At Home Living: Holding back the crabgrass invasion

It sure seems like we have had a long winter, dont you think? I am thankful for the sunshine and the warming days! Except now is when my phone rings off the hook with lawn questions and especially about crabgrass. Let me save you a phone call and tell you all you ever wanted to know about crabgrass in one short article. Do call me if you have questions but, here is good information to get you started.

Buying crabgrass preventers is a little like buying laundry products. It used to be simple, soap, softener, and bleach. Now, there are so many combinations its mind boggling. Bleach that is color safethat makes me go - huh?

Crabgrass is a summer annual grass that germinates in the spring and dies with the frost in the fall. Hot, dry environments, like Kansas summers, encourage crabgrass because cool-season lawns are struggling at that time. Crabgrass will often take over if the lawn is not well taken care of. A healthy lawn is always the best weed preventer.

There are two chemical methods to control crabgrass: preemergence (before it appears or slightly after), and post-emergence (after it appears).

Preemergence products dont actually keep the seed from germinating, instead just after germination the new plant absorbs the chemical from the soil and dies. With few exceptions, most crabgrass preventers will have no effect on existing crabgrass plants. Crabgrass germinates when the soil reaches 55 degrees or warmer for 3-5 days at the inch level. This happens typically around May 1 so April 15 is a good date to shoot for if a spring application of product is made. Note: not all spring weather cooperates with gardeners. A good indicator for timing product application is to watch the Eastern Red Bud trees; when they begin to reach full bloom its time to apply crabgrass preventer.

Dimension and Barricade are the only two products that will give season-long control of crabgrass from a single application. In fact, they can be applied much earlier than April 15. Dimension can be applied as early as March 1 and Barricade can be applied in the fall. Both will retain their effectiveness. Because of the way these products work (killing seed as it germinates) new grass seed can not be planted during the same season.

If you need to plant grass seed in the spring (fall is the better time) here are a couple options:

Tupersan can be applied while seeding. It will allow the grass seed to germinate while preventing crabgrass and various other weeds. The draw back is that it must be reapplied in 8 weeks and is not overly effective as a weed preventer.

I prefer allowing grass seed to germinate and two weeks after it emerges from the soil applying Dimension. Dimension is one of the rule breakers because it can kill crabgrass at germination and in its very young stage (2-3 leaves). Dimension is also the best choice when treating a lawn that was planted last fall. It is kind to young tall fescue, perennial ryegrass and Kentucky bluegrass seedlings.

Note: Products that contain Dimension and Barricade may use the common name rather than the trade name. The common chemical name for Dimension is dithiopyr. A product with this in it is Turf & Ornamental Weed & Grass Stopper by Hi-Yield. The common chemical name for Barricade is prodiamine. This is found more often in a weed and feed product like Fertilomes All Seasons Lawn Food + Crabgrass Preventer. (It is best for your lawns health to apply preventers in April and fertilizers in May so using Barricade in the fall is a good idea.)

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At Home Living: Holding back the crabgrass invasion