NonNon--Chemical Weed ControlChemical Weed Control•• This section will detail the methods of This section will detail the methods of

nonnon--chemical weed control. It will also chemical weed control. It will also define weed control and weed define weed control and weed management.management.

•• The five methods of weed control are:The five methods of weed control are:–– preventativepreventative–– culturalcultural–– mechanicalmechanical–– biologicalbiological–– chemicalchemical

Steps to Effective ManagementSteps to Effective Management

•• Monitor seed and vegetative populationsMonitor seed and vegetative populations•• identify problem weed speciesidentify problem weed species•• predict weed population shiftspredict weed population shifts•• decide whether control is needed or decide whether control is needed or

warrantedwarranted•• choose control technologychoose control technology•• consider grower/agency resources and needsconsider grower/agency resources and needs•• evaluate longevaluate long--term impacts, optionsterm impacts, options

Definition of Weed Definition of Weed ManagementManagement

•• System by which all available tools are System by which all available tools are used to reduce the weed used to reduce the weed seedbankseedbank, , prevent weed emergence with other prevent weed emergence with other plants and minimize competitionplants and minimize competition

•• OR OR -- use all methods in an integrated use all methods in an integrated approach to effectively manage weeds approach to effectively manage weeds in a short and long term approachin a short and long term approach

Preventative Weed Preventative Weed ManagementManagement

•• Definition Definition -- measures taken to prevent measures taken to prevent the introduction, establishment and/or the introduction, establishment and/or spread of specified weeds in nonspread of specified weeds in non--infested areasinfested areas

Federal Noxious Weed Act Federal Noxious Weed Act -- 19741974

•• ““any living stage (including, but not limited any living stage (including, but not limited to, seeds and reproductive parts) of any to, seeds and reproductive parts) of any parasitic or other plant, of a kind or parasitic or other plant, of a kind or subdivision of a kind, which is of foreign subdivision of a kind, which is of foreign origin, is new or can directly or indirectly origin, is new or can directly or indirectly injure crops or other useful plants, livestock, injure crops or other useful plants, livestock, poultry, or other interests of agriculture, poultry, or other interests of agriculture, including irrigation, or navigation, or fish or including irrigation, or navigation, or fish or wildlife resources of United States, or the wildlife resources of United States, or the public health.public health.””

Federal Noxious Weed ActFederal Noxious Weed Act

•• The main issues with this act are:The main issues with this act are:–– prevent entry of weeds of foreign prevent entry of weeds of foreign

originorigin–– establish and enforce quarantinesestablish and enforce quarantines–– control or eradication of weeds with control or eradication of weeds with

potential for great losspotential for great loss

Federal Seed Act Federal Seed Act -- 19391939

•• ““any weed or plant that is so declared any weed or plant that is so declared by an authoritative group, with the legal by an authoritative group, with the legal power to make such a declaration, to power to make such a declaration, to be harmful or possess noxious be harmful or possess noxious characteristicscharacteristics””

Federal Seed Act Federal Seed Act -- 19391939

•• Percentage of pure seed of the named Percentage of pure seed of the named cropcrop

•• percentage of other crop seedspercentage of other crop seeds•• percentage of weed seedspercentage of weed seeds•• the names of noxious weed seeds the names of noxious weed seeds

present and the rate of their present and the rate of their occurenceoccurence

Certified SeedCertified Seed•• One of the major aspects of the seed act is seed certification One of the major aspects of the seed act is seed certification

program. Notice how it lists the presence of 0.01% weed seedprogram. Notice how it lists the presence of 0.01% weed seed

QuarantinesQuarantines•• Isolate and prevent spread of noxious Isolate and prevent spread of noxious

weed speciesweed species–– examples include examples include witchweedwitchweed ((StrigaStriga sppspp.) .)

and tropical soda apple (and tropical soda apple (SolanumSolanum viarumviarum))–– effective example effective example -- StrigaStriga in North in North

Carolina, Carolina, CommelinaCommelina benghalensis in NCbenghalensis in NC

Steps in Weed PreventionSteps in Weed Prevention

•• Do not let weeds reproduce (kill prior to seed Do not let weeds reproduce (kill prior to seed set)set)

•• do not bury weed seed in do not bury weed seed in uninfesteduninfested areasareas•• do not plant infested crops or transplantsdo not plant infested crops or transplants•• do not feed weed screenings to livestockdo not feed weed screenings to livestock•• clean farm machinery when moved from one clean farm machinery when moved from one

site to the nextsite to the next•• kill weeds in surrounding areas kill weeds in surrounding areas -- ditchbanksditchbanks, ,

hedgerows, etc.hedgerows, etc.

