321 Spring Rose Care Basics - Diseases and Insects

Show Transcript

GB 321 Spring Rose Care Basics TRANSCRIPT

Farmer Fred  0:00

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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

From now through Mother’s Day, roses will start putting on their first and best show across the country. What do your rose bushes need to get off to a good start in early Spring? Master Rosarian Charlotte Owendyk of the Sierra Foothills Rose Society talks about getting ahead of early spring rose pest and disease problems, before they can do too much damage to those brilliant first blooms. She also discusses the best fertilizers and irrigation systems to use to help thwart pest and disease issues, as well, for your rose bushes in the coming months.

It’s all in Episode 321 of today’s Garden Basics with Farmer Fred - Spring Rose Care Basics

We’re podcasting from Barking Dog Studios here in the beautiful Abutilon Jungle in Suburban Purgatory, it’s the Garden Basics with Farmer Fred podcast, brought to you today by Smart Potsand Dave Wilson Nursery. Let’s go!

Farmer Fred

We like to answer your garden questions here on the Garden Basics podcast, Gail in Napa. California writes in and says, “Hi, Farmer Fred. I have three tea roses planted in a nice sunny spot with good airflow. I planted them about seven years ago, and one of the roses always has strange colored leaves. They range from yellow to motteled red. It still blooms but the flowers are small. The other two bushes don't have the same problem. And after I did some research, I'm thinking this rose has the mosaic virus, even though I bought it from a reputable nursery. Can you tell if I have this virus? If so, should I destroy this bush? Thank you for your great show. It is extremely helpful.”

Gail, thanks for writing in. And thanks for sending the pictures of what your rose leafs look like. And I'll be posting that picture with today's episode. So let's call in a Master Rosarian and get the lowdown on this mosaic virus. We are talking with Charlotte Owendyk, she is a Master Rosarian with the Sierra Foothills Rose Society. And Charlotte, I've been getting a lot of questions about this from people asking about the funny yellow striations on their leaves, on their roses. And it seems to go back to this virus.

Charlotte Owendyk  1:44

That's correct. The Rose Mosaic Virus, it's yellow or white, it's kind of mottled on the green leaf. The picture is a perfect example of that. And it's funny, it usually exhibits in the spring and the fall; but in the hot weather, it disappears. It gets masked by the green chlorophyll on the plant. So you might think it's gone. But it's not. I think the listener has done an excellent job of figuring out what she has. And she's already come up with the solution because some roses are  affected more by Rose Mosaic Virus than others. And she's saying it's got smaller blooms and less blooms, because of that. She's saying I need to shovel prune, and that's a term used by rosarians, when we want to get rid of a rose plant, we do shovel pruning. She needs to shovel prune. As a rule, I don't have any plants with Rose Mosaic Virus in my garden.

They have not shown how it moves from one plant to another. They haven't found a vector, which could be an  insect that moves it plant to plant. They thought at one time it was caused by pruning, but they couldn't demonstrate that it was caused by pruning. So you know, she has one plant, and she's had it for seven years. And none of the other plants in the area have shown that virus. So that's an indicator, it's not moving due to your pruning process. The other thing they at one time  thought: maybe it's root to root transfer. But they did some tests on that. And they couldn't prove that either. So what is normally done and the University of California Davis had a program where they make sure that because a lot of our roses are on rootstock. They do what is called virus index rootstock. They sell rootstock that is virus free to all the rose growers, and they plant and put the rose that we  want on that root stock. And, therefore you get virus free plants. But sometimes there's a problem. And I don't know when it happens. Like I say, I got a brand new rose and I won't mention who I got it from. It had rose mosaic virus, I mentioned it to the nursery, and I got a replacement. I was lucky enough that it showed before I had a year go by. So sometimes it just shows up. Like I say if it's really hot, you'll never see it. And sometimes it doesn't have it but as the plant gets older, sometimes you see more evidence of it. My recommendation is shovel prune it and get something else. Get a newer variety of Rose plant that is probably more resistant to other diseases and one that you'd like. There's so many good roses on that have been introduced into the market.

Farmer Fred  4:32

What if you really liked the flower on this particular rose? I got an email from one gentleman who said, “Yeah, I've had a rose with the rose virus and I've had it for eight years, but I really enjoy its blooms and I'm keeping it.”

