A pre-emergent is a chemical that prevents seed from germinating or prevents seedlings from growing to maturity.

There are many different pre-emergent herbicides. Most are used on lawns to prevent weeds.

Synthetic chemical ingredients include benefin, isoxaben, pendimethalin, atrazine, dithiopyr, trifluralin and others.

The only organic pre-emergent available at this time is corn gluten meal.

It is key to apply the pre-emergent:

1. In early March to prevent summer weeds like goosegrass and crabgrass.

2. In mid-September, to prevent winter weeds like chickweed and annual bluegrass.

The pre-emergent must also be matched to the type of weed you want to control. Some pre-emergents control only grassy plants while others control only broad-leafed plants.

It is also important to be sure the product can be applied to the lawn grass you have.

The key to effective weed control is to first be sure you have identified the weed at hand and to read and follow the pesticide label exactly.