pre emergent and reseed

Discussion in 'Pesticide & Herbicide Application' started by bobby perez, May 12, 2002.

  1. bobby perez

    bobby perez LawnSite Member
    Messages: 86

    Why put down a pre emergent on the lawn for weeds.Wouldn't that interfere with the natural process of the grass reseeding itself in the Spring when we cut and discharge or mulch. Or do we then charge them for reseeding in the Fall. Some one asked me this question
  2. tremor

    tremor LawnSite Bronze Member
    Messages: 1,476


    Desirable perennial grasses don't "reseed" themselves in the spring. Seedheads do try to form around now on poorer varieties of Bluegrass. The better cultivars generally don't make seeds under normal mowing heights. If these seeds were allowed to stand without mowing all summer long, they'd be ready to harvest by (around) August. At which time a preemergent application would be gone.

    Poa anua makes seeds that don't need to mature on the plant. That's unfortunate since it is considered by most to be a weed in it's own right. Preemergents can hold down some Poa. So the argument is still favor of the herbicide.

    Commercial seed producers of good integrity also have weed control programs. If not, the fields would be overrun by weeds & the grower would lose the marketability of his harvest & probably any contractual claim to the cultivars patented name.

    The seeds that germinate & establish most consistantly in the spring (here in the cool humid northeast) are summer anual weeds like crabgrass.
    In nature, perennial grasses are more capable of seed sprout & establishment in the fall. So your argument against preemergent herbicides is therefore running against the grain of nature if a lawn of desirable perennial grasses is the goal.

    Try collecting the clippings on some of the lawns you cut. Seperate the seed you find. Plant them in clean soil. Post the resulting grasses. The only grasses you can collect that will germinate now is the Poa anua.

    Most of my own front yard is a wicked shade problem. So, Poa is the main reason I bag here at the house, but it's still a losing proposition without the occasional squirt of Roundup, regular preemergent apps, & sometimes just a trowel.

    You may have customers who complain about "the little white flower" weeds. You look & find all grasses. That's Poa.

  3. bobby perez

    bobby perez LawnSite Member
    Messages: 86

    Thank you Steve for your informational reply . Iwill share that with the customer,and put their mind at ease. Iknew there was a good reason why we do things the way we do,I just didn't have the right answer for them. Again thankyou for your knowledge,and timely responce.

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