How to Manage Pests

Types of plants affected

Selective herbicides

• Kill target plants (weeds) without damaging desirable turfgrass species
• Are toxic only to certain plants or weeds; for example, 2,4-D selectively kills only broadleaf plants and not grasses

Nonselective herbicides

• Kill all or most vegetation including turfgrass
• Should be used only prior to planting a lawn, during renovation, or as spot treatments

How herbicides injure a plant

Contact herbicides

• Cause localized injury where the chemical comes in contact with the plant
• Are most effective when applied to small young weeds

Systemic herbicides

• Move within the plant, causing injury throughout the plant
• Can control older weeds

When weeds are being controlled

Preemergent herbicides

• Are applied before weeds emerge from the soil
• Kill weed seedlings as they germinate and try to emerge
• Are primarily used against annual grass weeds such as crabgrass and annual bluegrass
• Are also effective against many broadleaf weeds

Postemergent herbicides

• Are applied after weeds have emerged from the soil
• Control actively growing weeds