Charlotte Owendyk  4:44

You can do that. A lot of people do that. And since they can't prove how it transfers, it'll be just on that one bush. As I mentioned earlier, some roses can tolerate that virus more than others. They're still pumping out the blooms and they're still growing well. And if that bush wasn't blooming as good and didn't look as healthy, then he probably want to get that get rid of that bush and get another one, you can get the exact same rose. Again, if it's available on the market, it probably will not have the virus at that point. And then you have a good bush.

Farmer Fred  5:18

The University of California talks about the rose mosaic virus. We'll have a link to that page in the show notes. And they say that this virus infects roses through budding, grafting, or rooting cuttings from infected plants. And that roses infected during propagation can be symptomless until after they are planted and begin growing in the landscapes. And a lot of people who grow roses have gotten rather fond of starting new roses from cuttings. It's a fairly easy process. But you really don't want a cutting of a rose that has this virus.

Charlotte Owendyk  5:52

That's correct. Yeah, I got a couple of cuttings starting because I have some bushes that nobody else has at this point and one is called Pink Poodle. And as you know, I have some poodles. But this rose has no virus. I'm a responsible Rosarian.

Farmer Fred  6:09

The University of California also says that virus-infected plants may grow more slowly, produce delayed or fewer flowers, and become more susceptible to frost damage. But the severity of damage varies depending on what kind of rose it is.

Charlotte Owendyk  6:25

Yeah, depends on the variety. Yeah,  it basically reduces the amount of chlorophyll in the leaves. So it's going to be a little of a slower grower. I don't know if other people have noticed this, but if you have a variegated plant versus one that's totally green, or a plant that has a chartreuse coloring versus regular typical green, that plant will grow slower because it has less chlorophyll.  You can plant, let's say, feverfew, which is an herb, it produces Daisy like flowers, you have the gray variety of green leaves, and then you have a chartreuse color. The chartreuse one will be about at least six inches shorter and a little bit smaller in stature than the green one. So that's because it has less chlorophyll. Chlorophyll uses the sun's light and water to produce the carbohydrates, the sugars, the plants needs to grow. So it's less vigorous. And you'll find that in the case with all variegated plants, too, because it has less chlorophyll, it has more white. And let's say it's gray in the leaf. So that's a general rule of thumb. So I want something that's not as big, something that I look to see if  they have a variegated variety. Sometimes  they've done the breeding, and it's still green, and it's slower, and smaller in stature, but sometimes you can do it. And that's nature's way of, of slowing the growth. It's just, it just works that way.

Farmer Fred  7:57

Nature can be tricky, too. The University of California points out that some infected roses exhibit no damage symptoms, and boy, that would be kind of risky.

Charlotte Owendyk  8:07

Well, that's why they have this program where they provide index root stock. What they do is they take pieces of the material, the root, and they actually use an electron microscope, or they probably do something a little bit more sophisticated. Now  at one time that's how they used to do it. And they actually would check to see if there's viruses in the cell.

Farmer Fred  8:31

Gail in Napa also pointed out that yes, she has that yellowing, strange color, but also a red mottled color that you can see in the picture that I posted with this episode. Is that common as well?

Charlotte Owendyk  8:43

It varies with the plant. Yes, you can see that it's  just not normal. You have different colors of leaves.  I've got some plants that the leaves are kind of a ruddy kind of a bronzy reddish, but it's all one color. And these are mottled. That's the key. Or the color is mottled  and it's not the whole leaf.

Farmer Fred  9:06

So, again for Gail, learn that great Rosarian euphemism; shovel prune.

Charlotte Owendyk  9:14

I remember the first time we talked about the term, shovel prune. We shovel prune for various different reasons. Sometimes we don't like the bush, sometimes the bush is not perfect, or sometimes it's a disease magnet. It's sometimes that we didn't realize that bush  we ordered from a catalog has lots of thorns. We don't like lots of thorns, we get rid of the bush. So there's a lot of different reasons.

LYDA ROSE VS. NASTURTIUM VINE

Farmer Fred  9:39

We have one more question from a listener about their rose. And they wrote in and said, “Over the winter a nasturtium volunteer decided to climb through my Lyda Rose rosebush. My wife likes the way it looks now. I think it might be harming the rosebush and want to take it out. Can you solve this dilemma for us? It really is kind of a nice structure.”

Charlotte Owendyk  9:59

That's beautiful. The picture you sent me  of that nasturtium, it  is almost like a climbing nasturtium. And you can't even see the rose for the nasturtium.

Farmer Fred  10:09

The branches are sticking above the nasturtium.

Charlotte Owendyk  10:13

maybe six inches above. That's all.

