Tony Koski, Extension Turf Specialist
Since it was first introduced in 1974, Roundup (glyphosate)
has always been sprayed on weeds. Because it is largely non-selective (will
kill or harm any plant that is sprayed) in what it controls, using Roundup and
its generic counterparts near desirable plants has to be done carefully to
avoid unintended injury. The introduction of Roundup Precision Gel Weed and
Grass Killer potentially makes it easier to apply glyphosate to individual
weeds – without the concern of overspray, wind drift, and other application
errors that could harm desirable plants. But a question we have, as with all
new technology, is: does it work?
The application process reminds one of using a gel deodorant
stick. A button on the bottom of the stick is clicked until the gel (containing
a 1% concentration of glyphosate) is extruded through holes on the top of the
stick. You then apply the gel by wiping the leaves of the weed. Sounds easy,
right? What I
found, however, was that – to get a decent application of
herbicide to a weed’s leaf surface – you have to support the leaf with your
other hand while applying the gel. Of course, a rubber glove should be worn to
avoid wiping your hand with the gel in the process. (Gloves should ALWAYS be
worn when using any pesticides, whether natural/organic or synthetic types).
Because glyphosate is a systemic herbicide, complete leaf
coverage isn’t essential to get good weed control. With the gel, you get
streaks of gel on the leaf surface – which should be sufficient to control the
weed. I tried this on some plantain growing in a groundcover bed outside of my
office. The series of photos
shows the progressive death of the plantain. While
plantain is admittedly one of the easiest landscape weeds to kill, the Roundup
Gel worked well on this weed. For those of you expecting “instant gratification”
weed control, you will have to be patient with this product. In the case of
this plantain, it took about 16 days from application to death. I will next test
this on quackgrass growing in juniper beds and perennial beds, which could be
an excellent use for this product.
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| Roundup Gel applied on 23 June |
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| Injury appears the next day thanks to the pelargonic acid that is also in the gel stick; complete leaf coverage (I did try!) would have burned the leaves down more quickly. |
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| Complete death is achieved after about 2 weeks |


















