Pests and diseases

A Rose Virus?!

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For some of my longer time readers, you may remember this photo from last year.

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This is this year. And sadly at least one or two more of those roses is going to have to go. What’s happened? A nasty virus called rose rosette.

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There aren’t really any good photos of what this virus does to roses. It is spread by a microscopic mite–so no chance to see the damage until after it occurs.

Last year the roses looked beautiful. They came out of dormancy this winter looking stunted, with witches’ brooms and oddly twisted foliage and I started ripping them out.

After I filled a whole dumpster with them, I realized that I hadn’t gotten them all, which is how I was able to get a few photos. So I have to go back and take out at least 2 more.

Obviously we will not be replanting roses here, which is kind of a shame because they were happy. Oh well. At least the roses got the virus and not us!

Drought Stressed Evergreens

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It’s been a tough few years here in the northeast. I won’t re-hash. I’ve talked about it often enough.

But as tough as it’s been on the people who call this region home, it’s been even tougher on our plants. And the plants are finally showing us that they may have had enough.

I started to notice trouble with Eastern white pines (a native plant, incidentally) in early May, after a very dry winter. What’s interesting is that I wasn’t just seeing signs of distress on these plants near streets–as some of the experiment stations were reporting–but I was seeing it all over the place and often several hundred feet back from the road where “winter salt injury” couldn’t possibly be a factor.

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These two trees are in a neighbor’s yard. They are several hundred feet from the road and in a mixed planting of other evergreens and deciduous trees and shrubs. So clearly this is not “salt injury. ”

Here is a “fact sheet” from the University of Massachusetts on the Eastern white pine situation. Even they can’t quite figure out what’s happening, although they have some speculation.

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More recently I am seeing injury to spruces. They’re either dying from the top down or from the bottom up–it scarcely matters really.

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And then of course there are the ground cover junipers. These are often susceptible to blights like juniper twig blight caused by a couple of different fungal diseases (hard to think of fungi in droughts but actually several of them flourish in the heat). This is my juniper horizontalis with twig blight. It’s going to have to be removed.

The Spoiler is in denial.  He thinks the dead parts can just be cut out. If he would like to try, more power to him. This juniper covers about 100 square feet.  It will leave a huge hole in this garden.

So what is going on? Is it just drought? Is it drought, made worse by warmer winters? Does it matter?

Any time a plant is stressed, it is susceptible to disease and pests. Drought is certainly a stressor, and prolonged drought would be an extreme stressor to evergreens, because they can’t shed their leaves the way deciduous trees can.

I have already cut back many of my “drought stressed” (and therefore either browned or diseased) perennials for this season. That will allow them to conserve whatever strength they have left and put it into coming back next year and other years. No point in watering (either supplementally or if we happen to get any rain) diseased or browned plants. Let the water go to the “good” plants that remain.

But with evergreens, they can’t shed their leaves protectively. So what we may be witnessing after several summers of less than ideal moisture is the evergreens that simply can’t cope. This past warmer winter may also have been a stressor for the trees as well.

Time will tell about whether these trees can recover. If not, New England backyards and forests may never be the same.

 

Are Knockout Roses Disease and Insect Proof?

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Yellow Knockout rose

This is a yellow Knockout rose. While the foliage may look pretty good, look closer. There’s yellowing foliage beneath the new growth and insect chewed foliage, and even some diseased foliage. What gives? I thought Knockout roses were bullet proof?!

Well, yes, so did I. And in my yard, most of them have proven to be. But certain roses, including this yellow Knockout (and Home Run, a rose that is supposed to be an Earth Kind rose but that is just about dead in my garden–go figure!) just don’t grow well.

That the yellow Knockout should be less vigorous makes sense. Yellow roses in general are weaker. It’s just a known genetic wrinkle. I’m not quite sure why that variation exists, but it does. And as yellow roses go, this is still a darned good one!

But contrast it with the Original Knockout, which towers over my head and which I have to whack back every year–including this “polar vortex” year.

Original Knockout

There’s quite a difference. Even my pinks, while not quite this vigorous (because I stupidly planted them under a tree which has now overtaken them!) are not spotted or insect eaten.