Farmer Fred  10:18

I think the owner of the rose also hasn't had a chance to get in there to prune it because of that nasturtium.

Charlotte Owendyk  10:23

That's correct. Well, light is the big factor. In fact, I'm in my dining room and I'm looking outside at a Lyda Rose.  I thought you might have a Lyda Rose.

Farmer Fred  10:31

I do have a Lyda Rose.

Charlotte Owendyk  10:34

Lyda is a fairly large shrub rose, because mine is about four feet, maybe three and a half to four feet tall. I had the same problem but I instead of a nasturtium, I had the Roxanne geranium do that to a shorter stature rose. It was a red rose that only gets about three feet tall and three feet wide. And Roxanne, was which was planted next to the rose, decided to grow up through that rose. Ingrid Bergman's the name of the red rose, a beautiful rose, by the way. I couldn't see the bush and it didn't bloom very much. Because there's a little thing that happens when  you can't see the bush. And all you see is the leaves of the nasturtium or the Roxanne. That means the leaves or the rose are not getting any sunlight or not enough sunlight. And  roses like to be in full sun. And if they don't get full sun, they don't bloom. They don't get enough sunlight. So it gets smothered, so to speak. It's like putting a blanket on top of your rose.

Farmer Fred  11:38

But eventually the nasturtium, I'm sure. will be removed.

Charlotte Owendyk  11:44

And that's fine. What I would probably do since that nasturtium has gone crazy. It seems like it's my understanding some nasturtiums will climb like that, I’d probably remove that one. And at the base, pull it away, do some cleanup on the rose,  open up the center and do some cleanup pruning on that. Then fertilize the rose, and it'll be just fine. And if you want to put in nasturtiums down there, put in a nice variety of nasturtiums. I got some seeds I want to try this year in my yard. Just put them in there and it'll be a nice ground cover, underneath the Lyda Rose and then you'll have the rose. And you'll tell the nasturtium not to do that. Well, actually if you have a climbing nasturtium, let it grow itself somewhere else. Give it a little something to climb up on. It'll be happy.

Farmer Fred  12:33

I have a funny feeling that this rose owner is waiting for this nasturtium to go into decline so he can say to his wife, “I’ll remove this now. The nasturtium is fading away because it's getting too warm.”

Charlotte Owendyk  12:45

Yeah. Well,  they usually die back in the winter.

Farmer Fred  12:50

Around here, nasturtiums can last through the winter.

Charlotte Owendyk  12:53

Yeah they do. My mother had nasturtiums underneath a tree down in Southern California, it was basically a ground cover.

Farmer Fred  13:00

But one way to hasten the decline of the nasturtiums would be to make some snips at the base of the nasturtium.

Charlotte Owendyk  13:05

You got it. Snips will will do the trick. Yeah.

Farmer Fred  13:13

Okay. All right.

Charlotte Owendyk  13:18

You could do a couple snips and just keep a few of the nasturtiums in the Lyda rose. But give the Lyda rose some breathing room, because it's not seen sunshine and it's not happy. I don't know what the foliage looks like underneath it. I'm not quite sure where it is, but it's probably got maybe some mildew on it depending on how wet it is. It may have some black spot, and it's not putting on any blooms. So why have a rose that you basically are not enjoying? Put the nasturtium  on some sort of trellis and don’t let your roses be the trellis, because the rose is not getting any sunshine.

Farmer Fred  13:56

Since you brought it up. Let's talk about other springtime maladies of roses that just might be going on. I mean, when I think of roses in the springtime, the first thing I think about are aphids.

Charlotte Owendyk  14:06

Oh, aphids. I was strolling a neighbor's garden of mine. And  she says, “I haven't seen any aphids”. And as we're walking through her garden - she has 300 Roses - we finally found three or four.

Farmer Fred  14:20

Yeah, but are there any buds on those roses for the aphids to glom on to?

Charlotte Owendyk  14:23

Oh, yeah, there are tons of bugs and tons of fresh new growth. And I haven't seen any aphids in my yard. But I've seen ladybugs already. You know, I have a no-spray garden, and she does too. It’s all between the balance between the predators, the good guys, and the bad guys.

Farmer Fred

Amen to that.

Charlotte Owendyk

Yes. I'm always rooting for the good guys. And I have a hummingbird feeder. I have a Finch feeder. I have a lot of little tiny birds. Do you realize hummingbirds love aphids?

Farmer Fred  14:58

I did not know that.

