GB 153 Controlling Oxalis Weeds. The Ginkgo.
26:14
SUMMARY KEYWORDS
ginkgo, plant, seed, wood sorrel, clover, tree, weed, pull, pots, lawn, leaves, garden, grow, fred, bulbs, roots, smart, kgo, buttercup, people
SPEAKERS
Debbie Flower, Warren Roberts, Farmer Fred
Farmer Fred 00:00
Garden Basics with Farmer Fred is brought to you by Smart Pots, the original lightweight, long lasting fabric plant container. it's made in the USA. Visit SmartPots.com slash Fred for more information and a special discount, that's SmartPots.com/Fred. Welcome to the Garden Basics with Farmer Fred podcast. If you're just a beginning gardener or you want good gardening information, you've come to the right spot.
Farmer Fred 00:33
Just as all gardening is local, all weeds are local as well. And we're hearing from many of you about your yard's nightmare weeds, especially ones that could be mistaken for clover. But you like it; so, you let it go until it starts taking over. That's oxalis, and it's close relatives, creeping wood sorrel and Bermuda Buttercup. And another weed that crashes the Oxalis family parties, bur clover. Debbie Flower and I feel your pain on this one. UC Davis Arboretum and Public Garden Superintendent Emeritus Warren Roberts tells us about one of the best trees for its brilliant yellow leaves this time of year, the ginkgo. It's our Plant of the Week. We're podcasting from Barking Dog Studios here in the beautiful abutilon jungle of Suburban Purgatory. It's episode 153 of the Garden Basics with Farmer Fred podcast, brought to you today by Smart Pots and Dave Wilson Nursery. And we'll do it all in under 30 minutes. Let's go.
Farmer Fred 01:32
A few weeks ago, we were talking about nutgrass or nutsedge. And what a hated weed that is for many of us. Well, many of you chimed in on the Get Growing with Farmer Fred Facebook page to say, "Nutgrass, heck! You haven't seen my patch of whatever (fill in the blank)." And a lot of votes came in for whatever, including things like star thistle and bindweed and Johnson grass and kudzu and Ivy. And a lot of people don't like oxalis. And there's even desirable oxalis, but this particular oxalis you don't want. It can take a lot of punishment and come back for more. Debbie Flower is here. She has pulled her share of oxalis from many places. And actually maybe pull is not the right word. Maybe it's dig out.
Debbie Flower 02:26
No, I pull. Mostly. One major thing to keep in mind when you're trying to control weeds is this: BISS. Before it sets seed. All you're gonna do is pull and I like pulling weeds. It's therapeutic. I can remember sitting in my front yard in Portland, Oregon, pulling wodd sorrel out of my lawn, just to calm myself down after some event. So if you want to get it out, if you do nothing else, get the weed out before it sets seed, especially with this wood sorrel. Wood sorrel creates this tall capsule of seeds and when it opens it throws its many, many, many seeds. long distances.
Farmer Fred 03:10
Oh, like hairy bittercress?
Debbie Flower 03:12
Yes. Yes. Yes. Yes. Like hairy bittercress. You're absolutely right. So pulling it and those seeds can go 10 feet away. And so then you've got another infestation. Pulling it is helpful. If you leave any part of the taproot or any part of the root or any part of the stem. You have not killed the plant, but at least you have removed the above ground portions that you got your hands on before they set seed.
Farmer Fred 03:35
There are several common names for the weedy oxalises: creeping wood sorrel and Bermuda Buttercup are two of the more common names. It can be found in lawns, flowerbeds, gardens, nurseries, greenhouses, and basically throughout the world,
Debbie Flower 03:50
Right. Cracks in the driveway, cracks in the sidewalk. The place between the asphalt and the concrete on the street, wherever it can get its little tiny seed, it will grow. And of course in those tight spaces, it's harder to remove. It is perennial, the oxalises are perennial. I have ornamental oxalis in my yard. It's one of my husband's favorite plants, but it does not produce these seed pods. So it's just one clump that gets bigger and bigger and bigger and it's only there in the spring actually a little bit of it is up still flowering into the fall. It is not invasive. This wood sorrel and the Bermuda Buttercup, which are two different species of oxalis, are the weedy oxalises.
Farmer Fred 04:29
Did you know that the Greek word for "sour" is oxalis? It refers to the the acidic nature of what you would find inside it, and they warn people who have livestock to remove any of oxalis because they can suffer from oxalate poisoning.
Debbie Flower 04:47
Oh that's a swelling of the mucous membranes and so they could suffocate.
Farmer Fred 04:52
So one good reason that if you do have oxalis and you have livestock, you do want to remove that from the area.
