HELP w/ Photinia - Leaf Spot Disease

jreincke(Z8 Oregon)August 1, 2005

Hi,

I know my photinia has leaf spot disease. I am not sure how to treat this as I have read my different opinions. Do I use a spray on it? When do I spray it? Should I trim some of the branches away so it has room to breathe? I believe they were planted too closely.

Also now it doesn't have many leaves on it at all and the leaves that it does have, has the leaf spot. It does show a few new sprouts so I don't think it is dead. Any hints tips, etc would be great on how to take care of this shrub. We have 6-7 in our backyard near a fence as a hedge.

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rhizo_1 (North AL) zone 7

If you do a good Google internet search on photinia leaf spot, you will find out that this is a very common problem. Here are a few of the cultural factors that can make it worse:

Planting too closely together. Over fertilizing. Shearing to maintain a hedge.

You sound as if you've neglected this problem until the plant is in serious shape. To be truthful, at this stage and even long before this, the typical recommendation would be to remove the plants entirely and plant something else.

Expecting to these plants to recover without rather extensive treatments with chemical fungicides is wishful thinking. This is a disease that WILL not go away with simple cultural practices, but must be treated chemically and repeatedly so.

If this were my hedge, it would have been removed quite some time ago. However, if you wanted to mess with it a while longer, you could try a drastic rejuvenation pruning, and commence on fungicide applications on a regular basis. Cutting your hedge back to 6 inch stumps will force all new growth to emerge from the bottom of the plants. If these photinia have not been too stressed out (and I truly expect that they have), an enormous amount of new growth will emerge. This will have to be sprayed according to the directions of your various fungicides. You should plan on purchasing two or three products so that you can rotate them. Your extension service can help you with making chemical suggestions. You may have to spray as often as once every ten to fourteen days.

Red Tips, under normal conditions, respond remarkably to rejuvenation pruning. If you decide to try this procedure, do not fertilize. In your location, you could get away with doing this at this time of year. Do a search on rejuvenation pruning, also, so that you know I'm not making it up. Many folks just can't believe that such a drastic measure is possible.

    Bookmark   August 1, 2005 at 8:55AM
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gardengal48

The above is excellent advice. But you will find enthusiasm for chemical approaches in the very ecologically conscious PNW few and far between. Our climate is just very encouraging to the development of photinia leafspot as well as a huge assortment of other fungal problems. Many reputable nurseries in the area have simply stopped selling problematic plants like the photinia in favor of less disease prone selections.

My primary suggestion would be to remove the plants and replace with something less inclined to require the degree of maintenance and attention photinia will - Pacific wax myrtle (a native) or Portuguese laurel, for example. Otherwise, I would also encourage the rejuvenation pruning and any cultural improvements before resorting to chemical controls, which will only delay the inevitable anyway.

    Bookmark   August 1, 2005 at 9:31AM
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jreincke(Z8 Oregon)

The leaf spot has just occured since May of this year. These plants were inherited to us when we bought the house earlier this year. We had a really wet Spring.

I've done a lot of research on the web about leaf spot and it all says the same thing and that is to spray. It just doesn't say with what and when to do it.

I looked up rejuvenation pruning as you suggested and that sounds very drastic. These plants are well over 15 feet tall and to take them down to nothing sounds drastic. There isn't any other way of killing the disease?

Thanks
Julie

    Bookmark   August 1, 2005 at 11:56AM
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jean001(z8aPortland, OR)

The time to apply the spray is early spring, this to protect the newly developing shoots. In other words, it's too late now.

For now, rake up and discard all dropped leaves, and avoid watering such that the leaves get wet.

And you can try the rejuvenation pruning suggested by rhizo. Even so, understand that our climate is very beneficial to this, and other, leaf diseases.

    Bookmark   August 1, 2005 at 1:30PM
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juliang

My red tips are 5 years old and some are 10 feet tall. Their trunks are several inches in diameter. I cannot use any of my pruning tools to perform rejuvenation pruning. I would need a saw to get thru these trunks. But is a saw OK?

Yes, they have leaf spot again for the 3rd Spring in a row. And yes, I have tried different kinds of, expensive, off the shelf fungicides only to see it come back again.

I want to keep them - it's heck to dig them up or buz them flat to the ground. And besides, their root system has probably already dominated everything underground for many square yards most likely making it harder for replacement shrubs to take root.

So, I am interested in rejuvi pruning. But with what and how do I prune such thick trunks? And is it worth it?

    Bookmark   April 30, 2007 at 8:37PM
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brizzyintx

Pretty old post here, but I'll chime in with my two cents worth as I seem to be winning the battle. I, too, wanted to keep them because they provide somewhat of a sound barrier, and I didn't want to go through the trouble of digging them up. So here's my story:

My red tips had probably never been trimmed in the 13 years since the house was built. When we bought it last spring, they were all 10-15 tall, and at least 10 feet in diameter - all comming from a two foot cluster at the base. We live in a subdivision in Texas, so backyards aren't that large to begin with. Oh yeah, and I have about 20 of these things spaced about three feet apart.