But oh well. I do love yellow so I’m willing to put up with a little imperfection. How else will folks know this is an organic garden?

Tomato Testing, Grafting and Tasting

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An article in the “Science” section of last week’s New York Times about the search for a better tasting tomato (isn’t that vegetable’s holy grail?) led me to muse about this season’s tomato crop.

While overall, it has been a slower season than usual for me, not helped, of course by the fact that deer browse stunted all my tomatoes, there are certain things that have been successes.

The first thing that has been a success, at least in terms of disease resistance, has been the grafted tomatoes. I can’t say that they have grown or produced fruit any quicker than the un-grafted varieties (but that may be due to the deer browse problem and not due to any fault of the tomatoes themselves).

I planted 3 types of tomatoes, and I planted a grafted variety next to an un-grafted variety. In each case, I gave the grafted variety slightly better positioning in the garden so that it got slightly better sun. It didn’t seem to make much difference–but that again may be because the deer ate the tops off at a crucial time in late June.

Where the grafted tomatoes really shone was in disease resistance. By late July there was nothing left of the un-grafted ‘San Marzano.’ It had completely succumbed to a disease or blight–I wasn’t really paying attention because I was focusing on warding off the deer at that point. I suspect it was a disease, however, since none of the other tomatoes in the garden succumbed and blight, from what I understand, is highly contagious.

The grafted ‘San Marzano’ is still going strong and producing fruit–so that is ample reason to speak up for the grafted tomatoes. At least in my garden, every year there is some reason that something attacks the tomatoes.

This year was the perfect storm of attacks on the tomatoes too–or the “everything that can go wrong, will go wrong” year. In June it was the deer and the over-abundance of rain (if there can be such a thing) leading to disease.

In July, it was still the deer, and disease.

In August, I found hornworms, something I don’t think I’ve ever had–or if I have, I’ve had them with the beneficial wasp larva on their backs so I could remove the worms, sequester them somewhere safe and let the larva do their work. This year, no such luck. No larva to be found. And I’m such a sucker, I still can’t kill the big lugs. I just cut them off the plants and put them way over in the woods. They probably die anyway, removed from their food source. But I figure if they have a chance of transforming into a moth, they ought to have it.

So needless to say, with all that going on, there haven’t been a lot of tomatoes yet. I’ve got a lot of green ones on the plants but I haven’t had a lot of red ones. But there’s still time. And if all else fails, I know a few great methods of ripening the green ones. I’m just not into fried green tomatoes and I don’t have the patience to make my Dad’s green tomato relish.

Some Black-Eyed Susan Wisdom

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black-eye susan leaves

For a few years now, I’ve been saying that black spots on black eyed susans (rudbeckia species) were not a fungus. I even had seen insects on my black-eyed susans that I was sure were causing the damage–the four-lined plant bug.

I am not necessarily backing down from that diagnosis–but in researching some diseases for another post I came across some information about some diseases of rudbeckia. And I now think it’s possible that mine have at least a combination of insect damage and a leaf spot disease known as septoria.

Prior to this, I only thought of that disease as affecting tomatoes.

Of course, every extension service Bulletin I’ve read suggests spraying some strong chemical fungicide or copper to control this problem. I am willing to do neither, just as I am unwilling to do anything to attempt to treat for the four-lined plant bug.

This fact sheet from the University of Minnesota (one of the few with relatively good photos) has a decent discussion of fungal diseases affecting Black-eyed susans. They note that for their climate, septoria leaf spot is relatively common and the others are not.

So how do I plan to proceed? Basically the same way as always–with very good sanitation in the fall to prevent any over-wintering of “whatever:” fungal spores or insect eggs.

I’ll thin my black eyed susans a bit to increase the air circulation–that can never hurt.

But I don’t do any overhead watering. So I can’t stop that. What nature does is a different story! And since this June she’s dished out a lot of “overhead watering” (4th wettest June on record) I suspect that this year, at least, my black spots could indeed be some sort of fungal issue!

A Rose That Didn’t Make The Cut

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Flower Carpet flowers

Flower Carpet rose

A rose that I am traveling around with, but that I really don’t recommend, is Flower Carpet Pink Supreme.