Debbie Flower 05:00
It can be a little bit difficult to identify what is oxalis and what isn't. It looks like clover. It looks like clover, right? True Clover has a round headed flower, but the oxalis and another plant called Medicago, in the genus Medicago, also looks like a clover. So just looking at the leaves isn't gonna be super helpful.
Farmer Fred 05:24
Right? The leaves are comprised of three small leaves. it looks like three leaf clover with a yellow flower.
Debbie Flower 05:28
Right. That's the clue. Any of the three that we're talking about the Medicago, the Bermuda Buttercup and the wood sorrel all have yellow flowers and clover does not.
Farmer Fred 05:38
Yeah, the Medicago is Bur Clover, that's is the common name for that one. And that too can be found in many parts of the world. What's interesting is it's useful as a pasture plant.
Debbie Flower 05:54
The Medicago fixes nitrogen, it's in legume family. And legumes are things that fix nitrogen in their roots. I used it in teaching, I could find it all over campus. So I would pull some up and take it in into the classroom to show the nodules on the roots that are formed in in nitrogen fixation.
Farmer Fred 06:11
It can sometimes though, the Bur Clover, can sometimes be toxic to livestock, as we pointed out, and the seed pods can be a serious contaminant of wool.
Debbie Flower 06:20
Yes, the seed pods on the Medicago have little sharp points on them. And so they can attach to other things like the wool of a sheep. That's how it spreads. Yes, it's a dispersal technique. Medicago doesn't throw its seeds. The seed pods are carried away on your pants, your shoes, your sheep, your dog, your cat. The Medicago is an annual of the three we're talking about. This one is an annual, the other two are perennials and the ornamental oxalises are also also perennials. So perennials are persistent, they have some way of living over during negative times whether it's cold or dryness, or whatever it is. And in the case of the oxalis, which is the Bermuda Buttercup and the creeping wood sorrel, they have little bulbs underground,
Farmer Fred 07:09
And the University of California, on their great weed site, point out the obvious: that hand weeding is used extensively to reduce infestations and get it before it sets flower. Yes, yes, very important to do that, and they recommend the hoe, the hand pull, all those things that can help it, especially when you get it when it's young.
Debbie Flower 07:32
Yes, and even if those bulbs have formed every time you remove the top, you're forcing the bulbs, the plant, to use the food in the bulbs to create a new plant and so that diminishes the bulb a little bit. And then you see new growth on top; remove it again. If you do that, over and over and over again, you eventually rob the bulbs of the food in them and you kill the plant. But you have to be persistent
Farmer Fred 07:54
And here's why you don't want to mow it, for two reasons: Number one, the creeping wood sorrel survives and sets seed even when mowed as close as one quarter inch. Chances are, your mower doesn't get down to a quarter inch. And after using a lawn mower, creeping Woods sorrel grows, you're gonna have seeds all underneath the lawn mower. Around the blade and mower housing. So you need to clean the lawn mower thoroughly. Those bulbs are difficult to remove.
Debbie Flower 08:21
Yes, sanitation is critical. These Oxalis plants can grow from certain portions of the stem, they can grow from seed so you want to make sure that you get any equipment you use in your landscape is washed. Typically you should wash it after you use it, before you put it away. So you're not transmitting it yourself from place to place.
Farmer Fred 08:42
And this nasty stuff grows in lawns too.
Debbie Flower 08:44
It does, yes. And it can be especially if you have a stoloniferous lawn like Bermuda or Kentucky Blue Grass. It can get sort of trapped under those stolons which are surface stems and it can be difficult to pull out. The wood sorrel grows on a stolon itself and roots from place to place. So pulling it out can be sort of like a doing a puzzle.
Farmer Fred 09:04
If you're going to use a herbicide on it, and if it's in a lawn situation, know the type of lawn you have. Because it's different chemicals for different lawns. Cool season turf grasses such as bentgrass, Kentucky Blue Grass, fescues, rye grass have their own table of chemicals that can help control creeping woodsorrel. And then the warm season turf grasses like Bermuda grass, buffalo grass, Kikuyu grass, St. Augustine and Zoysia, they also have a list of chemicals that can control the creeping woodsorrel.
Debbie Flower 09:36
And they're all different. Yeah, there's no overlap.
Farmer Fred 09:39
Yeah, and it sounds like herbicides for Bermuda Buttercup is very limited, since two of the four listed are nonselective Gluphosphonate and glyphosate.
Debbie Flower 09:55
So they would kill the your lawn or whatever else is is growing in there.
Farmer Fred 09:59
Basically, read and follow all label directions, always. And I guess one, I won't say a safe way, but at least a fairly safe way is if you have the case of the Oxalis growing in the lawn situation, maybe apply a pre emergent that's approved for use on turf. Yes, that might help. And they have very hard to say names, so I won't, but we will list them in the Garden Basics newsletter as far as pre emergent herbicides for cool and warm season, turf.
