Weed Management Around Fruit Crops

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Weed Management Around Fruit Crops

• Robert Tomesh, UWEX Hort. Spec.
• And Contributions from
• Jed Colquhoun, UWEX Weed Ecologist
• D.J. Heider, UWEX IPM Specialist

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Fruit Crop Weed Management

• Why control weeds
• Weed identification and management
• Anatomy of a weed
• Weed management strategies
• Cultural approaches
• Manual removal
• Chemical growth regulators

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What Is a Weed?

• Any plant that is a hazard, nuisance, or causes
  injury to man, his animals, or his desired crops.
  

Honeysuckle
Glossy Buckthorn
Dandelion
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Why Control Weeds?

• Competition light, water, nutrients, space
• Aesthetics

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Why Control Weeds?

• Allelopathy Release of compounds from one plant
  that are phyto-toxic to other plants

Black walnut Rye grass, barley, wheat Sorghum
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Why Control Weeds?

• Alternative Hosts Insects
  diseases
• Example fungal disease
• Early Blight on tomato

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Why Control Weeds?...Seeds

• Weed Seed Production Potential / Plant
• Redroot Pigweed 230,000
• Common Lambsquarter 38,000
• PA Smartweed 6,500
• Eastern Black Nightshade 40,000
• Green Foxtail 4,000
• Woolly Cupgrass 40,000

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Seed Longevity

• Many weed seeds have the potential to survive
  long periods in soil ---- dormancy

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Seed-bank Sampling

• Costly Time Consuming!
• Seedling Emergence Method

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Weed identification and management

• What makes a plant a weed?
• Who cares? Impacts of weed invasions
• Why do weeds always win? Biology of weeds
• Get to know the enemy weed ID
• Anatomy of a weed
• Common Wisconsin weeds
• Strategies for weed management
• Cultural strategies Reduce seed presences
• General techniques from manual removal to
  torches
• Strategies for herbicide use

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Why do weeds always win?

• Dormancy broken when conditions favor survival
• Rapid early growth and expansion
• Early and fast root growth and penetration of a
  large area
• Efficient uptake and processing of nutrients and
  water

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Why do weeds always win?

• Ability to reproduce early in life cycle
• Prolific seed production
• Absorb resources in excess
• Tolerate low levels of resources
• Genetic and environmental adaptability
• Ability to develop resistance to control measures

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Reproduction by seed

• First infestation is dependant on seed
• Seed production varies greatly
• Canada thistle 700 seeds per plant
• Small broomrape 1,000,000 seeds plant
• Seed longevity can be up to 1,000 years!

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Vegetative reproduction

• Less longevity in soil than seeds
• Very small structures can reproduce
• Canada thistle ¼ root results in new plant
• Can be as prolific as seed production
• Yellow nutsedge 1,900 new plants and 18,000
  tubers in one year from one plant

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Weed classification life cycles

• Annual
• Life cycle completed in one year
• Rely on seed production for species survival
• In general, easiest plant form to manage
• Examples common lambsquarter, redroot pigweed

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Weed classification life cycles

• Biennial
• Life cycle completed in two years
• Flowering and fruiting in second year
• Examples Canada thistle, field bindweed,
  quackgrass

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Perennial weed classification

• Simple perennials
• Spread by seed only, not vegetatively
• HOWEVER, vegetative structures can regenerate
  when injured or cut!
• Examples Canada thistle, field bindweed,
  quackgrass

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Weed identification goals

• The goal today is not to learn the thousands of
  weeds encountered in the Midwest
• The goal is to learn how to identify a weed
• Plant anatomy
• Plant keys
• Useful resources

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Anatomy of a weed grass seedlings
Source Hartmann et al. 1988. Plant Science
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Anatomy of a weed broadleaf seedlings
Source Hartmann et al. 1988. Plant Science
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Plant keys

• Start broad, narrow choices
• Series of yes/no questions take them one at a
  time, go back one step if necessary
• Double check answer with visual image, such as
  National Plants Database (http//plants.usda.gov/)

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Weed identification resources
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Integrated Weed Management

• Using all the available tools to manage weeds in
  an economical and environmentally safe manner
• tools
• Biological ify, Allelopathy
• Cultural
• Chemical

