My pansy gardens keep becoming infested with the same unwanted plants over and over again: a long stem grass of some sort that grows very sparsely, clover, joe pye weed, ferns, tiny things that look like oak leaves (could be poison oak, so I don’t touch them with my bare hands), some sort of reddish ground cover plant that has wiry and slightly spiky tendrils and a few things I don’t even have language to describe. No matter how many times I pull them out, they’re back a week or so later.
I have lots of weed killer, but I don’t spray it in the garden directly because I don’t want to accidentally kill either the pansies or the seedlings I just planted. But would using a small paint brush to paint weed killer onto the weeds, and only onto them, work?
By “work” I’m more concerned about how it might affect the wanted plants (could it wash off and spread? It’s supposed to kill weeds if it stays on at least 20 minutes to dry before it rains, but… If it “gets down to the roots” like ads often claim, can it seep into the soil nearby too?) than I am it being an over effective thing to do: if it helps even a little, it’d be worth the effort.
What you’re thinking of doing is called “wiping” and farmers do it for the same reason you want to.
What kind of herbicide are you using? If it’s glyphosate (Roundup, etc.) then it doesn’t seep from one plant to another.
Make sure you apply it only to the leaves of the plant, not stems, and that the leaves are both dry and clean (not dusty.) Be careful about having droplets of herbicide flick off the brush.
Remember, plants “shut down” when it gets hot, and it’s exceptionally hot where I live. Follow the directions on the label regarding weather.
Spreading/creeping plants like ivy and kudzu are notoriously hard to kill, and will probably require multiple treatments until the frost.
painting is a good method for glyphosate solution.
a good applicator is a sponge. you might find applicators in a garden store. you could also easily use a dish washing sponge on a hollow wand which is made to contain detergent solution, look for that in kitchen supplies. tip the sponge end up so you don’t drip on other plants. paint it on the leaves, in 3 to 7 days you will see the weed start to die. you may need to retreat vines.
Numerous weed killers become ineffective when they touch the soil. If you can manage to get it on the foliage of the plant you want to kill, you are likely safe and need not worry about runoff.
The leaves are designed to soak up moisture (i.e., the herbicide). The stems are designed to hold the leaves up, but not soak anything up. It’s basically a wasted effort, plus, trying to get the stuff on the stem makes it more likely you’ll inadvertantly brush the plant next to it.
I have done that with seedling trees in my ground cover. There are materials that kill grass and leave flowers. Ortho makes one. I have only seen it in ready to spray quarts. I have been using Bodine’s Grass Beater. It comes as a concentrate, over $20 for a half pint bottle, but very effective on grass in flower beds. It kills wild onion too.
You can also take a piece of cardboard and cut a slot in it. Slide the cardboard under the leaves, and let the stem pass through the slot, then just use the sprayer up close. That’s how I do the poison ivy near other plants. I’ve seen something similar done with a small hole in a piece of cardboard. Hold the hole over the leaves and spray. A few stray drops will leave some brown spots on innocent plants, but probably not kill them. But you have to be careful, it doesn’t take much.
Will this work with invasive morning glory vines. There are literally thousands of vines in the rear half of my back yard, embedded among dense shrubbery and flower beds. There’s no way to root them out, since I’d be causing damage trying to get to their origin. If I painted Round Up on some of the leaves, would it travel down the vine to the roots and kill it, without jeopardizing my other plants?
with vines you could cut back leaving a dozen leaves on the lowest stem, treat those and the fresh cut on the stem. since there is a lot of root tissue it may take a few treatments, treat new leaves as they appear plus make a fresh cut on the stem and treat that.
A few years back I made my own weed wiper by rubber banding a cotton ankle sock over the end of my pressure sprayer. Spray to load and wipe away! It takes a little bit to work out how much to spray before it drips, but the collateral damage is still minimal.
Plants don’t shut down when shut gets hot. If they did they tropics would all be desert, since it is hot 8 months a year and the winter is usually bone dry. For that matter summer cropping would be impossible anywhere in the world.