Cultural Weed ManagementCultural Weed Management

•• Crop Rotation Crop Rotation -- prevent weed infestations prevent weed infestations of one or a few weeds DUE TO:of one or a few weeds DUE TO:–– differing planting and harvesting datesdiffering planting and harvesting dates–– differing competitive ability based on differing competitive ability based on

crop/weed maturity and growthcrop/weed maturity and growth–– differing fertility, water, etc.differing fertility, water, etc.–– monculturesmoncultures have typically greater weed have typically greater weed

infestations (example: wheat/infestations (example: wheat/sugarbeetsugarbeetrotation increased wheat yields by 79% over rotation increased wheat yields by 79% over wheat alone)wheat alone)

Planting DatePlanting Date

•• Rapid and even emergence of the crop Rapid and even emergence of the crop is critical to crop vigor and competitive is critical to crop vigor and competitive ability ability

•• planting a crop too early, when soil planting a crop too early, when soil temperatures too low, will often result temperatures too low, will often result in poor germination and low plant in poor germination and low plant population population –– this leaves open areas for this leaves open areas for weeds to invadeweeds to invade

Spatial ArrangementSpatial Arrangement

•• Reduced row spacing favors crop Reduced row spacing favors crop competitivenesscompetitiveness

•• Limitation in row crops is equipment for Limitation in row crops is equipment for planting, cultivation and harvestplanting, cultivation and harvest

•• Home gardens, plant as close together Home gardens, plant as close together as possible. However, tight spacing will as possible. However, tight spacing will often increase disease and insect often increase disease and insect pressure.pressure.

Spatial ArrangementSpatial Arrangement

•• Changing the planting pattern of Changing the planting pattern of peanuts has resulted in a reduction in peanuts has resulted in a reduction in weed pressureweed pressure

Single row spacingSingle row spacing

Twin row spacing Twin row spacing –– notice less weedsnotice less weeds

Seeding RateSeeding Rate•• Increased crop population will often Increased crop population will often

improve the competitive ability of the improve the competitive ability of the crop. However, need to worry about crop. However, need to worry about intraintra--specific (between the crop plants specific (between the crop plants themselves) competition.themselves) competition.

Cultivar DifferencesCultivar Differences

•• Some cultivars do better under weed Some cultivars do better under weed pressure than otherspressure than others–– corn corn –– late maturing varieties less late maturing varieties less

competitive than early maturingcompetitive than early maturing–– Wheat Wheat –– normal height varieties more normal height varieties more

competitive with weeds than semicompetitive with weeds than semi--dwarf. dwarf. SemiSemi--dwarf yield more, so chemical weed dwarf yield more, so chemical weed control is used to overcome the lower control is used to overcome the lower competitive abilitycompetitive ability

Cultivar DifferencesCultivar Differences

•• Dixie Runner peanut is an old variety Dixie Runner peanut is an old variety with a wide, spreading growth habit. It with a wide, spreading growth habit. It was replaced by was replaced by FlorunnerFlorunner and other and other higher yielding varieties. However, higher yielding varieties. However, when Dixie Runner was grown along when Dixie Runner was grown along side side FlorunnerFlorunner in competition with in competition with weeds, Dixie Runner outweeds, Dixie Runner out--yielded yielded FlorunnerFlorunner..

Soil FertilitySoil Fertility•• Species able to utilize soil nutrients will have Species able to utilize soil nutrients will have

a competitive advantagea competitive advantage–– Wild oat (Wild oat (AvenaAvena sppspp.) can take advantage .) can take advantage

of nitrogen earlier than wheatof nitrogen earlier than wheat–– Nitrogen and phosphorus amendments can Nitrogen and phosphorus amendments can

increase grassy weed infestationsincrease grassy weed infestations•• Low nitrogen in turf increases black Low nitrogen in turf increases black

medic and other legume weedsmedic and other legume weeds•• High nitrogen can increase annual High nitrogen can increase annual

bluegrass and chickweedbluegrass and chickweed

Soil FertilitySoil Fertility•• Fertilizer placement Fertilizer placement ––•• Research at the University of Florida Research at the University of Florida

showed you could reduce competition showed you could reduce competition for phosphorus by weeds by banding for phosphorus by weeds by banding fertilizer in the row as compared to fertilizer in the row as compared to broadcast applicationsbroadcast applications