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3 best methods of weed control

• Prevention
• Prevention
• Prevention

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Ecological weed management is based on how a
plant is built

• Annual vs. biennial vs. perennial
• Growth stage perennials act like annuals for a
  short period
• Timing relative to the seasons
• Timing of chemical application and stage of weed
  growth

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Management timing relative to the seasons

• Perennial weed growth schedule
• Spring export carbohydrates from roots to new
  shoots
• Summer capture and assimilate new energy
• Fall pack it in for winter carbohydrates
  transported to the roots
• Winter usually, minimal growth or activity

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Management timing relative to the seasons

• Perennial weed management general terms
• Spring limit new growth drain the roots
  (cultivation, treflan)
• Summer prevent energy capture
• (cultivation, round-up)
• Fall opportunity to attack the root storage
  system (herbicides)
• Winter eliminate new seedlings
• (treflan, dacthal)

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Manual removal

• Success determined by population and distribution
  is it feasible?
• Annual weeds easily removed
• Perennial plants are often subdivided
• Vegetative root pieces often produce new plants

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Stale seedbed a fresh start

• Till soil to final seedbed
• Allow weeds to germinate (irrigate if necessary)
• Remove/control germinated weeds
• Manual removal
• In dry months, shut off water
• Herbicides
• Plant desirable species (minimal tillage)

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Solarization

• Clear polyethylene mulch traps solar energy
• Intense heat and sunlight required, often for
  about a month
• Weed seed cell structure is damaged and microbial
  degradation is high
• After solarization, mulch is removed

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Solarization

• Emergence of annual grass and broadleaf weeds can
  be reduced up to 99
• Effective only in upper soil layers
• Small-seeded weeds controlled better than
  large-seeded weeds
• Perennial weeds not controlled as well
• Moist soil traps heat better than dry soil

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Flame weeding

• Propane fueled burners for weed control
• Idea is not to burn off weeds, just break cell
  membranes (dark green color after flaming)
• Controls primarily young, emerged annual
  broadleaf weeds that have exposed growing points

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Flame weeding

• Grass and perennial weed control often poor, with
  re-growth after treatment
• Grass weeds growing point often below-ground
• Perennial weeds re-grow from root tissue
• Energy costs are high

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Organic Mulches

• Bark
• Straw
• Leaves
• Grass clippings
• Cocoa pods
• Wood Shavings
• or sawdust

• Concerns
• Introduction of pests
• Weeds
• Diseases?
• Rodents
• Fertility Issues

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Organic Mulches

• Fertilizer value of select mulches
• (based on dry weight)
• Mulch N P2O4 K2O
• Percent
• Alfalfa hay 2.45 0.50 2.10
• Oak leaves 1.49 0.00 0.00
• Grass hay 1.20 0.35 1.75
• Wheat straw 0.50 0.15 0.60
• Sawdust/wood 0.20 0.10 0.20
• shavings

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Organic Mulches
Carbon to nitrogen ratios (CN) of
mulches   Mulch CN ratio   Alfalf
a hay 121 Rotted manure 151 N Grass
clippings 191 Availability Tree
leaves 601 N Straw 801
Immobilization Sawdust/wood shavings 5001
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Synthetic Mulches

• Plastic
• colors several available, avoid clear
• conserve soil water
• warms soil
• UV light degradation
• Paper
• expensive
• biodegradable
• Fabric / Geo-textiles
• Perforated or woven
• Made of polypropylene

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Chemical Control

• Use as part of an IPM Program
• Always follow label
• Label legally binding document (must be
  followed explicitly)
• Only 4 legal ways to deviate from label
• Apply less than labeled amount
• Apply to any target pest not listed on label as
  long as site is listed
• Apply by any method not prohibited on the label
• Add fertilizer to the tank mix if not mentioned
  on label

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Chemical Control

• Potential problems
• Storage of unused product
• Re-entry intervals
• Plant-back restrictions
• Drift
• Tank contamination

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Label on the container
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Selectivity application and placement

