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How to Apply Roundup Pesticide with a Sponge Applicator | DIY No Overspray

Hawk Hill’s fences are draped with heavily scented honeysuckle vines, humming-bird enticing trumpet vines, and deep emerald-toned Virginia Creeper. Unfortunately, these vines which so perfectly provide a thick cover of privacy at each of the property lines also peep up invasively at all points not mowed regularly, including my flower beds.

I’ve spent years weeding flower beds religiously, and other years simply giving in by mid-June and surrendering to the never-ending tide of vines re-claiming my flower beds. This year, I got smart and decided to outsmart the vines by not merely weeding, but by trimming and precise application of strong herbicides.

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I brainstormed methods to apply herbicide precisely with one hand (so the other could hold and use a pair of hand pruners) and came up with the idea illustrated below. I’ve made my own sponge tip applicator, but you can buy a sponge-tip applicator bottle which should work as well or better than the DIY bottle below.

How to apply roundup directly to target plants without risking overspray or runoff

Applying a strong herbicide to the cut where a weed was trimmed ensures that the pesticide penetrates the plant’s system so the weed will not grow back. This is particularly helpful in killing off vines with underground runners and perennial weeds.  This method ensures my weeding has long term, not just short term benefits, and the precise application of herbicide means I can use as little chemicals as possible to get the job done.

Step 1:

Find a small bottle with soft (squeezable) sides and fill with your herbicide of choice. The best bottle, I’ve found, is a rinsed out craft-paint bottle

I use Triclopyr (usually marketed as stump/brush killer) for its ability to kill off very resilient vines like honeysuckle and trumpet vine.


Step 2.

Cut a piece of porous sponge that is about 3-5 times as large as the opening/neck of your bottle.


Twist sponge to compress


And while smashed, insert into the neck of the bottle:


Now you can very precisely follow each cut with your hand pruners with a daub of herbicide, ensuring you won’t have to do the same weeding on the same plant over and over:

Elm trees like this one are notorious for sending up multiple new trunks each time they are pruned back (you can see the trunk cut back last year, in this photo). Dabbing stump/brush killer on the freshly cut trunk means the herbicide will penetrate the plant’s system and I won’t have to cut this treat back again and again in coming years.


Saturday 12th of August 2023

Will this not kill the whole shrub/tree?

Lindsayanne Brenner

Thursday 17th of August 2023

We have used it for quite a while and it doesn't seem to have any negative impact on the overall plant. Granted this is a small sample size, but please let me know if you experience any negative results. Thanks for your comment!


Tuesday 25th of July 2023

Great idea! Will be trying this on quack grass in my lawn. Little tedious but trying to spare the good grass.

Lindsayanne Brenner

Wednesday 26th of July 2023

Agree - tedious, but hopefully the results prove to be worth the effort! If possible, let me know how it goes and if I should make any updates to the article based on your experience!


Wednesday 17th of May 2023

Brilliant! I was thinking of using a paint brush to apply Round-Up to my crabgrass, but your method looks superior.

Lindsayanne Brenner

Wednesday 31st of May 2023

Glad you found this helpful! I love figuring out and sharing interesting solutions, so I'm glad that by ended up helping you!