Weed Management Flashcards
Weeds have the ability to…
invade, dominate and persist
What are the seed characteristics?
- Longevity of seeds(seed banks)
- Germination requirements filled in many environments
Vegetative Characteristics?
- Rapid growth(vegetative-flowering)
- Perennials with vigorous vegetative reproduction
- Perrenials not pulled from ground easily
- Competitive abilities(climbing, shade, drought, salt tolerant)
Reproductive Characteristics?
- Continuous seed production
- Cross pollination
- very high seed output
- adaptation for seed dispersal(wind, water, animals, machinary)
What parts of agriculture do weeds impact?
- crops
- livestock
- general farming
- rural population
Weed impacts on crops?
- yield reduction
- loss of yield
- reduced quality
- crop refusal
- increased transportation & production costs
- weed seeds/plant material cause heating in storage
- low tolerance for weed seeds(eliminate crop as certified seed source)
Weed impacts in livestock?
- reduced grazing area
- reduced forage production/quality
- effects milk/meat quality
- health issues
Weed impacts on general farming?
- Increased sanitation needs
- reduced ability to work soil
- limit management choices
- harbor other pests(diseases & insects can overwinter on vegetation)
- interfere with harvesting
Weed impacts on rural population?
- Use/spray drift concerns
- human health concerns
- drainage issues
- visibility at road crossings
- overall cost
What makes weeds successful? How?
Ability to interfere with growth of desirable plants
- Allelopathy
- Competition
- Parasitism
What are allelopathy plants?
Have the ability to release toxins in their root zone that interferes with the growth of other plants(rye)
what makes weeds competitive?
-based on timing of weed emergence (1st plant has the advantage) -weed density -growth habitat and rate -sexual reproduction -seed banks
In what 2 ways can weeds spread?
Artificial and natural agents
How do weeds spread by artificial agents?
- contamination seed/soil
- transport systems
- moving equipment
- clothes/belongings
- irrigation water
How do weeds spread by natural agents?
- wind/water
- animals, rodents, birds
- reproduces using vegetative structures
- allow for overwintering
- propagation
- extend parent plant to new sites
- grow faster than those from seed
- aid in survival after distribution
Types of weed distribution?
- patches
- outer field edges
- widespread, even distribution
- populations dependent on topography
Weed control/prevention of spread?
- use certified, weed-free seed
- prevent seed set
- practice roadside/fence line sanitation
- prevent spread
- avoid contamination feed/soil
- establish competitive crops
- integrate weed management
- avoid build-up of resistance
- ensure tillage operations aren’t spreading
- ensure tillage operations aren’t spreading the problem
Weed resistance?
- Multiple resistance wild oat and kochia are the top HR weed problems
- consistent applications of BMPs is the best long-term strategy
Top 5 weeds in MB?
- |Green foxtail
- wild buckwheat
- barnyard grass
- wild oat
- volunteer conola
What a summer annual?
1 growing season, fast growing with high seed return, seeds dormant over winter(Lambs quarters, green foxtail, redroot pigweed)
Possible Reduction- Less tillage
What a summer annual?
1 growing season, fast growing with high seed return, seeds dormant over winter(Lambs quarters, green foxtail, redroot pigweed)
Possible Reduction- Less tillage
What’s a winter annual?
Germinate late summer/fall, dorment winter, flowers in spring, sets seed and dies before summer heat(cleavers, shepherds purse, chickweed)
Possible Reduction-easiest to kill in fall before hardened or first thing spring
What’s a biennial?
Lives 2 years(Year 1-Vegetative, Year 2-Reproductive) Commonly found in reduced tillage sites and perennial forages(common burdock, white cockle)
Possible Reduction-spot spray, plant something to choke them out
What’s a perennial?
Grows many years, vary widely in how they spread, difficult to control, extremely competitive in annual crops often found in perennial forages
Reduction-fall systemic herbicide application for long-term control( moves through plant)
What’s a simple perennial?
Spread by seed
What’s a creeping perennial?
Rhizomes underground
Types of herbicide resistance?
- Herbicide tolerant(glyphosate-group 9-canola, corn,soybean)
- Glufosinate tolerant(group 10-canola, corn)
- Clearfield tolerant(group 2-canola)
Herbicide resistance development?
- begins with some individuals exhibiting natural resistance to the herbicide group
- repeated use that group applies selection pressure
- overtime resistance individuals survive and set seed resulting in resistant population getting larger
Resistant types?
-single resistance
-cross resistance(multiple herbicides, same mode of action)
-Multiple resistance(multiple herbicides, various modes of action)
-Group 1(grassy weeds, no broadleaf, ACCase inhibitor-attack growing point)
-Group 2(Most resistance broad leafed kochia(group 2, glyphosate)
Resistance-major problem group 1 & 2
How would you suspect herbicide resistant weeds?
- weeds still alive after spray
- weed increase, irregular shaped patch
- some dead, some alive after spray
- records show repeated herbicide use
How would you test for herbicide resistance?
-collect mature seeds, lab grows plants and sprays with herbicide group
What’s glyphosate resistant kochia?
-collect leaf material for DNA testing from top 2-3 inches of plant, bag it in plastic, put it on ice immediately after, keep all plants separated, send it to lab
What’s the Noxious Weed Act?
Provincial Legislation than give rural municipalities the power to manage weeds within there border.
What does the Noxious Weed Act entitle you to do?
By-law you have to destroy Tier 1 weeds by(burning, bagging)
Tier 1 weeds: waterhemp, palmer amaranth