I have a soft spot in my heart for the Flower Carpet roses. I planted the original pink one (Flower Carpet Pink) when we got married and it flowered and bloomed gamely even after it was over-taken by a Japanese maple. I seem to have a habit of planting roses too near trees and not remembering that they will eventually spread out to engulf them. My bad.

Anyway, this game little rose kept growing and throwing up ridiculously long canes for awhile and The Spoiler would remark, “Look at that tree blooming.” But eventually, I took pity on the rose and composted it.

It seems hard to believe that after that story I wouldn’t recommend this rose. It’s not that it’s a “bad” rose. It’s just that what’s come along since is so superior that there’s really no reason to grow this rose. This rose, because it was the first, doesn’t have the disease resistance of the later roses. And really, why struggle with black spot if you don’t have to?

There are valid reasons to grow this rose (other than sentimentality, of course). It comes in some colors that none of the others yet do. And let’s face it, we gardeners get into snits about our color schemes sometimes!

Flower Carpet Amber is a peachy color with yellow tones. Flower Carpet Pink Splash is a pink and white bi-color–no other series has a bi-color. And the Flower Carpet Yellow is especially vibrant.

So if you are looking for some unusual colors in a relatively easy care roses, give the Flower Carpet roses, in their distinctive pink pots a try. Just be sure to give them plenty of air circulation to avoid disease!

The Black Spots on Your Black-Eyed Susans Are Not a Fungus!

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For years, I’ve listened as speakers, other gardeners and even nursery and landscape folks all advised homeowners that the black they were seeing on their black eyed susans (rudbeckia species)was a fungal disease and that they should spray them with a fungicide.  This advice was given in wet seasons and in dry, without seeing the plant and without any further diagnostic inquiry.

So a few years ago, when black spots started showing up on my black eyed susans, I decided to take a closer look.  I knew darn well I wasn’t going to spray with a fungicide for 2 reasons: first, what I was seeing looked nothing like a fungus, and next, fungicides only work if you begin spraying before you have a problem; they sure don’t solve the problem once you have it.  So no point in spraying once the black leaves are already there.

So the first season I watched.  The leaves started out in a small patch, got a little worse, and then stopped.  Next season, same thing:  Small patch of black leaves that gradually spread for about a week or so and then stopped.  This is not fungal behavior, folks.  Fungi do not stop on their own. They just keep going until the leaves are completely covered and the leaves fall off.  Think of powdery mildew on lilacs or, worse yet, on phlox leaves or think of black spot on roses.

Last year I discovered the culprit.  It’s a beetle.  And beetles being what they are, it wouldn’t stay around for a photo.  I was lucky that I got a good enough look at him that I was able to make an ID.  It looked enough like a cucumber beetle (elongated body, and stripes, but larger head and dissimilar enough that I knew it wasn’t a cucumber beetle) that I was able to pin it down to the general family of leaf beetles–but that’s about all.

And in true leaf beetle fashion, it sucks the underside of the leaf–much like that caterpiller-like rose sawfly larva.  Then, when the sun comes out, it burns the top of the leaf, the leaf turns black, the gardener goes to the garden center and says, “My black eyed susan leaves are all black” and voila!  He or she gets sold a fungicide!  Amazing how that happens.

This damage, by the way, is totally consistent with insect damage–it has a definite cycle: in other words, begins slowly, gets worse, and then ends when the insect life cycle is over.

So don’t be the next victim!  Since this is only going to occur for about a week, try to live with it.  Since this is a beetle, my guess is that an insecticide with spinosad would kill it–or, you can do as I do.  Once the worst of the infestation has passed, pull off the affected leaves and get on with your gardening without harming any good bugs in the process.

What’s Eating My ConeFlowers?

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Now this isn’t a pretty sight, is it?  You try so hard to grow native plants for  the wildlife and you wind up getting the wrong kind of wildlife–something eating the flowers!!!

Well, don’t despair.  Although these flowers don’t look pretty, their wildlife value is still intact–it’s the brown “cones” in the middle that are actually the “flowers”–the purple-y pink petals, or rays around the edges are just there to provide attraction and a better landing surface.

As you can see in this photo, the flower has lost all its rays, practically, and yet the tiny sweat bee that’s landed on it is just bright yellow with the pollen it’s harvesting.  So all is not lost.

