330 Q&A Bermudagrass Control? Black Plastic for the Garden?

Show Transcript

330 TRANSCRIPT Bermudagrass, Black Plastic

Q&A Bermudagrass Control? Black Plastic in the Garden?

Farmer Fred

Welcome back to the Tuesday edition of the Garden Basics with Farmer Fred podcast. Unlike the Friday edition, we're dedicating the Tuesday podcast to answering your garden questions. Stay tuned to find out how you can get your garden question into the program. So come on, let's do this!

HOW DO YOU GET RID OF BERMUDAGRASS?

Gail in Orangevale

Hello, Farmer Fred. My name is Gail and I live in Orangevale. I would like to start a vegetable garden as well as a cutting garden flower garden in my backyard. I have a significant amount of space, but it's all been Bermudagrass. Yes, the dreaded Bermudagrass. I'm wondering what's the best way to get started. I want to start small with tomatoes and peppers in the vegetable garden, and maybe some zinnias and sunflowers in the cutting garden. Anything that you might be able to tell me for starting from scratch in clay soil in Orangevale that has been Bermudagrass for a long time would be very helpful. Thank you.

Farmer Fred

Well, thank you, Gail, for using SpeakPipe to give us that question. Debbie Flower is here, America's favorite retired college horticultural professor. Gail, how about moving? That always solves a Bermudagrass problem. The Bermudagrass is forever, as I'm fond of saying. Frankly, I would wait. I know you want to garden this year, but maybe  put it off for a year and then spend this summer doing a little soil solarization, Debbie.

Debbie Flower

Yes, I agree, except that I would say get some containers, maybe half wine barrels. Make sure you drill holes in the bottom.

Farmer Fred

Or Smart Pots.

Debbie Flower

Or Smart Pots. Excellent idea. And grow your tomatoes, peppers, and cut flowers. It sounds wonderful. I'd love to be a fly on the wall of your garden as it grows. In those containers, you'll learn about the plants, taking care of them. And then solarize the ground this summer. The Bermudagrass is horrible, as you know, to deal with, and it's never gone, but it does slow down, shall we say. I had a lot of it in my yard and solarization helps. And then when it pops up, I'm right on it. Get a hori -hori, the Japanese gardening knife. Get a big one, they come in some different sizes and that's an excellent tool for getting the Bermudagrass out. Bermudagrass has rhizomes, which are horizontally growing underground stems; and it has stolons, and stolons are stems that grow along the surface of the soil and steal space, as the plant roots in at each of the nodes. So it has both of those. And you'll think you've got it all taken care of and then it pops up somewhere else, and I have to go out with my Hori Hori and dig down to get those rhizomes out of the ground. And it's never totally gone. But doing that and using a lot of mulch, organic mulch, I'm using arborist wood chips, that helps keep the soil soft and makes it easier to dig them out. Shade also prevents Bermudagrass from spreading as vigorously, but you're going to want full sun for your crops.

Farmer Fred

Bermudagrass was the lawn de jour not that long ago. You go back to the post -World War II era and a lot of people in California, especially, had Bermudagrass lawns. It was praised far and wide for its excellent resistance to heat and drought, low water use, dense sod formation, tolerance of a wide range of soil pH ranges, good tolerance to salty water and conditions, good traffic tolerance, relative ease of establishment, and grows on hard soil surfaces and shallow soils better than most other grasses. So you can see how it could take over. It can grow anywhere. That's the perfect lawn. So it had its good points, but then it kind of gets out of control because of rhizomes, stolons, and the seeds that fly.

Debbie Flower

Yeah, the kind of Bermudagrass that was used for lawns was chosen specifically for lawns for its color and its more finely textured structure and its delay in seeding. But what we're seeing in our yards now is not that specially chosen Bermudagrass.

Farmer Fred

Yeah, I think the specially chosen Bermudagrass came along later. I think first was the common Bermudagrass that basically took over everything. And then they found a more polite form of Bermudagrass, which I guess is fine for golf courses, something like that. But in your backyard, you don't want it. I have another Bermudagrass type weed here now that I never thought would become a weed. But ha ha ha, the warnings were there. And that's Kurapia. The Kurapia is a modern development based on the old lippia. And if you've ever had lippia, you know that it can spread, as well.

And it's really a tangly, viney mess that grows everywhere but where you want it to grow. Fortunately, it comes up easily. You can't say that about Bermudagrass.

Debbie Flower

No. Because if you leave any part there, it'll sprout, grow.  That's why I like soil solarization. I think of all the methods I've tried to control Bermudagrass, that is the most effective and the most ecologically sound way to do it without having to apply glyphosate multiple times. There are some herbicides specific to Bermudagrass  that may work on other grasses, as well, but whereas glyphosate - Roundup being one brand - will kill the top growth of almost anything and the roots of some things. It won't get all the roots of Bermudagrass because  the stems and roots go so deep. Nor the seeds.