Soil Fertility Soil Fertility -- pHpH•• Make sure the pH of the soil is adjusted Make sure the pH of the soil is adjusted

to meet the needs of the cropto meet the needs of the crop–– Most crops 6 to 6.5Most crops 6 to 6.5–– Range for optimum uptake of elementsRange for optimum uptake of elements

Weeds as IndicatorsWeeds as Indicators•• Low pHLow pH –– red sorrel (old timers used to red sorrel (old timers used to

call this weed call this weed sourweedsourweed, because it , because it indicated sour or poor ground)indicated sour or poor ground)

Weeds as IndicatorsWeeds as Indicators•• CompactionCompaction –– goosegrassgoosegrass and and plaintainplaintain

are good indicators of compacted soil. are good indicators of compacted soil. These species are generally observed These species are generally observed along the edges of driveways and cart along the edges of driveways and cart paths (remember the information on paths (remember the information on soil compression for seed germination?)soil compression for seed germination?)

Weeds as IndicatorsWeeds as Indicators•• Poor drainagePoor drainage

–– Sedges and pennywort (Sedges and pennywort (dollarweeddollarweed))–– Also rushes and Also rushes and alligatorweedalligatorweed

Weeds as IndicatorsWeeds as Indicators•• Low nitrogen Low nitrogen –– legumeslegumes

–– Remember that legumes fix their own nitrogen Remember that legumes fix their own nitrogen from the atmosphere, so they have an inherent from the atmosphere, so they have an inherent advantage over other species when nitrogen is advantage over other species when nitrogen is limiting. This also occurs when a high level of limiting. This also occurs when a high level of carbon is introduced into the soil (high C:N ratios). carbon is introduced into the soil (high C:N ratios). As the microbes begin to breakdown and utilize As the microbes begin to breakdown and utilize the carbon, they the carbon, they outcompeteoutcompete plants for all plants for all available nitrogen. Legumes that can fix their own available nitrogen. Legumes that can fix their own are not effected by the high C:N ratio.are not effected by the high C:N ratio.

Weeds as IndicatorsWeeds as Indicators•• High pH High pH –– plaintainsplaintains

VoidsVoids

•• A void is an open area that invites A void is an open area that invites weeds, more of an issue with turf and weeds, more of an issue with turf and ornamental plantingsornamental plantings

•• Also an issue with perennial forages Also an issue with perennial forages and natural areasand natural areas

•• Can also be considered an issue with Can also be considered an issue with NOT achieving a proper stand in an NOT achieving a proper stand in an agronomic or horticultural cropagronomic or horticultural crop

Natural Reasons for VoidsNatural Reasons for Voids

•• Environmental stress Environmental stress –– flooding, hail, flooding, hail, drought, lightning, hurricanesdrought, lightning, hurricanes

•• Animals Animals –– herbivoryherbivory (wild hogs)(wild hogs)•• Diseases, insects, nematodesDiseases, insects, nematodes

Management Reasons for VoidsManagement Reasons for Voids

•• Improper mowing Improper mowing –– height, frequencyheight, frequency•• Improper fertilityImproper fertility•• Improper irrigationImproper irrigation•• Lack of core cultivationLack of core cultivation•• Lack of thatch managementLack of thatch management•• Lack of traffic control (compaction)Lack of traffic control (compaction)

Weed Management Strategy Weed Management Strategy -- II

•• Summer grasses Summer grasses –– crabgrass, crabgrass, goosegrassgoosegrass•• Keep in mind crabgrass germinates at 55F, Keep in mind crabgrass germinates at 55F,

goosegrassgoosegrass 65F, tropical 65F, tropical signalgrasssignalgrass 70F70F•• timing is critical to reduce problemstiming is critical to reduce problems

–– Avoid establishment at the time of grass germinationAvoid establishment at the time of grass germination–– Avoid Avoid verticuttingverticutting or core cultivation at the time of or core cultivation at the time of

germinationgermination–– Lower mowing height when grass is setting seed or Lower mowing height when grass is setting seed or

collect clippingscollect clippings–– Relieve soil compaction to increase turf competitiveness Relieve soil compaction to increase turf competitiveness

with with goosegrassgoosegrass–– Apply preApply pre--emergence herbicides before germination emergence herbicides before germination

temperatures are reachedtemperatures are reached

Weed Management Strategy Weed Management Strategy -- IIII

•• Winter grasses Winter grasses –– annual bluegrassannual bluegrass•• This species germinates <60FThis species germinates <60F