Debbie Flower 10:26
And if you don't have that list with you, and you're in the garden center and looking for chemical,
Farmer Fred 10:33
Read labels, always read labels.
Debbie Flower 10:35
Labels must show the weed you're trying to control in the situation you're trying to control it in. So oxalis or woodsorrel and lawn. Or oxalis or wood sorrel and ornamental landscapes, something like that.
Farmer Fred 10:50
And I would think that when it comes to lawn, they'll break it down into cool season or warm season.
Debbie Flower 10:55
You need to know what kind of grass you have, as Fred said.
Farmer Fred 10:57
Yeah, all right. It's a tough one. It is oxalis. Common names include creeping wood sorrel, Bermuda Buttercup, and then a different genus, Medicago. And that would be the bur clover.
Debbie Flower 11:09
Yes. And that's an annual, that one. I don't think you would even want to approach using an herbicide. Potentially a pre emergent, but nothing for once you see the plant. Just pull it, get it out of there.
Farmer Fred 11:21
I remember back, and I got paid to do this; I was eight years old, and a lady down the street wanted me to come weed her front yard, which was all rocks. And it was Bur clover. And I just remember how bloody my knees were.
Debbie Flower 11:35
Oh, your knees, your fingertips. I was weeding last week in my son's property, which has sections of rocks and my fingertips are a little damaged because of it.
Farmer Fred 11:45
Yeah, bur clover seems to like rocks to grow on.
Debbie Flower 11:49
And those seeds can sift right down through those rocks and get in the little crevices and germinate.
Farmer Fred 11:54
Yep, no doubt about it. Oxalis can be a bad weed, or a pretty plant. Choose carefully, pick your poison. Alright, Debbie, thank you so much.
Debbie Flower 12:04
My pleasure, Fred.
Farmer Fred 12:09
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Farmer Fred 13:13
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Farmer Fred 14:04
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Farmer Fred 15:35
Every week we like to talk with Warren Roberts out of the UC Davis Arboretum and Public Garden. He's their Superintendent Emeritus, a very knowledgeable plant person. And today the Plant of the Week: It's just a gorgeous tree. It's one of my favorite trees. It has one heck of a show of fall color. And it's a very interesting tree. It's the ginkgo. And Warren the ginkgo is just an amazing tree with a long history.
Warren Roberts 16:09
Yes. In fact, it goes back to the fossils. The modern ginkgo goes back 200 million years.
Farmer Fred 16:18
That's a long time, right? Is it technically a conifer?
Warren Roberts 16:22
Well, it's not a conifer because it doesn't really have cones. But it is a gymnosperm, which is the larger category, which includes conifers, and a number of other interesting plants. It looks like a regular flowering tree but it is not.
Farmer Fred 16:40
But the leaf is certainly unusual.
Warren Roberts 16:44
It's usually triangular. The tree is sometimes called maidenhair tree because the leaves look something like maidenhair ferns, but with larger leaves. In California, we just call it ginkgo, GIN-KGO. That's my mnemonic device to remember how to spell it. The first part, Gin, is something you might imbibe in. And KGO is a radio station in San Francisco. So Gin-KGO, the maidenhair tree
Farmer Fred 17:14
Yeah, there are some announcers at KGO that could drive you to drink, like gin.
Warren Roberts 17:18
Yeah, the ginkgo can become a very large tree. There was one in Kamakura, Japan, I think, was the biggest on record that recently fell. I would have thought that they would have propped it up better, but down it came, and that particular Ginkgo has a very unusual characteristic in that stalactite-like growths would come down from the branches. And some of these were several feet through, and some yards long. I've only seen one of those outside of Kamakura. There was one in Sacramento that had this characteristic. And that particular one is a female cultivar. I love the ginkgo, it's beautiful. I rarely recommend that people plant it, because the grafts often fail. Now the the fruit of the ginkgo is the seed. It's actually the embryo inside the seed. It is edible. But the flesh covering the outside of the seed is, when it is ripe, it smells about as bad as any smell you can smell. It smells a bit like vomit.
Farmer Fred 18:32
I was gonna say it smells like the aftermath of a fraternity party.
Warren Roberts 18:35
Or the aftermath of a dog. Yeah, it's really unpleasant. So select forms, and they're about I guess 60 different ones available, are males. So the male does not produce fruit. It produces a a kind of tactile-like flower, that when it appears, is the pollen. The fertilization of the seed is interesting in itself and it also involves motile sperm. So who knew?
Farmer Fred 19:03
Who knew right? Now, to give the fruit it's due, there are cultures that do prize that fruit.