So there are some chemicals available, some pesticides, herbicides listed for control of Bermudagrass, but they will never say that they're going to kill the Bermudagrass. They just say that they will control it. And it usually requires more than one application to get the Bermudagrass under control. And I've used them once or twice. And for me, digging, in combination with solarization, digging was the better choice.

Farmer Fred

You can certainly do that. I did, I had about 2800 square feet of a former lawn that was Bermudagrass and did soil solarization on it. And in the time from that to when we left that property, it never re -sprouted.

Debbie Flower

Wow. And so how far did you have to prep the soil to do soil solarization?

Farmer Fred

You mow it, if it's a lawn. You just mow it as low as your mower can go. And you get it down real real low.

Debbie Flower

And you take the clippings off?

Farmer Fred

Oh yeah, you take the clippings off, definitely. And then you water and you water and you water because you want that water to go down as deep as possible because it's going to carry the heat with it because you're going to put clear plastic over that lawn area and seal the edges so air can't sneak in underneath that clear plastic. Usually they recommend two mil, three mil clear plastic. You can find it usually in the paint department at the big home stores in big rolls that are usually four mil thick. Some say, well, it's going to take longer than that because it's so thick. But still, clear plastic, not black plastic, but clear plastic works. Leave it on six to eight weeks. (sound of barking dogs) We'll wait for the dogs. Are you done out there!?! I'm talking bermudagrass here! Thank you.

Again, to stress, it's important to have moistened that soil thoroughly so that the heat, which can get up to 140 degrees when it's covered with clear plastic, penetrates as deeply as possible because bermudagrass portions can go down several feet and the seeds can last for 50 years. So we lived on this property for 10 years after doing that soil solarization, and then just covered the area with lots of bark to make room for trees, fruit trees, in that area. And Bermudagrass never showed its ugly head again.

Debbie Flower

That's wonderful.

Farmer Fred

Yeah. But I have to say this. We also, in order to dig an area to put the bark on afterwards, we had to scrape off about six inches or so off the top.

Debbie Flower

Because?

Farmer Fred

Because existing soil was level with the concrete walkway, which was next to a swimming pool. So any bark that was in that area, if it rained, would wash the bark into the pool. So basically we had to dig down a little bit and I think that helped a lot, too, in removing a lot of the rhizomes and seeds. And in fact I know it did, because I recall that where we moved the soil to, out in the back 40, it soon became a hill of bermudagrass.

Debbie Flower

Oh wow. So that worked.

Farmer Fred

But the soil solarization process, by raising the temperature up to 140 degrees in the soil, does a great job of not only killing off the Bermudagrass but any possible diseases you might have in that lawn area as well. And apparently the garden good guys that live in the soil, they just go a little deeper until it cools off and then they come back up.

Debbie Flower

I'm curious. You said 2,800 square feet. There is no single sheet of plastic that covers 2,800 square feet.  So how did you cover it without air getting in where the plastic touched or overlapped? Or did you just do gutters, bury the edges of the plastic? How did you do that? How did you get it all covered?

Farmer Fred

Well, a couple of ways we did it. We did it the burying way that you suggest, along the edges. But in the middle where two sheets overlapped, we used the Red Green method, which for those of you that remember that TV show, Red Green was very fond of saying, “You only need two things in life. WD-40 to make things go, and duct tape to make things stop”.

Debbie Flower

So duct tape.

Farmer Fred

And that lasted the six to eight weeks.  Now, because it was rather thin, clear plastic, if it got windy, sometimes it would get rips. And we'd repair it with duct tape. And it was interesting that in some of the spots where the duct tape was there the longest, there was still green growth beneath.

Debbie Flower

Oh, wow.

Farmer Fred

Yeah, just that little bit of shade was enough to keep it going. But it did a great job of of getting rid of the Bermudagrass in the untaped areas. But you did have to stay on top of it because it can come up at any time.

Debbie Flower

Yes, yes, it can. And it can start again from seed that's blown in from somewhere.

Farmer Fred

Oh, yeah. Anywhere. Yeah. So, Gail, in Orangevale, I think Debbie's suggestion is right on. Have your garden this year in pots. And then, put that clear plastic on for six weeks during the hottest part of the summer. Here in Northern California, that's usually from late June through early August, when the sun is at the highest and out the longest, and it's also hot. So if you do it for at least six weeks, six to eight weeks, somewhere in that timeframe, I think you'll be good to go the next year with a garden.