–– Species most competitive with close Species most competitive with close mowing, high water, high nitrogenmowing, high water, high nitrogen

–– Correct drainage, raise mowing heightCorrect drainage, raise mowing height–– Avoid cultivation at germination tempsAvoid cultivation at germination temps–– Collect clippings at time of high seed Collect clippings at time of high seed

productionproduction

Weed Management Strategy Weed Management Strategy -- IIIIII

•• Perennial weeds in turfPerennial weeds in turf–– Maintain dense turf through proper fertility, Maintain dense turf through proper fertility,

proper mowing, insect & disease controlproper mowing, insect & disease control–– Spot treat or physically remove isolated Spot treat or physically remove isolated

patchespatches–– Apply postemergence herbicides in the fall Apply postemergence herbicides in the fall

to maximize controlto maximize control

Biological Weed ManagementBiological Weed Management

•• This type of control tries to induce mortality This type of control tries to induce mortality factors into the population to establish a new factors into the population to establish a new equilibriumequilibrium

•• I.e. I.e. –– establish a ecological cycle to lower establish a ecological cycle to lower numbersnumbers

•• Objective Objective –– formally abundant organism formally abundant organism (weed) has been reduced to a rare species (weed) has been reduced to a rare species which is attacked by rare enemieswhich is attacked by rare enemies

Ecological vs. appliedEcological vs. applied•• EcologicalEcological is the action of parasites, is the action of parasites,

predators or pathogens that maintain predators or pathogens that maintain another organismanother organism’’s population density s population density at stable (acceptable) levels. Introduce at stable (acceptable) levels. Introduce the species and they maintain their the species and they maintain their population while reducing/maintaining population while reducing/maintaining the weed (once put in place, there is no the weed (once put in place, there is no further intervention)further intervention)

AlligatorweedAlligatorweed•• During the 1950During the 1950’’s and 60s and 60’’s s alligatorweedalligatorweed was was

a major problem in Florida. In the early 60a major problem in Florida. In the early 60’’s s a flea beetle (a flea beetle (AgasiclesAgasicles hydrophilahydrophila) was ) was introduced for control. Since its introduction, introduced for control. Since its introduction, this flea beetle cycles with the plant, keeping this flea beetle cycles with the plant, keeping alligatorweedalligatorweed suppressed in natural areas suppressed in natural areas such that no further control measures are such that no further control measures are needed. A good example of ecological needed. A good example of ecological control.control.

Ecological vs. appliedEcological vs. applied•• AppliedApplied is the continual introduction of is the continual introduction of

parasites, predators, or pathogens to parasites, predators, or pathogens to suppress a weed populationsuppress a weed population

•• Some can be considered Some can be considered mycoherbicidesmycoherbicides (fungal pathogens)(fungal pathogens)

•• The population of the organism cannot The population of the organism cannot maintain itself and therefore must be maintain itself and therefore must be continuously introducedcontinuously introduced

History of BioHistory of Bio--ControlControl•• Been used for centuries for insects Been used for centuries for insects ––

praying mantis, spiders, ladybugspraying mantis, spiders, ladybugs•• Has also been used for weeds but less Has also been used for weeds but less

well documented and often considered well documented and often considered normal agronomic practicesnormal agronomic practices

Prickly Pear CactusPrickly Pear Cactus•• This species is native to the U.S. and was This species is native to the U.S. and was

introduced into Australia in the 1920introduced into Australia in the 1920’’s for the s for the edible fruit. However, prickly pear quickly edible fruit. However, prickly pear quickly spread and covered over 1 million hectares. A spread and covered over 1 million hectares. A moth borermoth borer ((CactoblastisCactoblastis cactorumcactorum) from ) from South America was introduced and rapidly South America was introduced and rapidly controlled this species. Conversely, the moth controlled this species. Conversely, the moth was accidentally introduced into the U.S. and was accidentally introduced into the U.S. and now threatens many native cacti.now threatens many native cacti.

