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annld

Sick Rhodies

annld
16 years ago

Is anybody else having a tough time with their rhododendrons this season? Mine look really sickly. I don't know if it was the late winter or what. One of them lost a couple of branches after the leaves turned brown and curled up, and all of them have some yellowish leaves. The plants are only a few years old, so they aren't very big. Anybody have any thoughts on this?

Comments (10)

  • earthlydelights
    16 years ago

    i'm looking forward to hearing because mine are terrible. i only have three. one has buds. one looked like i wanted to, but didn't. under parts of the bush are dried out, but nothing like the one that was out front. i did dig that one out and move it to another spot. i decided what was hurting it was the ice melt/salt that would get washed off the steps. i don't know if that was the cause, but the lightbulb went off and i decided time to get it out of there and boy did that one look sick to it's every branch and leaf.

    maybe you might want to post on that particular forum if you don't hear from anyone here...although rhodyman might chime in and have some excellent ideas.

    maryanne

  • rhodyman
    16 years ago

    For many of us, this past winter our plants took a beating with the very unusual winters some of us had with warm weather followed by late freezes. They have what is more typical of drought damage but in this case was caused by the warm weather followed by late freezes. It causes Botryosphaeria dothidea which causes leaves to turn dull green and then brown and roll and droop. Cankers form on branches which may girdle the branch.

    This is the most common disease of rhododendrons in the landscape. A typical symptom of this fungal disease is scattered dying branches on an otherwise healthy plant. Leaves on infected stems turn brown, then droop and roll inward. These leaves often lay flat against the stem and will remain attached. The pathogen can infect all ages of stem tissue through wounds, pruning cuts, and leaf scars. Heat, drought stress, and winter injury can increase disease incidence. Cankers on branches can gradually grow through the wood until the stem becomes girdled. Diseased wood is reddish brown in appearance. Discolored wood viewed in longitudinal cross section often forms a wedge that points toward the center of the stem, and the pith may be darker brown than the surrounding wood.

    Sanitation and applying a fungicide such as metalaxyl (Subdue) after pruning my provide some control. Plants should be grown in partial shade, with mulch and kept well watered during dry periods. All dying branches should be promptly pruned out in dry weather and all discolored wood should be removed. Plants should also be protected from rough treatment during maintenance activities to prevent unnecessary wounds.

    Here is a link that might be useful: Rhododendron and Azalea Troubleshooting

  • annld
    Original Author
    16 years ago

    Thanks, Rhodyman! Very helpful!

  • earthlydelights
    16 years ago

    i'm happy to report that the rhody i moved from the front of the house, that might have gotten hit with ice melting salt is looking better and putting out new green/shootes.

    the one on the side of the house, i sprinkled just a tad bit of lime around the base of it and soaked it in and that one is also putting up new shoots.

    i noticed yesterday on my bike ride, that a home on a neighboring street, his is completely in bloom and it's gorgeous. here's hoping the one of mine that has buds will burst open and reward me.

    maryanne

  • bulldinkie
    16 years ago

    Whenever my azaeleas and Rhodys,pines etc are looking rough I water with product from miracle grow.Its called miracid its a gray & blue box.

  • rhodyman
    16 years ago

    Miracid is more of a problem than a cure. It is high in nitrogen which is exactly what rhododendrons and azaleas don't want. It is a soluable product so that it has no lasting effect.

    The best rhododendron and azalea fertilizer is Holytone. It is best to apply it once in the spring at half the rate recommended on the package.

    Rhododendrons and azaleas are not heavy feeders and in fact some such as R. albiflorum, the native rhododendron on the west coast, may die if fertilized. So the conventional wisdom, is don't fertilize if the plant looks healthy. I know my soil is deficient is phosphorus, and needs a little help with the acidity, so about every 5 years I fertilize with a mixture of Holytone, Magamp (a slow release phosphorus rich fertilizer) and powdered sulfur. The sulfur helps keep the soil acidic.

  • eibren
    16 years ago

    There was an article in--I think--the NYTimes not too long ago about the effect that global warming is having on the rhododendrons further South. The author came to the conclusion she could no longer recommend planting them in her climate. I guess we are just one step behind that point.

  • bulldinkie
    16 years ago

    I saved a many a azaeleas,rhodys with miracid.......I even use to put pine needles under the shrubs every year for the acid.All bloomed gorgeous every year.

  • bulldinkie
    16 years ago

    Miracid is liquid one time shot till you do it again,holly tone is slow release.If I have a problem I want to end quick before I lose the bush miracid does that.Its sprcifically for acid loving plants.Thats the difference.

  • rhodyman
    16 years ago

    Liquid fertilizers don't solve as many problems as they create. Use of such liquid fertilizers will:

    1) cause soft vegetative (leaf) growth that will freeze kill.
    2) cause a shallower than normal root growth which will drought kill.
    3) inhibit the formation of flower buds.
    4) have a very transient effect on soil pH.
    5) inhibit hardening off for cold weather.
    6) create tender tissue that will sunburn.

    On the other hand using a good balanced slow release rhododendron and azalea fertilizer that is applied once in the spring such as Hollytone will:

    1) promote strong branches and good bud formation.
    2) promote deep roots which will withstand drought.
    3) promote the formation of flower buds.
    4) have a longlasting effect on soil pH.
    5) promote the hardening off for cold weather.
    6) promote hardening of tissue so it won't sunburn.

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