Debbie Flower

Yes. So give it a shot. Good luck. Sounds like a fun project.

Farmer Fred

No, it doesn't.

Debbie Flower

Not the solarization so much.

Farmer Fred

All right, thank you, Debbie.

Debbie Flower

Yeah, thank you, Fred.

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Farmer Fred

Okay, here's your garden to-do list for the day. Spend some quiet time in the yard. Walk, converse, smell, and touch all your plants. Enjoy the texture, the aromas, the color combinations, the structure. Admire the naturally amazing artwork of plant leaves. Check both sides of those leaves for eggs or insects. And if you're checking for eggs or bugs on your plant, make sure that they're the bad guys and not the good guys before you shoo them away.

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Q&A - WHAT ABOUT USING BLACK PLASTIC IN THE GARDEN? WHAT ABOUT USING HYDROGEN PEROXIDE FOR EARLY BLIGHT ON TOMATO PLANTS?

Farmer Fred

We're out here at the Fair Oaks Horticulture Center. I'm watching vegetable expert and Master Gardener Gail Pothour raking bare soil in a raised bed. It looks like you're making a bed to do some planting soon.

Gail Pothour

Yes, this is our bed that's going to have about six varieties of sweet peppers and a half dozen varieties of eggplant.

Farmer Fred

Can I ask you a trick question?

Gail Pothour

Sure.

Farmer Fred

Didn't you plant peppers in this bed last year?

Gail Pothour

No, they were in that bed.

Farmer Fred

Okay, alright.

Gail Pothour

You kind of caught me there. Yeah, I wasn't sure. Yeah, they were in that bed. Okay, because, I know, it's crop rotation and all that. Yes, I know.

Farmer Fred

Yeah, especially with certain diseases.

Gail Pothour

That's right. And we do have diseases in our bed. We have Fusarium wilt and we now have nematodes at least in... it's been identified in two of our beds. So we have to be careful.

Farmer Fred

I imagine “careful” means using nematode resistant varieties.

Gail Pothour

Yes, in fact one of the beds that we know we have nematodes in, we have been following a schedule of leaving it fallow, then solarizing it. So we have about a three or four year program where we're doing certain things. This year we're planting nematode and fusarium resistant tomatoes.

Farmer Fred

Would you like to answer a garden question from a listener?

Gail Pothour

Sure.

Farmer Fred

Oh, bless you. David writes in from Kingman, Arizona. He says, “We had a violent thunderstorm. Soil splashed on the lower leaves of a tomato being hardened off and gave me early blight. The Mojave County Master Gardener saw my pictures and agreed with the diagnosis. So I picked off the lower leaves and treated the plant with hydrogen peroxide. One more reason to avoid taking plants outside too early.” Well, I'll agree with that last sentence, David. And then he says, “A show on black plastic mulch would be good.”

Farmer Fred

Fields covered with black plastic warm soils and prevent soil splashing on leaves. Now David is in Kingman, Arizona and I'm just trying to think of what commercial crops are grown there and the one I can think of is strawberries. And strawberries, have you ever seen a commercial strawberry field? Lots of black plastic there.

Gail Pothour

Or landscape fabric. Well, it's used in agriculture. So you'll find the commercial growers or farmers will use it mostly for warming the soil somewhat. Probably for weed suppression so they don't have to hire somebody to get out and hand weed and to hold the moisture in. Now as far as keeping fungal spores from splashing up onto the leaves, I suppose I would suggest using a thick layer of straw mulch. That would do the same thing. And plus it decomposes and adds some nutrients to the soil where black plastic does not.

Farmer Fred

Yeah, and you brought up a good point. We don't know if he means black plastic. Like solid plastic or the permeable kind that allows air and water to flow through. I don't have as much of a problem with that as I would solid black plastic. I use neither in my home garden because they're a pain in the butt, really.

Gail Pothour

Well, and then if you have them down for a period of time, even the permeable ones plug up. I mean, if the whole point is to keep weeds from growing where you're going to have over time organic matter will sift down into it and plug up those holes and weeds will grow in that. So yeah, I am not a big fan of either black plastic or landscape fabric.

Farmer Fred

Black plastic also doesn't feed the soil. You're not doing your soil any good by having that on there. But with commercial growers using it, they probably replace that black plastic every crop.

Gail Pothour

Right, and they have big equipment that actually lays the black plastic down. And then what do they do with it at the end of the season?

Farmer Fred

Good question.

Gail Pothour

You know, it's just one more plastic item that would fill up landfills. So yeah, I'm not a big fan of it. I like to use an organic mulch myself.

