how can weed and crabgrass killer target said specific plants without damaging common types of grass?
In: Chemistry
One method is used on broadleaf weeds and another method on crabgrass.
Lawn grass has a narrow leaf. Lawn weeds such as dandelions are broad leaf. (Crabgrass is not a broadleaf.)
Broadleaf weeds absorb water through their leaves. Grass doesn’t. So, the herbicide used to combat broadleaf weeds is effective only on plants which absorb water though crabgrass. Broadleaf herbicides are actually growth hormones, which cause the plant to grow very quickly.
Crabgrass is a significant problem. Herbicides that kill crabgrass also kills lawns.
So, the usual plan to deal with crabgrass is to dig out the plants. Then, a pre-emergent herbicide is applied. The pre-emergent coats seeds and stops them from germinating. Most lawns have a perennial grass, and thus don’t rely on seeds for spreading.
The key to effective crabgrass control is to apply the pre-emergent at the correct time of the year.
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