Charlotte Owendyk  15:01

Yeah, they eat a lot of aphids, it’s part of their protein in their diet. I have a lot of companion plants. Something is always flowering in my garden, the Anna hummingbird in California overwinters here, we don't lose them like some other parts of the country. So you can have hummingbirds year round. Aphids can be born pregnant, you know. If you get the first couple of aphids, you can manage to keep them from exploding. That's what used to happen, we used to spray or we'd use a lot of chemical fertilizers. That's the other thing that a lot of us have, I do not put any chemical fertilizers anymore because it produces a lot of succulent growth which is easier for the various different insects to suck juices out of the cell or do various different things. It's easier for fungus to break through the cell wall and then establish themselves. So I have less disease pressure, I have less aphid pressure than before. It's actually less work and it's kind of nice to see. Occasionally I'll see something and I'll do a  mechanical control for example. We get the rain and  lots of times the best time of year to get Blackspot is when you get a warmer rain in the spring and then that's the time you get some black spot damage. Well, I have three roses. For example, my Julia Child tree roses have a significantly higher  bush part. It is at least three feet above the ground. They don't get any black spot; very seldom do I get black spot up there. But my little miniature roses that are right close to the ground, get black spots. So this year after I prune, I put a layer of fir bark, a soil conditioner that can be used as a mulch, around the drip line of all my roses as I pruned. I don't have any black spot, except for ones I didn't prune or didn't have a chance to put that fir bark around. I feel so proud of myself.

Farmer Fred  17:13

Before we skip to the fungus, black spot,  one more thing about aphids. I know  it works for me and I love to do  this when I see them all clustered on a bud. I love to spray water on them.

Charlotte Owendyk  17:26

Oh yeah, a shower. And wash them down and then all the other things on the ground will gobble them up. Yes.

Farmer Fred  17:33

Now, for the sake of the purists out there, we should point out that when you say “chemical fertilizers”, what you really mean are “synthetic chemical fertilizers”.

Charlotte Owendyk  17:40

Correct. I use organic fertilizer, which is easy. It is fir bark, it's all organic materials. I even use earthworm castings.

Farmer Fred  17:52

And I'll have a link in today's show notes to  one of my more more popular talks, called “Plants that attract beneficial insects”, because it not only talks about the plants that bring in the garden good guys, I have pictures of all the good guys’ life stages. So you can see what a teenage Ladybug looks like. It doesn't look like the adult Ladybug.

Charlotte Owendyk  18:12

Oh, no. It's actually really cool. Like, it looks like an alligator. Exactly. Only more colorful.

Farmer Fred  18:19

Wearing a San Francisco Giants warm up jacket.

Charlotte Owendyk  18:23

Yeah, yeah, it's really cool. Yeah.

Farmer Fred  18:25

The teenage ladybugs, they're the ones that eat aphids.

Charlotte Owendyk  18:27

Oh, yeah. The praying mantis, however, is a weak link in the world of garden good guys (they tend to eat both good guys and well as bad guys). I got the soldier beetles, lacewings, spiders, minute pirate bugs. There's tons of those and like I say, don't forget the hummingbirds.

Farmer Fred  18:44

Yeah, really. I have a list of beneficials for roses: I’ve got  tiny parasitic wasps, minute pirate bug, lacewings, ladybugs, Soldier beetles, which are also called leather wings; Syrphid flies, predacious mites, thrips and spiders.

Charlotte Owendyk  19:00

Yep. They're all good guys. And the thing is, you when you don't spray insecticides and stuff, the good guys keep the bad guys at bay. And there's a balance that occurs. Occasionally, it gets a little bit out of whack. But  I'd like to suggest using mechanical controls, like hosing things off. That works very good for spider mites in the in the heat of the summer because they are underneath the leaves. So I just wash the underside of the leaves, several times during a week or 10 days, and they're gone.

Farmer Fred  19:32

If we're talking about blackspot, that's a fungus and that requires free water to reproduce, which means you don't want to keep your leaves wet.

Charlotte Owendyk  19:40

You got it. Well, the thing is do is water in the morning and Make sure the leaves are dry by nighttime.

Farmer Fred  19:46

Right. And tell the rain to stay away at night.

Charlotte Owendyk  19:50

And we're looking at some rain tonight. I love rain. I do the newsletter for a couple rose societies. And when I have to work on a newsletter, and it's beautiful outside… I'm not happy.

Farmer Fred  20:03

So what do you do for black spot?

