Why 1 out of 4 rhodies so sick?

Westford, MA(Zone 6a)

I planted four Rhododendron 'Cunningham's White' in the spring of 2004. They have all been moved twice (last time in the fall of 2007). In 2006, we had a borer problem, which we treated, and I have seen no further sign of insect castings or weak branches since.

Late this winter all four looked vigorous and healthy, but as spring has worn on, one began to look quite ill.

I'll post some pictures, including shots of her healthy sisters.

Note: In this shrub border, the sick plant is the one that gets the most sun (4-5 hours). The other three get filtered sunlight to full shade, but the sick plant looked great least year in exactly the same spot.

Thumbnail by peony8
Westford, MA(Zone 6a)

Here's the poor plant's crown. Nothing there, not even new growth.

Thumbnail by peony8
Westford, MA(Zone 6a)

A distance shot of some brown leaves. Ironically, those wilting leaves are next to the healthiest part of the plant. ;-)

Thumbnail by peony8
Westford, MA(Zone 6a)

A closer shot of the sick leaves.

Thumbnail by peony8
Westford, MA(Zone 6a)

For comparison, here's an image of one healthy sister. You probably can't see the missing branches from the crown, which I removed after the borer issue.

Thumbnail by peony8
Westford, MA(Zone 6a)

And the other two, which look vigorous and show new growth.

Thumbnail by peony8
Westford, MA(Zone 6a)

Any input on what might be wrong with the sick one, and what I should do? I have purposely not fertilized it this year.

Might a severe pruning bring it back?

Or should I just yank it out, plant it in the woods, and put a new shrub in its spot? Maybe a rose will be happy there.

Saugatuck, MI

I don't know if I can be much help, I have had rhodies for quite a few years since my neighbor has a huge rhodie nursery. Each May after her wholesale orders are out she opens up to the public for 2 weeks selling off her "seconds" which are still very nice and large. I'm convinced success with rodies totally depends on the weather. I have some that were beautiful last summer and this year look terrible. My neighbor tells me they hate cold winds (I'm in Michigan) which we had alot of last winter and they don't like wet feet. Well, in Dec. which was most unusal we had 5 in. of rain in 2 days time and my worst looking ones stood in soil that was probably too wet. Your photo does not look any worst than some of mine and my neighbor says to just plant another one in front of it. Because of the nursery there are many many homes in our area with rhodies and the best ones you see are ones growing next to a building where they are protected and then they get large and loaded with blooms. Well, mine never are. I don't fertilize in a big way because they are all planted under pines and so the soil is right for them and she says they really don't need fertilizer. Altho some varieties can take dense shade it seems most benefit from a little sun.
So if you had a hard winter I'm sure that is your problem and we can't control that.

Westford, MA(Zone 6a)

This past winter was very hard on rhodies. In the spring a friend who is a garden designer asked if I had any bronzing. I didn't know what that meant until I started driving around in my car and noticed all the rhodies that were completely dead in spots, but in strange formations, such as from the crown only, leaving the outer edges green and healthy.

It was really sad to see these stately, tall rhodies that would have to be pruned down to a nub.

We had a series of warm days and then deep freezes well into December, and then we had an ice storm that put many parts of New England in a state of emergency. All up the coast, as well as inland, many people were without power for *weeks.* And right after that warmth that preceded the ice storm, we went into a week of below freezing temps.

We had no tree or roof damage, and all of my rhodies looked fine in early spring, but I can't help but wonder if that one plant endured a lot of stress from that weird winter. It's not as sheltered as the others (which are shaded by a cherry tree), and it sits in the northeast corner of my backyard.

None of my rhodies have ever bloomed prolifically, but I have moved them twice since I purchased them in 2004. I didn't know then that if you dig up the roots, you're supposed to prune the foliage back, so these guys have been totally abused by me and by borers, and yet they refuse to die.

I could pull up and replace it the ailing one, but I think I'll give it a hard prune and see how it does next spring.

