MSU Extension Pesticide Education Ornamental Pest Management (Category 3B) Non-Pest Disorders and Landscape Weeds Chapter 5.

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Ornamental Pest Ornamental Pest Management (Category 3B)Management (Category 3B)

Non-Pest Disorders andNon-Pest Disorders and Landscape Weeds Landscape Weeds

Chapter 5Chapter 5

Environmental & Cultural Environmental & Cultural DisordersDisorders

Most landscape plant injury is caused by poor growing conditions.

Weakened plants are more susceptible to pest attack than non-stressed plants.

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Environmental and Cultural Environmental and Cultural DisordersDisorders

ConstructionConstruction Salt Salt DessicationDessication Mechanical Mechanical

damagedamage PesticidesPesticides CompactionCompaction

DroughtDrought FloodingFlooding Improper plantingImproper planting Improper cultural Improper cultural

practicespractices Poor plant Poor plant

selectionselection

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Tough environmental

conditions.

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Site too wet for this species.

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Tough environmental conditions.

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Poor planting technique.

Note the twine that has not decayed.

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Herbicide injury through root absorption.

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Black walnut trees and stunted white pine.

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Excavation and construction activity caused this tree to die early.

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Poor site conditions post-construction.

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Flooded conditions suffocate roots.

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Desiccation

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Cold temperature injury.

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Lightening injury on oak.

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Environmental and Cultural Environmental and Cultural DisordersDisorders

ConstructionConstruction Salt Salt DessicationDessication Mechanical Mechanical

damagedamage PesticidesPesticides CompactionCompaction

DroughtDrought FloodingFlooding Improper plantingImproper planting Improper cultural Improper cultural

practicespractices Poor plant Poor plant

selectionselection

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Landscape WeedLandscape Weed

WEEDWEED = any plant = any plant growing where it is not growing where it is not

wanted.wanted.

Change the location and any plant can become a weed.

For example, bluegrass invading a flower bed is a weed.

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Weeds Compete For:Weeds Compete For:

Growing spaceGrowing space

WaterWater

NutrientsNutrients

SunlightSunlight

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Knotweed is tolerant of compacted soil.

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Weeds are Indicators of Site Weeds are Indicators of Site ConditionsConditions

Hot soilHot soil– Purslane, spurgePurslane, spurge

Compacted, wetCompacted, wet– Annual bluegrassAnnual bluegrass

Wet, shadyWet, shady– Rough bluegrass, horsetailRough bluegrass, horsetail

Deep shadeDeep shade– Ground ivy, chickweedGround ivy, chickweed

Weeds can...

- Girdle plants

- Harbor pests

- Injure people

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Vines can girdle established plants.

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Monocots: parallel leaf veins, growth Monocots: parallel leaf veins, growth points at/below soil levelpoints at/below soil level– Grass family Grass family

• Crabgrass, quackgrassCrabgrass, quackgrass

– Sedge family Sedge family • NutsedgeNutsedge

– Lily familyLily family• Wild garlicWild garlic

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Dicots: net-like leaf veins, diverse growing Dicots: net-like leaf veins, diverse growing pointspoints– Composite family

• Dandelions, thistles

– Mustard family • Shepherd's purse

– Carrot family• Wild carrot

Many others

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Stages of Weed DevelopmentStages of Weed Development

1. Seedling1. Seedling

– Tender, vulnerableTender, vulnerable

2. Vegetative2. Vegetative

– Great uptake of Great uptake of water and nutrientswater and nutrients

3. Seed production3. Seed production

– Reduced uptake, energy Reduced uptake, energy directed to flowers, fruitdirected to flowers, fruit

4. Maturity4. Maturity

– Little uptake or energy Little uptake or energy production production

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Annual weeds: live one year Annual weeds: live one year – Summer annuals: Summer annuals: seed and die by winter.seed and die by winter.

• Pigweed, crabgrassPigweed, crabgrass

– Winter annuals: Winter annuals: germinate in late germinate in late summer, overwinter, produce seed, die the summer, overwinter, produce seed, die the next season.next season.

• Chickweed, pennycressChickweed, pennycress

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Lambsquarter

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Biennial weeds: broadleaf plants with Biennial weeds: broadleaf plants with a two year life cyclea two year life cycle

– vegetative growth first yearvegetative growth first year

– mature, seed and die in second yearmature, seed and die in second year

• Queen Anne’s lace, bull thistleQueen Anne’s lace, bull thistle

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Queen Anne’s lace.

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Perennial weeds: live 3 or more yearsPerennial weeds: live 3 or more years

– most persistent most persistent

– difficult to controldifficult to control

– propagulespropagules• rhizomes, stolons, bulbs, tubersrhizomes, stolons, bulbs, tubers

– wide range of dicots and monocotswide range of dicots and monocots• quackgrass, dandelion, poison ivyquackgrass, dandelion, poison ivy

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Quackgrass

Dandelion

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Scout, identify and inventory populations.

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Managing Landscape WeedsManaging Landscape Weeds

Maintain vigorous ornamentalsMaintain vigorous ornamentals

Prevent seed productionPrevent seed production

Prevent seed germinationPrevent seed germination

Limit emerged weeds earlyLimit emerged weeds early

Limit susceptible stages of mature Limit susceptible stages of mature weeds.weeds.

Alternative Weed ControlsAlternative Weed Controls

SanitationSanitation

TillageTillage

CultivationCultivation

CuttingCutting

MulchingMulching

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Chemical designed to control Chemical designed to control weeds. Plant, soil and weeds. Plant, soil and weather conditions influence weather conditions influence herbicidal activity.herbicidal activity.

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Herbicide Herbicide CharacteristicsCharacteristics

Contact Systemic

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Herbicide CharacteristicsHerbicide Characteristics

PersistentNon

Persistent

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Herbicide CharacteristicsHerbicide Characteristics

SelectiveNon

Selective

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Herbicide CharacteristicsHerbicide Characteristics Application in relation to plant developmentApplication in relation to plant development

– Pre-plantPre-plant

• Before crop is plantedBefore crop is planted

– Pre-emergentPre-emergent

• Before weeds emergeBefore weeds emerge

– Post emergentPost emergent• After weeds emergeAfter weeds emerge

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Herbicides and Plant Herbicides and Plant CharacteristicsCharacteristics

Growing pointsGrowing points

Leaf shape and orientationLeaf shape and orientation

Wax and cuticleWax and cuticle

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Herbicides and Plant Herbicides and Plant CharacteristicsCharacteristics

Leaf hairsLeaf hairs

DeactivationDeactivation

Life cycle stageLife cycle stage

Herbicide EffectivenessHerbicide Effectiveness

seedling vegetative flowering mature0

20

40

60

80

100

seedling vegetative flowering mature

% control

Climatic FactorsClimatic Factors

Relative humidityRelative humidity

LightLight

PrecipitationPrecipitation

TemperatureTemperature