Charlotte Owendyk  20:05

After I prune, I'm very religious about taking all the plant material and toss it in the trash can. All the leaves from the previous season, they probably have some black spot spores on it , or it's dropped and  it becomes leaf litter. And that's a source of black spot. I do not do anything for black spot per se, because I'm a no-spray  garden. This year, as I mentioned, I put on the soil  a kind of a light weight mulch around the drip line of  my roses, because I know there's black spot spores in the soil. And when the water droplets hit, it splashes up and that's how it gets infected. I don't have any of that because of that mulch layer. So I figured that was a good mechanical way of dealing with that. If I do and I had a black spot. The reason I did it is I noticed over a couple of years, I kept on saying well, I'll put compost down. Well, I never got time to put  compost down. It was after the rains, and that’s when compost is heavy. So I'm just gonna get some bagged stuff and put that around my roses, as I have black spot. C'est la vie. I know as soon as the temperatures hit 85 here in California, the black spot will disappear because the leaves are dry enough. So I just tough it out. Make sure that  the soil has been enriched enough so the rose plant can put out a whole new set of leaves.

Farmer Fred  21:31

And I would think, too, that those leaves that have black spot or for that matter even rust, you don't want to put in a compost pile, unless you have unless you have a hot compost pile.

Charlotte Owendyk  21:41

Yeah, hot compost. That's the key. You want to try to clean your garden of all the residues, any fungal disease. If you have fungus on the leaves, and you see the evidence of that, you want to get rid of all that debris and put it in your trash cans. Do not put it in your compos, it gets dirty. It has fungal spores on it, the type that infects plants. There's other things that are like that. For example, I shovel pruned a couple of roses that have a bacterial disease and I put it in a plastic bag and I toss it. There's a few other things that you have to do that to, especially with rust.

Farmer Fred  22:18

I mentioned that and rust is usually seen as orange pustules on the underside of the leaves.

Charlotte Owendyk

Pretty cool, long, thick.

Farmer Fred

Yeah, it is. And then that too, is also spread by a water.

Charlotte Owendyk  22:31

Yep. Sometimes if we have a wet autumn, that's when I see it in my yard and I have one rose that gets rust every spring. It's an old garden rose. iI’s just very susceptible. I just pick off the few leaves that have it and throw them in the trash.

Farmer Fred  22:48

There is a problem with roses, a fungal disease that could be a warm weather problem as well. And that's powdery mildew.

Charlotte Owendyk  22:55

Yes. It's water transmitted. And I read up on that, it is interesting. There was a Berkeley professor of plant pathology and he said, it likes a little bit of water on the leaves. But if you hose the leaves - and they have a lot of powdery mildew in the Bay Area - If you host the leaves off before 1030am or so, a lot of the spores that have landed on the leaves won't have time to infect the leaves. You have reduced the amount of powdery mildew you have in your roses. I thought, well that's interesting, but you know, it's so dry here and in the valley. We don't usually have to worry about that.

Farmer Fred  23:30

So if you do live in a humid, moist area, then the one thing you don't want to do is to have your lawn sprinklers hitting the rose plants.

Charlotte Owendyk  23:39

Yes, you're much better off to have drip irrigation system around your roses. Roses like to get a  water shower. They do like that. But the key is to make sure it's dry at night. It's when it's wet for an extended period of time that problems occur.

Farmer Fred  23:57

What is the difference between powdery mildew and downy mildew?

Charlotte Owendyk  24:02

Powdery mildew is more on the surface. And Downy Mildew does get into the leaf itself. And it actually distorts leaves more.

Farmer Fred  24:14

From what I understand about downy mildew, It's got the fruiting bodies on the underside of the leaves, which is how to tell the difference between that and powdery mildew.

Charlotte Owendyk  24:22

Thank you for reminding me. It's been a while, because I have no exposure. You see that in the Bay Area again, right? Where you have  the right temperature and humidity. It needs a fairly warm temperature at night and the appropriate amount of humidity, and we still get it if it's humid at night. It's usually cooler here so we don't see that here much in the valley. Whereas in the Bay Area, the temperature isn't as cold and it's more moist. That's where you see more Downy Mildew. So it's it's really temperature dependent.

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SPRING ROSE CARE BASICS, PT. 2

Farmer Fred

Let's get back to our conversation about spring rose care tips with Master Rosarian Charlotte Owendyk. One interesting development that can happen on your rose leaves throughout the spring and summer - and it sends new rose growers into a tizzy - is “what are these half circles disappearing from the leaves of my rose plants? What's going on here?”

&