• Pre vs. post herbicides
• Contact vs. translocated herbicides
• Soil placement

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Selectivity herbicide uptake
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Herbicide translocation
Water
Sugar
Nutrients
Amino acid
Xylem
Phloem
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Selectivity target site

• Absent in tolerant plants
• Altered in some herbicide resistant plants

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Growth regulatorsweeds controlled

• glyphosate (Roundup, etc.)
• 2,4-D, dicamba, MCPP broadleaf, annual weeds
• Triclopyr brush and broadleaf perennial weed
  control
• Postemergence, seedlings, shorter soil residual

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Herbicides Pre-emergent

• Soil (PRE) Applications
• Apply prior to weed emergence
• Rainfall or irrigation may be necessary for
  activation
• Apply to new transplants after soil has settled
• Apply granular products over dry foliage and not
  over herbaceous plants with whorls
• Potential for injury increases as temperature
  decreases

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Growth regulatorsplant systems involved

• Plant hormones chemical signals that coordinate
  plant activities
• germination
• growth
• reproduction
• death

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Pre-emergent Herbicides (systemic)

• Trifluralin (Preen, Preen n Green)
• Granular formulation available to home owners
• Easy to apply correct amount over a known area
• Must be activated with irrigation or rainfall (or
  lost to volatilization)
• Herbicide is taken up by roots of developing
  seedlings
• Inhibits root growth of emerging weeds
• Controls annual grasses and some broadleaves with
  some residual
• Labeled for use over a large number of plants

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Pre-emergent Herbicides (systemic)

• Eptam (Preen for Groundcovers)
• Granular formulation available to home owners
• Easy to apply correct amount over a known area
• Must be activated with irrigation or rainfall (or
  lost to volatilization)
• Herbicide is taken up by roots of developing
  seedlings
• Inhibits shoot growth of emerging weeds
• Controls annual grasses and some broadleaves
• Labeled for us in about 50 different groundcovers

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Pre-emergent Herbicides (systemic)

• Corn Gluten Meal
• Organic herbicide developed at Iowa State
• By-product of corn milling process in the
  production of corn starch
• Expensive
• Labeled on turf and shrubs
• Pre-emergent control of some grasses (including
  crabgrass) and broadleaves
• 10 nitrogen by weight

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Growth regulatorsmode of action
upset hormone balance disrupt cell enlargement
and cell division uneven or abnormal plant
growth plant death
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Herbicides

• Foliar (POST) Applications
• Apply to actively growing weeds
• Perennials generally require higher rates for
  control than annuals
• A surfactant may be required
• Always check rainfast requirements
• Potential for injury increases as temperature
  increases
• Label restricts harvest during year of
  application

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Growth regulatorsstrengths

• Economical
• Minimal resistance development
• Old standby, the kinks are worked out
• Broad spectrum broadleaf control

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Growth regulatorsweaknesses

• Established and perennial weeds can be difficult
  to control
• Drift and volatilization risks
• Persistence in compost

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Glyphosatestrengths

• Perennial weed control
• Non-selective, broad spectrum
• Relatively low toxicity concerns
• Limited soil residual

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Glyphosateweaknesses

• Non-selective kills or damages almost
  everything!
• No residual weed control
• Poor control in drought conditions
• Resistance development old tools dont work
  anymore

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Strawberry Weed Control in the Fruiting Years

• Annual grasses and quackgrass
• Fusilade after harvest or late fall
• Annual broadleaves and grasses
• Spring devrinol and dacthal
• Renovation gramoxone, sinbar
• Canada Thistle
• Roundup, spot treat (30 day harvest)

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Herbicide suggestions for woody plants (Read the
label for application timing and amounts)

• Pre-plant yearRound-up, Touchdown
• Planting year.Treflan, Surflan, Devrinol
• Fall of planting year.Princep, Simazine
• Producing years..Casoron, Devrinol, Princep
• Surflan, Preen, Treflan (Pre-emergent, weed free
  area)

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Fruit Crop Weed Management

• Why control weeds
• Weed identification and management
• Anatomy of a weed
• Weed management strategies
• Cultural approaches
• Manual removal
• Chemical growth regulators

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3 best methods of weed control

• Prevention
• Prevention
• Prevention