Other ExamplesOther Examples•• Water lettuce Water lettuce –– several insect introductionsseveral insect introductions•• Water hyacinth Water hyacinth –– several insectsseveral insects•• Northern Northern jointvetchjointvetch –– ((ColletotrichumColletotrichum

gloeosporioidegloeosporioide) COLLEGO was the trade ) COLLEGO was the trade name of the name of the mycoherbicidemycoherbicide developed using developed using this pathogen. This is for control of this pathogen. This is for control of joiintvetchjoiintvetchin rice.in rice.

•• Musk thistle Musk thistle –– controlled by controlled by RhinocyllusRhinocyllusconicosconicos -- beetlebeetle

Grass CarpGrass Carp•• This form of This form of biocontrolbiocontrol is extremely is extremely

controversial for aquatic weed controversial for aquatic weed management. The following website management. The following website details why.details why.

•• http://http://plants.ifas.ufl.edu/guide/grasscarp.plants.ifas.ufl.edu/guide/grasscarp.htmlhtml

MelaleucaMelaleuca•• http://tame.ifas.ufl.edu/index.htmhttp://tame.ifas.ufl.edu/index.htm --

gives a great overview of the problemgives a great overview of the problem•• This site This site --

((http://tame.ifas.ufl.edu/html/managemhttp://tame.ifas.ufl.edu/html/management/biological.htment/biological.htm) gives a description ) gives a description of the of the biocontrolbiocontrol aspect and how its aspect and how its working.working.

BiocontrolBiocontrol DefinitionsDefinitions•• ParasiteParasite –– a species that lives in or on a a species that lives in or on a

larger host (generally), feeding upon it larger host (generally), feeding upon it and frequently destroying it (leeches, and frequently destroying it (leeches, lamprey eels)lamprey eels)

•• ParasitoidParasitoid –– an insect which is only an insect which is only parasitic in its immature stages and will parasitic in its immature stages and will destroy the host in the process of destroy the host in the process of development (spider wasps)development (spider wasps)

BiocontrolBiocontrol DefinitionsDefinitions•• PredatorPredator –– an animal which feeds upon an animal which feeds upon

other organisms (herbivores such as other organisms (herbivores such as grass carp, sheep, goats, cattle, etc.)grass carp, sheep, goats, cattle, etc.)

•• PathogensPathogens –– a microa micro--organism that organism that causes diseases in a target speciescauses diseases in a target species

Characteristics of a Good Characteristics of a Good Biological SystemBiological System

•• HostHost--specific, or other nonspecific, or other non--important host important host species that will support the biological species species that will support the biological species (in other words, what is the species going to (in other words, what is the species going to eat if the target weed dies during the eat if the target weed dies during the winter?)winter?)

•• Effective in control, reducing the target Effective in control, reducing the target species to nonspecies to non--harmful levelsharmful levels

•• Favorable hostFavorable host--plant synchronization with the plant synchronization with the natural enemies life cyclenatural enemies life cycle

•• Be prolific and thrive in widespread areas (all Be prolific and thrive in widespread areas (all areas that include the weed)areas that include the weed)

•• Good colonizersGood colonizers

Where Do Where Do BiocontrolsBiocontrols Fit?Fit?

•• Perennial crops, low input cropping Perennial crops, low input cropping systemssystems

•• Rapid control not necessaryRapid control not necessary•• Complete control not neededComplete control not needed•• Monoculture of one target weedMonoculture of one target weed•• Natural ecosystems are ideal situationsNatural ecosystems are ideal situations

Where Do Where Do BiocontrolsBiocontrols NOTNOT Fit?Fit?

•• Most row crop and aesthetic turf situationsMost row crop and aesthetic turf situations–– Damage is seen before control can be effectiveDamage is seen before control can be effective–– Remember in row crops there is more than one Remember in row crops there is more than one

weed, so you would need a weed, so you would need a biocontrolbiocontrol agent for agent for each weedeach weed

–– Since Since biocontrolbiocontrol depends on leaving some of the depends on leaving some of the plant, this level of control is not acceptable for plant, this level of control is not acceptable for most turf situationsmost turf situations