There are actually several things that could be eating the coneflowers but in my garden I saw them last year when they were on my black-eyed susans (rudbeckias). For years my black-eyed susan leaves would get some sort of blackish mottling on the leaves that I always thought was a fungus.  It affected my golden oregano too.

Then last year I was working in the garden and I brushed the golden oregano and something flew out!  So I investigated closer and found a small beetle that looked very similar to a cucumber beetle, but with slightly different markings.  All my bug books didn’t have just exactly that but in it, but I was able to isolate the family to the leaf beetle or chrysomelid family.

This is the family that gives us all the baddies: cucumber, asparagus and potato beetles, the lily leaf beetle, and the flea beetle.

Because these beetles are so hard to spot, and because they fly, control is difficult.  It’s not as if you can just knock them into a cup of soapy water as you can with Japanese beetles.  I just tolerate the damage because this is a wildlife garden and I do not want to use anything, even an organic control, that might affect the bees.

A chemical control, particularly a systemic, is most likely your best bet against these should you be willing to go that route.  But remember, you are growing native plants that will be visited by birds, bees and butterflies so consider carefully whether you wish to use a systemic that will be eaten by everything that feeds on this plant!

By the way, Japanese beetles also eat coneflowers and black-eyed susans–but I’m convinced if you had those, you’d know it.  They’re not hard to spot!

Japanese Beetles

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They’re baaaack!  Yes, it’s that time of the summer when these little foreign invaders, the japanese beetles (popillia japonica), invade our gardens and lawns and occasionally our homes.  It seems to me that they’re a wee bit early this year, but then again, so is everything else.

So what is an enlightened gardener to do?  Well, the conventional wisdom is that those traps that they sell are really only good for monitoring an infestation–or attracting them to the yard.  They do not trap all the beetles.  Folks joke about putting the traps on adjacent properties which is fine if your neighbors don’t object but I just don’t see that being practical in most cases. So the beetle traps are not really the answer we were looking for.

A good resource for a thorough understanding of the beetles can be found at this USDA pamphlet.  It describes how they got here, how they can be controlled through integrated pest management, what chemical controls are effective if you choose to use chemicals, and which plants are most susceptible to damage, and some alternatives.

As for me, I’m fortunate that the birds keep the grub population in control and without grubs you can’t have a lot of beetles.  So I normally don’t do anything about these beetles at all (secretly I think they’re kind of pretty, but that’s only because you are looking at the sum total of the population on my property at the moment).

If the population does get out of hand, I go out early in the morning or later in the afternoon–when they’re sluggish–and knock them into a cup of soapy water.  When they’re dead, I spread them out for the birds to eat.  Everybody wins.

Wilting Black Lace–A Follow-Up

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I was away last week and while I was, I had a comment on my post called “Why Is My Black Lace Wilting?”  The very perceptive commenter named Kim had noticed the same thing in her Black Lace and had cut it open and found small yellow worms.  When she called her garden center, they recommended a systemic insecticide.  She chose to remove her plant instead.

From the time I got her comment until the time I actually got to examine my Black Lace it’s been almost 2 weeks–and I was quite pleasantly surprised to see how well it had recovered from its wilting.  Nevertheless, I went down, cut off a branch that still showed some residual evidence of wilt, and started probing (and by the way, there were still some lovely red aphids on it this time!)

I found this evidence of a borer tunnel–and many like it.  I never actually saw any borers, but they may be long gone, based on the recovery I am witnessing in the shrub.

Once I cut open the stem in several places, this is what I saw.

This is borer damage in an apparently otherwise healthy stem.  There is clear evidence of an insect residing in the stem at one point, but no damage to the stem or the leaves that were on it, and no wilt on the branch (because I wanted to show the close-up of the insect home, I didn’t show the leaves so you’ll have to take my word for that).

This, on the other hand, is a stem that had been damaged and was showing some wilting.  The inside shows some evidence of frass, or chewing debris left behind by an insect.

So that’s all I can tell you about my experience with the Black Lace stem borers since they appear to have left my plants.  I will be more alert for them next season and I thank Kim for sharing her experience so we can all learn from them!