Plants shut down when they are stressed. For a minority of species of plant that occurs when they get too hot, but far more plant shut down when they are too cold.
People often erroneously believe that plants shut down due to heat because they are not watering enough, and the plant is suffering from water stress. If a plant has enough water then heat is unlikely to have any effect at all.
Neither leaves nor stems of plants are “designed” to soak up anything. Application of herbicide to the stem is known as basal or basal bark application, and for the vast majority of herbaceous or light woody plants the stems are a better site of herbicide application than the leaves because it provides direct access to the phloem feeding the roots, and the roots are what the herbicide is ultimately targeting.
The reason that stem application it is not more widely for small weeds is that it is more difficult to target just the stems than to target the whole plant generally.
It will greatly increase the effectiveness of the herbicide is you can target the stems. Far from being a wasted effort, it should be the preferred method of application if it can be achieved.
Comments about stem application increasing the chance of damage to non-target plants are also highly dubious. While it certainly could be true in some highly unusual situations, in the vast majority of cases exactly the opposite is true. Basal application is preferred to foliar treatment where a risk to non-target plants exists. Foliar treatment targets a broad area, and thus has a high chance of affecting non-target plants. In contrast stem applications target an area order of magnitude smaller. Think for a second about how much stem area a plant has compared to its leaf area and it will be quite clear why stem application almost always reduces the chance of affecting non-target plants.
A good technique (or so I’ve heard) for twining weeds is to offer them something to climb up - ideally something smooth such as a piece of dowel, a broom handle or a plastic rod, stuck vertically into the ground, then when the weed growth reaches the top of the stick, push it down into bunch at the bottom, pulling out the stick.
Place a funnel (made from the top four inches or so of a plastic bottle) funnel over the gathered bunch of plant growth and squirt herbicide in through the cap hole.
Just repeatedly pulling them out can work too - even for really persistent and troublesome species.
I got rid of all the horsetails in my previous garden by just pulling off all the top growth every time I saw some. With very few exceptions, without green parts above ground, plants cannot manufacture food and will exhaust their reserves, then die.
The reason this worked well in the case of my horsetails was a combination of factors, but chiefly, they were growing in a patch of ground which did not have any uncontrolled/able borders (so they couldn’t recolonise the plot from a neigbouring area) and I was able to check and pick every day (so they never got a chance to recover from the onslaught).
This isn’t entirely correct. Uptake of glyphosate (roundup-type) herbicides is through the stomata (microscopic pores in leaves and stems), and these do indeed close under conditions of high heat/aridity in order to prevent excessive moisture loss. The temperature at which this occurs varies with the type of plant, but most temperate-region plants do in fact “shut down” during the hottest part of the day. If sufficient moisture is available, transpiration will continue at somewhat higher temps, but it is generally acknowledged that herbicide uptake is negatively effected by applying in the heat of the day. Furthermore, while some plants do have stomata in the stems, the majority of uptake occurs in the leaves. I don’t know of any literature that advises stems over leaves as an application site. Some have claimed that application should be to the underside of the leaves, as the stomata open further there than on the top, but I’ve personally never been able to tell any difference.
It should also be noted that little or no uptake occurs through the woody stems. Indeed, roundup can be applied with relative impunity around the trunks of trees, shrubs and vines - as long as it doesn’t get on any “green” parts it will kill herbacious weeds around the trunk but will not affect the tree or vine.
Some information on effect of heat on transpiration here:
Hand pulling can work. I tried a number of things but never got rid of the severe crab grass infestation in my yard until I hand pulled. I refrained from MSMA to spare my red fescue. However, I now am fighting nimblewill. I even put Round Up on a section of lawn with it and cinifoil. It reduced the cinifoil, but the nimblewill came back as strong as ever.
I am now sacrificing the red fescue to fight the nimblewill with MSMA. Repeated, strong doses seem to kill it. It is regulated and hard to find. I think I came by enough of it last fall to wipe the stuff out this year.
Yeah, you can kill all the weeds there at any one time, but more seeds will blow in and sprout continually. I think what you really want is a good mulch, which will drastically cut down on the amount of weeds sprouting.