TimeTime--Lag of Lag of BiocontrolBiocontrol

TimeTime--Lag of Lag of BiocontrolBiocontrol•• In the previous slide, notice how the growth of the crop is In the previous slide, notice how the growth of the crop is

compromised due to the competitiveness of the weed. compromised due to the competitiveness of the weed. The The biocontrolbiocontrol is introduced at 4 weeks to allow for is introduced at 4 weeks to allow for enough weed biomass to sustain growth of the agent. It enough weed biomass to sustain growth of the agent. It takes time for the agent to build up sufficient numbers to takes time for the agent to build up sufficient numbers to decrease plant growth. This occurs at 10 weeks (this is decrease plant growth. This occurs at 10 weeks (this is where a second line is drawn to show the separation where a second line is drawn to show the separation between crop growth with and without between crop growth with and without biocontrolbiocontrol agent). agent). However, the damage to the crop has already occurred. However, the damage to the crop has already occurred. Remember from previous material that the impact of Remember from previous material that the impact of weeds is greatest in early season. Even though the weed weeds is greatest in early season. Even though the weed is controlled by the is controlled by the biocontrolbiocontrol agent, the weed has caused agent, the weed has caused sufficient damage to the crop.sufficient damage to the crop.

Mechanical ControlMechanical Control•• This is probably one of the oldest forms This is probably one of the oldest forms

of weed control practiced and is still of weed control practiced and is still widely used today. Anything that uses widely used today. Anything that uses or employs a physical force to control or employs a physical force to control weeds is considered mechanical control. weeds is considered mechanical control. This includes mulches (physical barrier), This includes mulches (physical barrier), burning, flooding, as well as tillage, burning, flooding, as well as tillage, cultivation and mowing.cultivation and mowing.

Weeding By HandWeeding By Hand•• Hand pullingHand pulling•• HoeingHoeing•• Variety of garden tools and gadgetsVariety of garden tools and gadgets•• Still the primary method in underStill the primary method in under--developed countriesdeveloped countries•• Expensive due to labor costs and time involvedExpensive due to labor costs and time involved•• However However –– highly selective and often the only method. highly selective and often the only method.

Hand weeding is still used in many vegetable Hand weeding is still used in many vegetable operations operations -- $500 to 900 per acre.$500 to 900 per acre.

Hand Tillage Hand Tillage –– Growing Growing Peanuts in Guyana, S.A.Peanuts in Guyana, S.A.

Tillage Tillage -- AdvantagesAdvantages•• Primary reason for tillage is weed Primary reason for tillage is weed

controlcontrol–– Breaks weeds apart, pulls from soilBreaks weeds apart, pulls from soil–– Causes desiccationCauses desiccation–– Exhausts food reservesExhausts food reserves–– Reduces seed and/or vegetative Reduces seed and/or vegetative propagulepropagule

bankbank

Tillage Tillage -- DisadvantagesDisadvantages•• Exposes soil to wind and water erosionExposes soil to wind and water erosion•• Buries weed seed, ensures survival through Buries weed seed, ensures survival through

dormancydormancy•• Deep tillage can bring buried weed seeds to Deep tillage can bring buried weed seeds to

the surfacethe surface•• Damage crop rootsDamage crop roots•• Causes soil compactionCauses soil compaction•• To effectively control weeds, several tillage To effectively control weeds, several tillage

operations must be performed operations must be performed -- $$$$$$$$

Tillage OperationsTillage OperationsConventional PlantingConventional Planting

•• Break ground with a moldboard plowBreak ground with a moldboard plow•• Break up clods with disk harrowBreak up clods with disk harrow•• Spring tooth harrow 2X to prepare a Spring tooth harrow 2X to prepare a

smooth seedbedsmooth seedbed•• PlantPlant•• Cultivation Cultivation –– 2 to 4 times, depending on 2 to 4 times, depending on

cropcrop

Tillage OperationsTillage OperationsConservation PlantingConservation Planting

•• Plant directly into previous crop residuePlant directly into previous crop residue•• OR deep chisel plowing followed by OR deep chisel plowing followed by

direct plantingdirect planting•• OR tillage in a small strip, then plant OR tillage in a small strip, then plant

directly in that small stripdirectly in that small strip

CultivationCultivation•• Basically Basically –– in row tillagein row tillage•• Plant crops in parallel rows and use Plant crops in parallel rows and use

tillage to keep the middles cleantillage to keep the middles clean

MowingMowing•• Selective removal of the apical Selective removal of the apical meristemmeristem

–– Causes plant deathCauses plant death–– Eliminates seed productionEliminates seed production–– Depletion of reservesDepletion of reserves

