South Florida zone 10b.
I have planted some Costus (Ginger family) in a 50' long planter area. However the weeds are growing like wild fire and I am unable to keep up with pulling them. I wanted to use some weed killer to control the weeds (clover leaf type, see a pic here
Is this true? Is there a better way to control the weeds beside hand pulling?
Thanks,
MC
Take a piece of the weed -- not merely one leaf -- to a "real" nursery (not a lumber yard or hardware store) for identification. This might be oxalis instead of clover.
There is a specific weed control that severely burns oxalis, sufficiently to kill most of it, without harming other plants (except for spotted spurge, another weed). Sold under various brand names, it contains ammonium thiocyanate, which quickly decomposes into a urea form of fertilizer; sodium thiocyanate is about as effective. Any oxalis plants that survive must be hand dug, for which I recommend the use of a paring knife. Be alert! Oxalis readily forms seeds, which are not affected by the chemical; the thiocyanates act only on growing foliage.
If your weed is indeed clover, hand pulling is the best control. Do this before it flowers, and you won't have to repeat. Try to leave some of the roots in the soil; they are an excellent source of nitrates for nurishing other plants.
Sorry David, but it looks like bullshit to me, thiocyanate is sulfur + cyanide. Pull the god damn weeds. Don't be a lazy ****. You don't want to eat heavy metals. Oxalis isn't that invasive, and kids love to chew it, even if it does bind up calcium.
In message , Billy writes
The photo looks like oxalis.
I don't find Ammonium thiocyanate as a narrow-spectrum weedkiller particularly plausible, but there are no heavy metals involved.
Google's not being particularly informative today, but it looks as if ammonium thiocyanate is usually used combined with aminotriazole (amitrole) - and acts by slowing the action of the aminotriazole allowing it to reach the roots and kill the whole plant, rather than just the leaves.
This combination is marketed as an oxalis killer
Aminotriazole, fide Wikipedia, is a carcinogen.
There are products marketed for the control of broad-leaved weeds in pastures and cereal groups. But while Costus is a monocot, sensitivity to weed killers doesn't line up nicely with phylogenetic clades (e.g., fide Wikipedia, bromoxynil is used with flax and mint, as well as with monocot crops), so it cannot be assumed that Costus is not sensitive. Broad-leaved weed killers tend to be nastier chemicals.
What heavy metals?
In any event, I would simply pull the weeds. Do it in spring and you'll be done with them. I'd rather spend a few hours pulling weeds than many more hours researching, shopping for, and applying herbicides.
Una
Sorry about that. I probably shouldn't post late at night. Arsnic isn't a heavy metal. It is just very, very, nasty stuff.
Una wrote:
What arsenic?
Una
Billy
Cyanide is carbon and nitrogen bonded (CN) not heavy metals. Whether thiocyanates on your land are a good idea is another matter that I am staying out of.
David
The last time I looked at a bottle of Oxalis-X, the only active ingredient was ammonium thiocyanate. No amitrole, no other herbicide.
Ammonium thiocyanate will burn other plants; but in most cases it will not burn sufficiently to kill the plant. However, the label did warn against spraying it on or near junipers. It is effective against growing oxalis and spotted spurge and leaves no residue other than urea (a fertilizer) and sulfur (good in my alkaline soil).
I haven't bought Oxalis-X in a long time. Fortunately, oxalis is now a rare weed in my garden. When I find it, my paring knife digs it out (with help from my right hand).
Unfortunately, spotted spurge is too common in my garden. But it tends to grow my decomposed granite walkways where I can use Roundup.
One precaution in keeping oxalis out of your garden is to inspect carefully all containers of new plants at the nursery. Oxalis is often found growing in the containers that also contain the shrub or perennial you really want to buy. Buy only the desired plant, and reject any that come with oxalis.
Excellent point. I assure you that arsenic is, occasionally, the right answer to some questions. I'm afraid that I had been thinking about pesticides at the turn off the 20th century, here in the US of A, and lead arsenate was a prominent culprit. Late at night (for me), and I jumped the track. It's 6:30 PM where I am. Disregard all further posts until tomorrow. Now where did I put my happy hour?
Oh, jump on in. Apparently, I a way off track on this particular discussion. It happens. Find the truth. Go get 'em.
Flowerbeds should either be small (to reduce hand weeding) and/or mulched to control weeds.
i'm confused. I googled oxalis and clicked on
There are ornamental oxalis that are intentionally planted in gardens. My Sunset's "Western Garden Book" lists O. acetostella (wood sorrel or shamrock), O. adenophylla, O. hirta, O. lasiandra, O. oregana (redwood sorrel or Oregon oxalis), O. pes-caprae or O. cernua (Bermuda buttercup), O. purpurea or O. variabilis, and O. versicolor (candy cane sorrel).
Then there is O. corniculata (yellow oxalis). This is a weed and not at all ornamental.
Thanks - I've never seen that variety.
I water them, and the ferns until mid-summer, when they disappear with no help from me. I can see purplish-pink ones out my study window right now. For the time being I have the white flowers of wild onions, the oxalis, blue forget-me-nots, and pink dead nettles for color in my yard. It's not that bad.
I am confused. You all suggested to pull the weeds. I have spent 3-4 hours on my knees pulling the weeds. Two weeks and one rain storm later they are all back, in full force. The weeding has to be done every two to three weeks, continuously from March to November. That's what I have been doing last year.
So this year, I dug up ALL the costus, all their roots along the entire planter area. I then turned the soil over several time, pull out all the weeds and their roots. I then laid down weed barriers, except for a sliver down the middle. Planted the costus back in, then put 3" of granite over the entire area.
So far so good.
Then we had some heavy rain. Then they are ALL BACK, again, through the weed barriers, through the granite.
It is small in a sense that it is only three feet side, but 50 feet long (along the perimeter of the house). I had weed barriers down, on top of it is 3" of granite stones.
Didn't matter, they spread like wild fire. I pulled them, they come back in two weeks.
MC
I think we need to see a photo of the actual weeds in your Costus bed.
Also, do you literally "pull" the weeds?
Una
Please, give us a picture. You have been asked many times. Your plant doesn't sound like oxalis.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.