by Pamm Cooper, Lawn Educator
Many lawns suffered some stress and even may have died out in areas due to the drought last year. Unless new turf grass is established, crabgrass and other weeds will come in where the lawn grass used to be. The trick is to establish the new grass in a very small window of time before the crabgrass seeds dropped last summer germinate and crowd out desirable grasses.
By now, an herbicide barrier should have been put down to prevent any crabgrass from germinating or surviving the seedling stage. But if the desirable grass has not already started to get established from seed, it is too late to try and seed it if an herbicide to prevent crabgrass has been put down. A preventative pre-emergent control will stop any grass from germinating, not just crabgrass. If you have already put down the pre- emergent herbicide and want to seed bare spots, you must destroy the barrier on top of the soil made by the herbicide. This can be done by scratching the surface of the soil with a rake, getting below the barrier- maybe down a half an inch at most. Then add some topsoil to be safe and then seed the area.
As a rule, a preventative crabgrass control needs to be applied between forsythia bloom and dogwood bloom, or two weeks after forsythia is in full bloom. This means any lawn repair that involves starting new turf from seed must be done before the application of pre-emergent crabgrass controls. The exception is when a product containing siduron as the active ingredient is used. Siduron allows desirable grass seed to germinate and develop, while it prevents the crabgrass seed from doing so. The one product containing siduron is Tupersan, and it is available at many garden supply stores.
Remember, the best control of most weeds is maintaining a healthy lawn. Watch the height of cut, as the optimum highest cut of a desirable grass will often keep crabgrass from getting enough sun to germinate. A dense, higher cut lawn is better than any herbicide. And do not apply fertilizer in July or early August as this favors crabgrass and not your cool season lawn grass.
Any questions should be directed to Pamm Cooper : e- mail address: pamela.cooper@uconn.edu.
For details or questions, contact Pamm Cooper at : pamela.cooper@uconn.edu.
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