Hurst, TX(Zone 7b)

I also think it may have had a case of severe exposure to winter, peony8. When that happens, the leaves wilt, the edges become brown (sometimes get distorted too) and some yellowing follows due to additional infections to the leaf. Winter damage sometimes takes a while to become obvious; the plant looks fine when leafing out but then the leaves begin to brown out. For example, there appears to be bark split damage on the second photo. Protection from winter winds and winter sun may be needed when the winter is as bad as you described.

You can prune any dead stems now but discontinue pruning after the end of June. Pruning after flowering and through June will protect the Spring 2010 flower buds that the plant will start to develop ususally around July-ish.

Do not fertilize on or after July in order to prevent damage from early Fall frosts either. Too much fertilizer, also known as fertilizer burn, will cause these symptoms too although they will be broadcast throughout most of the plant. If the condition of your soil requires that you fertilize, try using something like Holly-tone or cottonseed meal (about 2 weeks after your avge date of last frost and again in June). Transplanted plants should not be fertilized on their first year to prevent complications from transplant shock. Limit the use of fertilizers to coffee grounds, liquid seaweed or liquid fish (but discontinue these at the end of June too). This year, just mulch it well since rhodies basically feed off the decomposing mulch. Maintain around 3-4" of acidic mulch at all times.

If you decide to do heavy pruning, be careful when working around the shrubs since their roots are shallow and usually located in the top 4" of the soil.

Luis

Westford, MA(Zone 6a)

> Protection from winter winds and winter sun may be needed when the winter is as bad as you described.

How is this done? Do I wrap the plant in burlap this winter? Or put one of those A-frame stand sover it?

> You can prune any dead stems now but discontinue pruning after the end of June.

I was considering pruning the entire plant back by at least a third, not just the dead stuff but the live growth, too -- in order to preserve the shape. I don't mind if I lose blossoms next spring, as long as new healthy growth springs up from the crown.

I have a huge back of Holly-tone. Would it be best to fertilize now and wait to prune for a couple weeks or prune and fertilize right after? Or does it matter, as long as I stop fertilizing in June?

I will be careful of the roots. Thank you for the caution. I know this plant gets walked over/around more than the other three because there are several shrubs and a tree behind it that I need to get to. I should remember to water from the other side of the fence and tread lightly when weeding.

Would it make a difference to the roots if I put down a few slate stepping stones?

Hurst, TX(Zone 7b)

There is no "one way" to protect from winds and sun. Some people transplant shrubs to another place, others place some sort of barrier/screen (e.g., a burlap screen) and yet others plant a larger evergreen shrub nearby.

With elepidotes (the large leafed rhodies), prune above growth joints, a visible location where growth began on a given year. Dormant growth buds are located at the growth joints so prune just above the joints. In between joints, there are no dormant buds so cutting there will not trigger growth buds.

With lepidotes (the small leafed rhodies and azaleas), you can prune anywhere you pretty much want as there are invisible dormant growth buds everywhere.

I would proceed with pruning now and not bother fertilizing unless your soil has a nutrient defficiency that requires this. Rhodies normally feed off the decomposing mulch; they rarely require much in terms of fertilizers. Since you are going to stress the plant by pruning heavily, do not add any fertilizers until next year.

As for slate stepping stones, I cannot comment as I rarely disturb the area around azaleas and rhodies. In other words, I have never done it or seen it done. The size/weight of the stones might be an important factor as it will compress the roots and the soil somewhat. These roots I am talking about can be as thin as hair in some places.

Westford, MA(Zone 6a)

luis_pr, thank you!

Based on what you have said about protection, I am a little surprised this rhodie did so poorly. Though it is the most out in the "open," behind it is a large pieris and a chain-link fence that is, by now, covered in ivy about 1/4 of the way up. On the other side of the fence is a dogwood and a neighbor's evergreen. I also have three clethra back there, but they probably aren't much of a windscreen in winter.

I'm attaching a picture from last spring, when we first installed this shrub border. (Note, the rhodie had been moved from another location the fall before, and I was surprised that it bloomed).

The damage you see to it from the crown was removed branches from borers the year before that.

I do know what you mean about the roots. I was really surprised when I dug it up 1) how easy it was and 2) how delicate its root system was.

(I really need to get new pictures. I can't believe how much things have grown!)

Thumbnail by peony8

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