Low Impact Weed ControlMulches

Cheryl Wilen

Area IPM Advisor

UCCE/UC IPM

Stages for Weed Management

PlanningPreventionControlRestoration

Questions About Landscape Mulches

Is mulch the same as compost?

Is mulch the same as compost?

What is a mulch?

What is a mulch?

Do termites eat mulch?

How long do various mulches last?

What’s that stuff growing in my mulch?

How do they change soil?

Mulch A material that covers the soil surface. Shades the ground and physically hinders

germinating weed seedlings. Mechanical method of weed management

Selection of a specific mulch Characteristics

AvailabilityCostHow often it needs to be replenished

Non toxic to plantsEasy to applyFree from pathogens and weed seed Not a nitrogen drain

How to Choose

LOTS OF CHOICES!!Natural

Bark Grass clippings Leaf mold Manure Wood chips

Synthetic

Non-woven cloth

Plastic film Woven cloth

http://www.gardenplace.com/content/calculator/mulch_calc.html#

Search: Mulch calculator

Is Mulch the Same as Compost?

Mulch is a use. Compost is a process.

Benefits of Landscape Mulch Annual weed control Soil improvement

Prevents erosion Helps improve soil structure Improves water infiltration

Prevents water loss by evaporation

Soil ImprovementErosion Control

A thin layer of mulch on the soil surface reduces the washing away of soil particles by rushing water.

Mulches prevents raindrops from splashing on the soil surface.

Increases organic matter from breakdown

A mulch layer on the soil surface allows the soil to soak up more water.

Evaporation Reduction A 3-inch layer of

mulch on the soil surface dries much faster than the soil below it

This prevents water from moving into air.

Breakdown A 3-inch layer of mulch on the soil surface

keeps most annual weed seedlings from coming through.

Mulch settles and gradually rots Add additional layers

DISADVANTAGES OF MULCHING

Some mulches can cause a temporary, decrease in soil nitrogen

Some mulching practices are labor intensive

Bad mulches are “sour” and phytotoxic

May have insects, pathogens

No perennial weed control

More = Better

What’s that growing in my mulch?

Bird’s nest fungi

Slime molds

Mushrooms

Termites

Would subterranean termites survive on mulch?

Would subterranean termites eat mulch?

•Mulch provides better habitat than food•Should keep mulch about 18” away from wood structures

Note: probably not an issue for drywood termites

Fabric Mulches Fabric thickness affects the degree of weed

suppression. Prevents light penetration.

Rose Vigor(approx. 5 months after transplanting)

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Surflan 4

Gal+Sur (1+4)

Gal+ Sur(1+3)

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Biobarrier

T3201

T3401

Bark Mulch

Control

0=dead, 10=highly vigorous

Agricultural Mulch

Basic colors used (black, green, red) Black

Most widely used

Usually embossed for strength

Cheapest

Warms soil by contact

Plastic Films

Rubber Mulch - a "permanent" mulch that doesn't rot, dissolve into the ground or wash away from rain.

Made from recycled rubber truck tires, lasting ten years

PHYSICAL CONTROL OF PHYSICAL CONTROL OF PESTS: USE OF PESTS: USE OF MULCHESMULCHES

MULCHES MAY BE USED TO:

MANIPULATE TEMPERATURE

MANIPULATE LIGHT

MANIPULATE SOIL MOISTURE

OTHER EFFECTS

REDUCE INSECT FEEDING DAMAGE AND

TRANSMISSION OF DISEASES USING

REFLECTIVE MULCH

MODES OF MODES OF ACTION:ACTION:

•Light reflectionLight reflection

•Other?Other?

Insect Feeding Behavior

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Groundcover

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