This is an easy-to-use weed ID chart that shows conditions favouring them and what herbicide products can be used for their successful control. More product information is available in our turf protection section.
Herbicides are classified in several ways:
- pre-emergent or post-emergent
- contact or systemic and lastly
- selective or nonselective.
Pre-emergent herbicides are applied before weed emergence and act by killing weed seedlings as they germinate and try to emerge. In turf, they are mainly used against annual grass weeds such as Poa annua and summer grass, but there are also pre-emergent herbicides that are effective against many broadleaf weeds.
Contact and selective herbicides
Contact herbicides cause localized injury where the chemical comes in contact with the plant and work best when applied to young weeds. Examples including diquat, carfentrazone, plant oils, and herbicidal soaps. In contrast, systemic herbicides move within the plant, causing injury at additional sites in the plant, and can control older weeds. Examples include glyphosate, quinclorac, triclopyr, or 2,4-D, dicamba, and mecoprop mixtures (an active ingredient in many broadleaf weed killers).
Selective herbicides kill target weeds without damaging desirable turfgrass species and are toxic to only 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.
Weed ID Chart
Bindii, Bindi-eye, Bin-dii
Buttercup oxalis, Wood sorrel, soursob
Carrot weed, Common cotula, annual buttonweed
Catsear, Flatweed, False Dandelion
Creeping Mallow, marshmallow
Flaxleaf Fleabane, asthma weed.
Flickweed, Hairy bittercress
Lambs Tongue, Ribwort, Narrow plantain.
Onion Grass, Guildford Grass
Winter grass (Poa annua)
Tips to get the best results when controlling weeds.
- Correctly identifying them;
- A weed is only a weed when it is present where you don’t want it;
- Cultural control should always be at the front of mind. Dealing with the conditions favouring a weed will stop it from occurring in the first place;
- Always read the label and respective MSDS sheet on any turf protection chemical you are intending to use.
- Ensure that whatever chemicals you use are safe to use on your turf;
- Spot treating is always a good first step. A good idea is to use a marker dye to see where you have treated;
- In some situations when the weed population is too high you are looking at a blanket application;
- A selective post-emergent herbicide works best when weeds are actively growing. For example, applying a post-emergent herbicide in drought conditions will generally be unsuccessful;
- Certain post-emergent broadleaf herbicides, such as dicamba, can be absorbed by tree roots and may cause tree injury if applied too close to the tree drip line;
- The key to success for all pre-emergent herbicides is to apply the herbicide 2 to 3 weeks before weed germination;
- Pre-emergent herbicides work best when the soil is moist but the turf is dry at the time of application. They should also be thoroughly watered in as soon as possible after application;
- If you are applying pre-emergent herbicides, you cannot reseed for several weeks or months after application and finally
- It is much more difficult to control weedy grasses growing in turf with post-emergent herbicides.