Garden PestsGarden Pests

““A Sure Thing”!A Sure Thing”!• Home Gardeners can tolerate a small Home Gardeners can tolerate a small

amount of pest damageamount of pest damage

• Less prone to infestationsLess prone to infestations

• Your income does not depend on Your income does not depend on maximum yieldsmaximum yields

Pest problemsPest problems• WeedsWeeds

• InsectsInsects

• DiseasesDiseases

• BirdsBirds

• AnimalsAnimals

• Other miscellaneousOther miscellaneous

PesticidePesticide• ““killer of pests”killer of pests”• Typically chemicalTypically chemical

– Benefits: rapid and complete controlBenefits: rapid and complete control– Problems: dangerous and can pollute the Problems: dangerous and can pollute the

environmentenvironment

• Pesticide Applicators Training Manual Pesticide Applicators Training Manual • Classes offered at UVMClasses offered at UVM• Contact Ann Hazelrigg 656-0493Contact Ann Hazelrigg 656-0493

Weeds !Weeds !• A plant out of place!A plant out of place!

• Growing where it is not wantedGrowing where it is not wanted

• Competes for:Competes for:– Space (esp. light)Space (esp. light)– WaterWater– NutrientsNutrients

• May harbor insects and diseaseMay harbor insects and disease

AllelopathyAllelopathy• “allelon” which means “of each other”,

and “pathos” which means “to suffer”

• chemical inhibition of one plant by chemical inhibition of one plant by anotheranother

• Noted for chickpea by Theophrastus (300 Noted for chickpea by Theophrastus (300 BC) and Pliny the Elder (1 AD)BC) and Pliny the Elder (1 AD)

Black Walnut Juglans nigraJuglans nigra produces juglandic acid produces juglandic acid

Not all allelopathy is bad!

• Rye and wheat when used as a cover crop suppressed the development of weeds

• Sorghum also has potent weed suppression chemicals.

Weeds !Weeds !• Weeds spread by seeds or rhizomesWeeds spread by seeds or rhizomes

• Weed seeds are long-livedWeed seeds are long-lived

• Most herbicides are generally NOT recommended Most herbicides are generally NOT recommended for use in a gardenfor use in a garden

Cultural control of weedsCultural control of weeds

• Plastic mulchesPlastic mulches - porous black plastic or - porous black plastic or clear plastic (to “cook” weeds) prior to clear plastic (to “cook” weeds) prior to plantingplanting

• Bark mulchBark mulch - to suppress weeds needs to - to suppress weeds needs to be 3” deep at least however, avoid be 3” deep at least however, avoid “cones” of mulch around the trunk of the “cones” of mulch around the trunk of the tree!tree!

Mulch “cone”Mulch “cone”

Rose plantfrozen during

winter

Cultural control of weedsCultural control of weeds

• Pull by hand Pull by hand

• Hand tools (hoes)Hand tools (hoes)

Burning weedsBurning weeds

Power equipmentPower equipment

Chemical control of weedsChemical control of weeds

• Herbicides = “killer of plants”Herbicides = “killer of plants”

• First developed in the 1930’sFirst developed in the 1930’s– Selective herbicidesSelective herbicides = kills only certain kinds = kills only certain kinds

of plantsof plants• Ex: 2,4-D kills only broad-leaved plantsEx: 2,4-D kills only broad-leaved plants

– Nonselective herbicidesNonselective herbicides = kills all plants it = kills all plants it contactscontacts

• Ex: RoundEx: Roundupup ®= Glyphosate ®= Glyphosate

Chemical control of weedsChemical control of weeds• Contact herbicideContact herbicide - injury to parts of the plant - injury to parts of the plant

the herbicide contacts the herbicide contacts

• Translocated herbicideTranslocated herbicide - chemical moves - chemical moves systemically through the vascular system of systemically through the vascular system of the plant (Ex: Roundthe plant (Ex: Roundupup ®) ®)

• Residual herbicideResidual herbicide - kills during and after - kills during and after applicationapplication

• Nonresidual herbicideNonresidual herbicide - kills only when the - kills only when the herbicide is appliedherbicide is applied

Chemical control of weedsChemical control of weeds

• Preplant herbicidePreplant herbicide - applied before the - applied before the crop is seededcrop is seeded

• Preemergent herbicidePreemergent herbicide - applied after the - applied after the crop is seeded but before it comes crop is seeded but before it comes through the soil surfacethrough the soil surface

• Postemergent herbicidePostemergent herbicide - applied after - applied after the crop has emergedthe crop has emerged

Chemical control of weedsChemical control of weeds

• Herbicides affected by:Herbicides affected by:– Soil texture (sand, silt, clay, OM)Soil texture (sand, silt, clay, OM)– Soil moistureSoil moisture– Light exposureLight exposure– All the above are important as to how they All the above are important as to how they

affect the soil microbes which often are affect the soil microbes which often are responsible for degrading the chemicalresponsible for degrading the chemical

– Herbicides persist longer on sandy, dry soilsHerbicides persist longer on sandy, dry soils

2,4-D damage to 2,4-D damage to broadleaf weedsbroadleaf weeds

Can kill shallow-rooted trees!Can kill shallow-rooted trees!Never apply if there is a breeze!Never apply if there is a breeze!

Garden plant injury from herbicidesGarden plant injury from herbicides

• Sensitive plants:Sensitive plants:– TomatoesTomatoes– GrapesGrapes– LilacsLilacs– MaplesMaples

• Symptoms:Symptoms:– Curling of leavesCurling of leaves– Light color of viens and leavesLight color of viens and leaves– Browning and death!Browning and death!

Herbicide injuryHerbicide injury

To avoid herbicide injuryTo avoid herbicide injury

• Spray when the air is stillSpray when the air is still

• Spray when it is cool (heat volatilizes Spray when it is cool (heat volatilizes chemicals)chemicals)

• Never use an herbicide sprayer for other Never use an herbicide sprayer for other spraying purposesspraying purposes

Biological weed controlBiological weed control

• One living organism used to control One living organism used to control anotheranother

• Little success with these methods so far Little success with these methods so far for general homeowner use.for general homeowner use.

Organic weed controlOrganic weed control

• A by-product from corn syrup production A by-product from corn syrup production seems promising. Sold by Gardens Aliveseems promising. Sold by Gardens Alive®® as as “WOW!“WOW!®® Plus”. Plus”. – a pre-emergent a pre-emergent

– a selective herbicide (only kills broadleaves weeds)a selective herbicide (only kills broadleaves weeds)

– can walk on it after appliedcan walk on it after applied

– can be used in the vegetable and flower garden on can be used in the vegetable and flower garden on establishedestablished plants plants