Farmer Fred

I think that's the answer right there. Leave the black plastic to the professional growers and for the backyard gardener, just mulch, mulch, mulch.

Gail Pothour

If you're trying to keep weeds down in your pathways, wood chips are good. Arborist chips are great for that. And in your vegetable garden and raised beds or whatever, I like to use straw. It's not the most beautiful thing, but it does the job. It's fairly inexpensive, although straw bales have doubled in price as everything else has. But it will decompose over time and add some nutrients. And if you have a thick enough layer, it's pretty good at holding in the moisture.

Farmer Fred

I've only been out here about a half hour or so and already somebody brought me to look at a tomato plant that sure looked like it had blight to me. And I'm thinking, yeah with the rain we had it's probably blight. It is not that uncommon and I don't know about David's suggestion about picking off lower leaves and treating with hydrogen peroxide. I mean, we wouldn't recommend it because if you read the bottle of hydrogen peroxide, you will see no information there about how to use it as a pesticide. It is not a registered pesticide.

Gail Pothour

Exactly. It is a sanitizer. And I looked at the bottle of my hydrogen peroxide. It has no reference to using as a pesticide. So I would not recommend using it. And even if you did, I know the internet has a whole lot of sites you can go to where they use do -it -yourself pesticides. But you have to ask yourself, what dilution rate would you use? How would you know how much to put in a gallon of water so that you don't hurt your plant, you don't hurt yourself? And so pesticides that are registered for that use have been tested and they know exactly what the formula is to use. Hydrogen peroxide? I wouldn't know.

Farmer Fred

Show me a scientific study, show me a peer -reviewed scientific study that shows that hydrogen peroxide

cures early blight on a tomato plant. I haven't seen it, but you did come across one document that mentioned it.

Gail Pothour

I did. There was an EPA document. There was no date on it, so I don't know exactly how recent it was. I had a couple or three dates that showed in 1990 whatever it was registered for a sanitizer. And I think the last date was 2006. It said it was registered as a pesticide, but it's an ingredient in a pesticide. So it’s not

the formulation for hydrogen peroxide that you would use as the pesticide. It's an ingredient in the pesticide. And I just ran across that and I haven't had a chance to research it further, but I would be a little leery.

Farmer Fred

Yeah, well, we have to be leery as Master Gardeners and not recommend these homegrown recipes. Just show me  peer-reviewed, scientific studies that are backed by the University of California. I don't have a problem with that at all.  Like I say, show me a peer -reviewed scientific study where hydrogen peroxide is used specifically for early blight on tomatoes and then maybe we can have a conversation. But in the meantime, what would you do if somebody showed you a plant that looked like it had blight?

Gail Pothour

Well, for one thing, I wonder if they're from the South, because typically it takes a humid climate. So I know in the South they have a big problem with that. But if you're in an area that has a lot of dew or rain, you could get it as well. We recommend picking off those infected leaves. And I actually found a couple of articles on the University of California site saying that's the best thing to do is just take off the infected leaves. And then because we typically have a dry climate, it would kind of outgrow it. The early blight, which is an alternaria, can also be carried in seed. So you want to be sure you're getting seed from a reputable company. So, yeah.

Farmer Fred

Yeah, there's that. One recommendation that can help is: if it's a young plant, still in a small container, would be to move it up to a larger container in fresh potting mix that you know is pathogen free and grow the plant in there because with tomato plants, you can plant them deeper than what they were planted originally. You can cut off those lower leaves and plant it up to the final two sets of leaves. Give it another reinvigorating start while also nipping off probably the infected lower leaves that have it.

Gail Pothour

Right, and also be sure that if you're reusing pots, going say from a four inch pot to a one gallon that you're reusing, be sure it's sanitized. So clean it with soap and water. I also dip it in a bleach water solution, one part bleach and I part water. To be sure you're not carrying any potential pathogens into the plant that you're potting it up into.

Farmer Fred

It's Gail Pothour, member of the Debbie Flower Fan Club here, cleaning your pots thoroughly like that. Good for you. I do the same thing now too. So we're all getting into the habit of thoroughly cleaning our old potting equipment. David, I think we answered your question and a lot more. Thanks for writing!

Gail Pothour, Sacramento County Master Gardener,Thanks for your expertise.

Gail Pothour

You're welcome, Fred.

Farmer Fred

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Farmer Fred

Garden Basics with Farmer Fred comes out every Tuesday and Friday. It's brought to you by SmartPots. It's Garden Basics, available wherever podcasts are handed out. For more information about the podcast and transcripts of the podcast, visit our website, GardenBasics.net. And that's where you'll also find out about the free Garden Basics newsletter, Beyond the Garden Basics. And thank you so much for listening.