Mulching and Weed Control

8/12/2019 Mulching and Weed Control

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Mulching and Weed Control

Jennifer JensenExtension Educator


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WEEDS, WEEDS, WEEDSWeeds are frequently cited as the most challenging

pest problem in both organic and non organic gardens.


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What is a weed?A plant that is out of place and/or has the wrong

timing.

A plant considered undesirable, unattractive, ortroublesome, especially one growing where it is notwanted, as in a garden.


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What weeds are in your garden?


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Weed Control Pre emergent controlling weeds before the crop

emerges

Pre emergent Herbicide - one that generally controlsungerminated seeds

Post emergent after crop has emerged

Post emergent Herbicide one that generally controlsemerged plants


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Weed Control Exclusion

Elimination

Prevent Establishment

Removal

Amelioration

USDA National OrganicProgram Standards

Crop pests, weeds, and diseases

will be controlled primarilythrough management practicesincluding physical, mechanical,and biological controls

When these practices are notsufficient, a biological,botanical, or synthetic substanceapproved for use on the NationalList may be used


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Weed Control Solarization

Hand Weeding

Mulches Herbicides

Organic Herbicides

Flame Weeding

Steam and Hot Water


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Solarization Till soil

Moisten

Place clear plastic


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Hand Weeding Hand weeding and

cultivation are the most

important weedmanagement options inthe home garden andlandscape plantings

and should be includedin all weedmanagement programs.


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Flame Weeding Stale Seedbed Technique

Till up planting area, then wait for weed seeds togerminate before you flame weed, then plant seeds ortransplants

Peak Emergence Technique

Till up planting area, plant seeds, flame weed just beforevegetable seedlings emerge.


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Steam and Hot Water Weed Control High temperature water provides a form of thermal weed

control without the danger of an open f lame in arid

regions.


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Organic Herbicide USDA National Organic Program has The National

List of Allowed and Prohibited Substances

Herbicides, soap-based For use in farmstead maintenance (roadways, ditches, right of

ways) and ornamental crops.

Mulches Newspaper or other recycles paper, without glossy or colored inks

Plastic mulch and covers (petroleum-based other than polyvinylchloride (PVC))

Organic Materials Review Institute (OMRI) The OMRI listing does not imply product approval by any federal

or state government agency. It is the user's responsibility todetermine the compliance of a particular product.


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Organic Herbicides Corn Gluten

Use as pre-emergent

Reduces seedgermination

Does not affecttransplants or lawns


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Organic HerbicidesVinegar

10-20% Strength

Household is 5%

Can cause burns and eyedamage


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MulchesAluminum Foil or Aluminum Painted Mulch

Plastic Mulches

Degradable Mulches Organic Mulches


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Aluminum Mulches


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Aluminum MulchesAdvantages

Increased yields for numerous vegetable cropscompared to bare soil (more noticeable increases inyears with less-than-adequate rainfall).

In most studies, aluminum mulches repelled aphidsand thrips.

The reflecting light on the undersides of leaves mayrepel the aphids.

When vector insects are repelled, transmission ofviruses is also reduces.


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Aluminum MulchesDisadvantages

Experimented with as early as the 1950s, but wasfound not to be economical on a large scale.

Hard to lay

Expensive

Sometimes caused physical damage to the plants that

came in contact with it.


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Plastic Mulches


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Plastic MulchesAdvantages

Black plastic can warm the soil 4-5oF and eliminateweed problems since light transmission is drasticallyreduced.

Red mulch has been shown to increase early tomatoyields, but not overall yields in all studies.


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Plastic MulchesDisadvantages

Some insects like aphids, thrips, and whiteflies may beattracted to black plastic.

Influence of mulch color on crops is highly specificand may vary with plant type, climate, seasonalconditions, etc.

Shredded newspaper had better weed control thanhay, but news paper sheets did not.


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Paper Mulches


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Paper MulchesAdvantages

Paper mulches were used in the first half of thecentury, before plastics were developed.

Can be turned into soil at end of season

Renewable resource that would otherwise end up inlandfill.


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Paper MulchesDisadvantages

Paper mulches may degrade too quickly (this may beadvantageous for some purposes).

Tend to degrade early especially around edges that areheld down with soil.

Windy conditions hinder complicate installation.

Mixed results in terms of yields


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Organic Mulches


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Organic MulchesAdvantages

Can be incorporated in to the soil at the end of theseason as a soil amendment

Materials too high in carbon may tie up nitrogen in soil,but in the long run may add immobilized organicnitrogen and increase the ability of the soil to hold on toother nutrients

May help increase water-holding capacity of soil


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Organic MulchesDisadvantages

Tend to keep soil cooler, which can delay early seasongrowth.

Some studies have found that organic mulches arecost-effective in increasing yields or controllinginsects.


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Mulching and Weed Control