Knowing what weed control products to use and when to apply them will determine how effective they will be. Pre-emergent products will control most of your grassy weeds that reproduce by seed. Crabgrass, Goose grass and Foxtail are all examples of grassy weeds that are covered under most spectrums of pre-emergent products. It is important to understand that broadleaf weeds will not be stopped with the use of pre-emergent products that are labeled for grass control. Most broadleaf weeds will require the use of a selective broadleaf herbicide for their control. Note: If you are planning on seeding your lawn in the spring, be advised that pre-emergent products will negatively affect the growth of your lawn seed also.
Understanding weed control.
This spring we experienced warmer than normal temperatures with a faster than normal snow melt. Since we did not have a lot of snow this winter, spring arrived early for those of us living in the Cedar Rapids, Iowa City and Waterloo areas. With an early spring came the onset of early broadleaf weed infestation. While we were applying pre-emergent products to control crabgrass, we were met with lawns full of dandelions and other broadleaf weeds. This is the first year that we have had to treating our lawns for an abundant outbreak of broadleaf weeds in March. Since liquid broadleaf herbicides are a contact killer, only the weeds that were actively growing during the time of the application were eliminated. The active broadleaf weed pattern this spring lasted till about the middle of May when the weeds finally began to slow down.
Most granular broadleaf weed control products will not effectively control broadleaf weeds. Some liquid broadleaf weed control herbicides will still have a hard time tackling weeds such as creeping Charley and wild violets. The reason being is that the leaves of these plants tend to shed the herbicide product like an umbrella. A sticking agent in conjunction with a broadleaf weed control herbicide might be required to treat these tough weeds.