
•No silver bullets, just many little hammers
University of Maryland Extension programs are equal access
Image credit: Oregon State University Seed Lab
University of Maryland Extension programs are equal access
University of Maryland Extension programs are equal access
University of Maryland Extension programs are equal access
Physical barriers
https://www.youtube.com/watch?v=lx6WXjnO24Y
University of Maryland Extension programs are equal access
University of Maryland Extension programs are equal access
University of Maryland Extension programs are equal access
University of Maryland Extension programs are equal access
Photo by David Cappaert
University of Maryland Extension programs are equal access
University of Maryland Extension programs are equal access
University of Maryland Extension programs are equal access
• Some exploit disturbed habitat then decline over time
University of Maryland Extension programs are equal access
University of Maryland Extension programs are equal access
Photo from bugwood.org
University of Maryland Extension programs are equal access
Japanese barberry(Berberis thunbergii )
• From Japan
• Grows in difficult soils
• Sun to full shade
• Colorful leaves remain into late season
University of Maryland Extension programs are equal access
Japanese barberry(Berberis thunbergii )• Invades woodlands
• Spiny!
• Spreads by seed
University of Maryland Extension programs are equal access
Integrated weed management•Understand the plant
• Weed life strategies• Weed seed bank• Weed ID
•Understand weed management tools and build them in at multiple stages• The “many little hammers” of IPM
University of Maryland Extension programs are equal access
Integrated Weed ManagementWhat is a weed?What is a weed?Why control weeds?Weed Control Steps1. Identify the plantLeaf ArrangementsSlide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 152. Understand the weedWeed seed bankDispersalLet’s practiceLet’s practicePigweeds, Amaranthus spp.Let’s practicePigweeds, Amaranthus spp.Integrated weed managementManagement strategiesCulturalCulturalCulturalCulturalPhysical barriersMechanicalBiological ChemicalA little about invasive speciesInvasive SpeciesHow do invasives arrive?Cost of InvasivesWhy do species become invasive? Human influencesDisturbanceInvasive PlantsJapanese barberry�(Berberis thunbergii )Japanese barberry�(Berberis thunbergii )Integrated weed management