impervious weed

bill999(z6 Pa)May 11, 2014

After much web searching and several false hits this ubiquitous weed that plagues my lawn outside Pittsburgh has been identified as thyme leaf speedwell. It does not react to weed and feed nor does Spectracide weed killer affect it despite it being listed on the label. Look closely at the white flower with purple streaks and the spade shaped hairless leaves: https://www.scottslawnservice.com/sls/templates/index.jsp?pageUrl=slsthymeleafspeedwell

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andy10917(NY 6a)

To get good answers from experienced people here, it's better to post the active ingredients in the weed killers you've applied, rather than brand names.

    Bookmark   May 11, 2014 at 11:43AM
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bill999(z6 Pa)

I really don't have much hope that this can be eradicated from my lawn. Multiple web sites have noted the resistance thyme leaf speedwell has to weed killer. One site actually said Quinclorac would kill it but the Spectracide label shows that chemical at .235% and that product isn't working for me. The rest is 2,4-D, Dimethylamine Salt and Dicamba. Their label also specifically lists this and other speedwells as weeds it controls. Having treated some patches twice I know that's not true. I'll probably pull it by hand for the exercise.

    Bookmark   May 11, 2014 at 6:11PM
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botanicalbill(9b SWFlorida)

Did you spray when the weeds were growing?

Did you wait a few weeks after spraying to see if the weed had stopped growing?

The best practice to use herbicides is when weeds are growing at their best, hot and not dry weather. This is because the vascualr flow of fluid in the plant is at its highest and the herbicide will be moved through the plant.

If you sprayed after a few warm days and then a cold snap hit, you probably wasted your spray.

    Bookmark   May 12, 2014 at 1:22AM
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