Warren Roberts 19:10
Yes, there are. We have a big old ginkgo from the 1870s in Capitol Park in Sacramento. And I guess the trunk is, oh, I don't know, six feet across. It's not as big or old as some of the ones back east in Pennsylvania, and so on, but it's big. Now, it's never a problem, even though it's a female tree because people from that culture or that have ancestors from China or Japan or Korea or Manchuria or descendants, at least to this second generation, will go out with plastic bags on their hands and pick up the fruit and actually clean the flesh off. Clean it really really, really well. Dry it and then those seeds can be cracked. They look kind of like a large pistachio. And then inside is a kind of a starchy, slightly rubbery embryo which is used in festival soups, celebrating winter, that it's evolved, you have to be attuned to that I, for example, I've never felt the need. But thank goodness that these people do this and it's providing a service. And it's a win-win situation, they get the seeds which they can use for their cooking, and it cleans up the mess.
Farmer Fred 20:29
If I recall correctly, there have been warnings about don't eat too many of them, like limit yourself to three or four if you're going to imbibe in those, just because if you're not used to it, it could cause some internal digestive issues.
Warren Roberts 20:44
Oh, dear. Well, there's never a perfectly good thing, I guess. No, no, I've heard that too. And in fact the most I've ever eaten in one sitting would be I think three or four, in a wonderful Chinese recipe, soups that includes daylily buds as well. Yeah, very tasty. So the ginkgo. There's been some discussion about the powder from the ginkgo leaves. These can be used to help the mental acuity, but I don't know if that has proven out in science. I've just mentioned it because because it is happening. So if the graft fails, when the male clone is grafted on the tree, you really can't tell it right away because the sprouts that come up from the root stock look pretty much like the scion. But the sad thing would be, in about 11 years or 15 years, if it happens, there's a 50-50 chance that the seedling is a male or female that you get a female tree then you have to deal with the considerable aftermath.
Farmer Fred 21:51
Well, it depends. Some people do make lemonade out of lemons, you know,
Warren Roberts 21:57
That's true, but you have to be the person that makes the lemonade Yes. But I recommend sometimes if you want to, if you got to have a ginkgo, plant a small grove of them when the the gender manifests itself, those ones can be removed and you'd still have at least one male ginkgo with its beautiful foliage and the fall color foliage particularly.
Farmer Fred 22:19
The beautiful yellow fall foliage is just so outstanding on the ginkgo. I would be hard pressed to cut it down.
Warren Roberts 22:27
I would be, too. But if you had a grove, maybe you do some thinning, the leaves are just as beautiful on the ground as they are tree and locally in the Sacramento. I think there's somebody who makes drawings but with a rake. And we've done that in the Arboretum at UC Davis campus as well.
Farmer Fred 22:48
And the beauty of that is the fact that the tree tends to drop most of its leaves at one time so you can get as artsy as you like.
Warren Roberts 22:56
That's true. But one of the interesting things about ginkgo, and there's so many, is it seems to have outlived its pests. Ginkgo has almost no known bothersome pests or insects, at the least that I know of. So that's good.
Farmer Fred 23:13
Can I tell you a story? Sure. I had a ginkgo growing in my front yard. And one day, I noticed it's kind of leaning. I didn't know what's wrong. So I went out to take a look at it, and I just gave it a gentle little push. And it fell right over. Oh, and I was looking at the root area. The roots were gone. They had been munched on by gophers.
Warren Roberts 23:35
Oh, my goodness. Thing about those creatures. That's the Western pocket Gopher, I guess, Correct?
Farmer Fred 23:46
Yeah. Well, that's okay. I planted another one. Yeah, in general ginkgos, though, aren't bothered by insects or diseases. They're very tolerant of a wide range of conditions. As far as the acidity of the soil or alkalinity of the soil. They're not bothered by air pollution or heat. They're just a great tree.
Warren Roberts 24:09
They do need some water during the dry season, though to be successful. They will survive long stretches without water. But if you want the tree to be healthy and grow faster, and it's pretty slow growth, you need to water them at least every two weeks, a good soaking.
Farmer Fred 24:29
That's right. But they're they're easy to take care of.
Warren Roberts 24:32
They are easy to take care of. And since you have so many different varieties, you can get a variety with somewhat upright branches, some of weaving branches, horizontal and so on.
Farmer Fred 24:43
Exactly. It's the Ginkgo, G I N - K G O. I guess that would be the ginkgo biloba we're talking about.
Warren Roberts 24:51
Yes, just one species that has survived. And it's got its own family too. It has its own family, its own order and all kinds of things.
Farmer Fred 25:00
So, it is a deciduous tree and it's definitely a showstopper in the fall with the bright yellow leaves. The Ginkgo, another great Plant of the Week from Warren Roberts, Superintendent Emeritus of the UC Davis Arboretum and Public Garden. For more information, visit their website: arboretum.uc davis.edu. Warren, thanks again for the ginkgo.
Warren Roberts 25:23
You're welcome.
Farmer Fred 25:35
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