•• May change an upright plant to a prostrateMay change an upright plant to a prostrate•• Weakens weeds, allows grasses to Weakens weeds, allows grasses to outcompeteoutcompete•• Perennial weeds will require more Perennial weeds will require more mowingsmowings for for

complete controlcomplete control•• Frequency and cutting height are criticalFrequency and cutting height are critical

Types of MowersTypes of Mowers•• Depends on the outcome of the grass Depends on the outcome of the grass ––

fine vs. rough turf, forage vs. pasturefine vs. rough turf, forage vs. pasture•• SicklebarSicklebar•• FlailFlail•• ReelReel•• RotaryRotary

Large EquipmentLarge Equipment•• Brush and woody plant control, Brush and woody plant control,

generally expensive, longgenerally expensive, long--term control, term control, need to spread out over several yearsneed to spread out over several years

•• Used on open range in central Florida Used on open range in central Florida for cattle grazingfor cattle grazing

•• Also used for invasive plant control Also used for invasive plant control ––Brazilian pepper, Brazilian pepper, MelaleucaMelaleuca, Old, Old--World World climbing fernclimbing fern

Types of Large EquipmentTypes of Large Equipment

•• BulldozersBulldozers•• Chaining Chaining –– large anchor chains (80 lbs each) large anchor chains (80 lbs each)

are dragged between two dozersare dragged between two dozers•• Roller chopping Roller chopping –– large steel drums with large steel drums with

cutter bars, filled with water or concretecutter bars, filled with water or concrete•• Web plow Web plow –– mounted to a road grader, large mounted to a road grader, large

blade that runs underground to shear off blade that runs underground to shear off roots of large woody plantsroots of large woody plants

MulchesMulches•• Used to exclude light, preventing growthUsed to exclude light, preventing growth•• Limited to small acreage, logistics, $$Limited to small acreage, logistics, $$•• Limited to transplants or specialized seedingLimited to transplants or specialized seeding•• Poor control of Poor control of nutsedgenutsedge ((CyperusCyperus rotundusrotundus, C. , C.

esculentusesculentus), over time perennial weeds are not ), over time perennial weeds are not controlled, begin to grow through mulchcontrolled, begin to grow through mulch

•• In crop production will need specialized irrigation In crop production will need specialized irrigation ––drip irrigation buried under the plasticdrip irrigation buried under the plastic

•• In crop production, disposal of the plastic is also a In crop production, disposal of the plastic is also a major problemmajor problem

•• THERE IS NO SUCH THING AS A PERMANENT THERE IS NO SUCH THING AS A PERMANENT MULCH! EXCEPT MAYBE ASPHALT OR CONCRETEMULCH! EXCEPT MAYBE ASPHALT OR CONCRETE

Mulches Mulches -- TypesTypes•• OrganicOrganic

–– Straw, wood chips, pine bark, sawdustStraw, wood chips, pine bark, sawdust

•• InorganicInorganic–– Rock, gravel, etc.Rock, gravel, etc.

•• SyntheticSynthetic–– Black plasticBlack plastic–– NewspaperNewspaper–– Cloth fiberCloth fiber

•• Cost, applicability, duration are the deciding Cost, applicability, duration are the deciding factorsfactors

FloodingFlooding

•• Used for weed control in rice for Used for weed control in rice for centuriescenturies–– Shift in species/weed spectrumShift in species/weed spectrum

•• Opposite of flooding is drawdown, Opposite of flooding is drawdown, which is used for aquatic weed control. which is used for aquatic weed control. Drain the water body, allow the weeds Drain the water body, allow the weeds to desiccate, then reto desiccate, then re--fillfill

FireFire•• Practiced for centuries Practiced for centuries

–– native Americans were thought to have burned native Americans were thought to have burned the great plains to maintain grasses for buffalo the great plains to maintain grasses for buffalo grazinggrazing

–– Also part of many ecosystems (Also part of many ecosystems (pyrogenicpyrogenic species)species)

•• Mechanized flame cultivation in cottonMechanized flame cultivation in cotton•• HandHand--held flame wands for selective weed held flame wands for selective weed

controlcontrol•• Flame throwers for weed control along Flame throwers for weed control along

ditchbanksditchbanks, etc., etc.

Other Types of MechanicalOther Types of Mechanical

•• Heat Heat –– steam used to heat the soil and steam used to heat the soil and kill weed seeds, sterilizationkill weed seeds, sterilization

•• MicrowaveMicrowave•• These units are huge, expensive and These units are huge, expensive and

slow slow –– not really usednot really used