Well, I starting cutting. And cutting. And cutting. Down to about seven feet tall. I got about half of them done last summer. Almost immediately, all the new growth started showing leaf spot. (Evidently, new growth is a lot more suseptible to leaf spot than mature leaves are.)

I did some research and found that fungicides containing chlorothalonil or myclobutanil are effective. I tried spraying the existing leaves, but there were so many, I don't think I ever got complete coverage. This leaf spot is very "contagious" so it doesn't take much for it to just get passed back and forth.

This spring, I went all out. I cut everything down to about 4', and stripped every single leaf off. As the new growth started coming in, I started spraying religously. Every other Saturday, I mix up a couple gallons and go to town. So far, no spots. And you have to make sure you keep any fallen leaves picked up, as well.

It's a little expensive. I think a bottle of the fungicide is about $12 and lasts about a month. Not nearly as expensive as the websites I've seen about leaf spot led me to believe it would be.

That's my experience. I'm by no means an expert, but I did a lot of research and it seems to be working. It is a lot of work, though. I have probably 40 hours invested in lopping, sawing, cutting, and bundling. But if you have an easier way to remove brush than setting it at the curb, that will help. I think I spent more time bundling than I did cutting. The spraying is the easiest part.

My method of cutting was pretty haphazard. They were so dense, I just started cutting branches as I saw them. I lopped off all the small branches with loppers first. (Buy a GOOD set. You'll need something pretty heavy-duty.) Then the bigger braches that were left at the end, I cut with a chainsaw. There's no real method to it, and I think it's pretty hard to screw up. Red-tips are very resilient.

Well, good luck. I hope this helps.

    Bookmark   August 24, 2007 at 1:42PM
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rewbarb

I browsed through these posts looking for reference to blackspot disease on English Laurel,and red spot on my Portuguese laurels, worried that my privacy hedge would be gone when all the leaves dropped, revealing my neighbors revolving junk pile, jammed up against their 5 year old diseased trunks! I can sleep tonight knowing that I don't have to treat them with expensive environmentally toxic chemicals in a battle for property line beauty, and small bird sanctuary. All I need in my gardening tool box is, a flame thrower, a 16" chainsaw, and a few leftover branches, just in case!

    Bookmark   March 28, 2009 at 10:22PM
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brizzyintx

Wow. I forgot all about this one. It's funny that it should come back around after all this time.

Well, the red tips did pretty well all last year. Then this spring, the spots came back, and came back hard. So... Every single one got cut down last weekend. Problem solved.

Now, off to dig up 14 stumps...

    Bookmark   May 20, 2009 at 6:53PM
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triaxt32_hotmail_com

Our hedge (inherited) got this disease really bad after the severe summer and severe winter, as did everyone's around town. After doing my research, I concluded we had to get rid of these 15 bushes completely. But after we hacked them down and dug up the stumps, I am seeing everyone's skeleton Red Tips coming back to life and am starting to regret it. Did I chop mine all down for nothing? Or will everyone's bushes get it again?

    Bookmark   April 2, 2010 at 9:23PM
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brizzyintx

I've never seen Red Tips recover completely and continue to be disease-free. Not ever with regular applications of chlorothalonil or myclobutanil. I do not have a single regret over tearing all of mine out - except maybe that I didn't do it sooner.

    Bookmark   June 12, 2010 at 11:06AM
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progressiveenlightenment_live_com

Don't mess with the chemicals mentioned here. They will murder photinias. Neem Oil has worked a miracle on my 19 photinias, which I too use as a hedge to block out traffic. One good thing to say about photinias is that, despite being prone to disease, they are very strong and can endure heavy manipulation. Mine are still young, 4 years old, and it's inevitable that they get sick in winter. But once the sun comes out in early spring, I cut off ALL infected leaves so that only new leaves and buds remain. In a month, those new leaves will be fully grown and lots of new ones will be on the way. You don't have to kill them and plant something else. But you need to be more courageous than usual to break the cycle of infection. Stay away from the chemical treatments, which at the very least will prevent flowering.

    Bookmark   April 5, 2011 at 11:46AM
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gardengal48

Repeated shearing or pruning to remove affected growth is far more likely to prevent flowering than the application of fungicides to control Photinia leaf blight. And recommended fungicides will NOT "kill" the photinias any more than the fatalities caused by repeated defoliation each season as a result of this disease. Fungicides do not kill plants if applied properly - they kill fungal pathogens.

Photinia leaf blight can present differently and with varying degrees of severity depending on where the grower is located. In moist climates or humid summer areas, this disease can be devastating to the shrubs and will ultimately kill them. If this is the case where you live -- and this thread is 6 years old, so who knows if anyone is reading -- then replacing these shrubs with something less troublesome and without the need for frequent chemical intervention is highly recommended.

There is a very good reason this shrub is no longer recommended or sold by better nurseries throughout much of the country.

    Bookmark   April 5, 2011 at 4:25PM
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