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jmgrapevine

What's wrong with my Rhoddies?

jmgrapevine
15 years ago

A rhododendron in the side yard has leaves that are all mottled yellow (see pic below). They look like they might have been bleached by the sun. She is about eight years old, about 6' x 6' and had been doing well up until last summer. Last summer the leaves turned color and the blooms were not nearly as prolific as in previous years.

Could it have been stunned by a really hot Atlanta summer the previous year? Should I cut her all back? Any help would be appreciated. Thanx!

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Comments (8)

  • mainegrower
    15 years ago

    This looks like a classic case of lacebug damage. These small pests suck on the underside of the leaves leaving this pale, stippled, unhealthy look. There's nothing you can do about the damage already present, but you can take steps to prevent its reoccurence. Lacebugs are soft bodied insects so spraying with insecticidal soap or summer horticultural oil will protect this year's crop of leaves. Bayer Advanced Tree and Shrub systemic insecticide also works and is poured around the roots of the plant. Your County Extension Service can probably tell you when to start spraying in your area. The systemic can be applied any time. It's also true that lacebug damage is much worse in rhododendrons which receive too much sun.

  • jmgrapevine
    Original Author
    15 years ago

    Thanx so much Maingrower! Sure enough I looked and it appears to be lacebugs(which I have never encountered before). I'm going to heavily medicate her and get rid of those suckers! The six feet of old growth is all damage would it be detrimental to cut her WAY back after the few buds she does have bloom? Again Thank YOU!!

  • luis_pr
    15 years ago

    I left the leaves on my azaleas on the plant when they were infested several years ago. When the leaves finally fell off, I got new leaves and did not need to cut the plant at all. Of course, the shrub did not look nice for a while but when I got new leaves, the plant looked great. If you can wait, I would leave the shrub alone.

  • rhodyman
    15 years ago

    Some azaleas will just about always get lacebug if planted in a sunny location. By moving to a more shaded area you can eliminate the problem naturally.

    Some azaleas are naturally resistant to lacebug and can be planted in full sun. The following azalea cultivars have resistance to azalea lace bug: ´Dawn,´ ´Pink Star,´ ´Ereka,´ ´Cavalier,´ ´Pink Fancy,´ ´Dram,´ ´Seigei,´ ´Macrantha,´ ´Salmon Pink,´ ´Elsie Lee,´ ´Red Wing,´ Sunglow´ and ´Marilee.´

  • ninaweeds
    15 years ago

    I have a mature Rhododendren that hasn't produced flowers since i bought my house 3 years ago. I have pruned it lightly twice, any suggestions?

  • luis_pr
    15 years ago

    You need to determine if the shrub is producing flower buds (that are then getting killed) or if the shrub is not producing flower buds at all. If you do not know, you can look for seed pods but here are some general suggestions.

    * Winter can kill the flower buds if the shrub is planted out of zone. This requires that you know the variety of rhododendron that you have.
    * Early or late frosts can damage or kill the buds. It is ok if this happens rarely but not three years in a row.
    * Prune after flowering and before flower buds start to form in July.
    * Do not fertilize with high nitrogen fertilizers and stop all fertilizing in July so new growth and buds do not get killed by early frosts. Make sure that lawn fertilizers do not regularly end up near the shrub as some of these are high nitrogen fertilizers.
    * Make a soil test and check nitrogen, phosphorus and potassium leves.
    * Make sure it gets some sun (dense shade is not good for bloomage), make sure the buds are protected from wildlife (think deer or squirrels) and make sure that soil moisture levels are adequate. Keep the soil moist, not dry or wet, especially after buds form around July and especially during dry winters in places where the ground does not freeze.

  • ninaweeds
    15 years ago

    Thanks for the info, while I was doing yard work yesterday I did notice some promising looking buds on the Rhoddie, but they seem to be on the lower half . The buds up top are small and look to be leaf buds. I do have two huge red maples planted directly infront of the rhododendren, so sunlight is limited. The soil around it is also very dense with root and almost impossible to dig.

  • rhodyman
    15 years ago

    You seem to have hit on the main problems: shade and root competition.

    Roots: Rhododendrons don't compete well with other roots since rhododendrons have shallow roots. If you are willing to put in the effort, the best thing to do is dig a trench well outside the drip line of the rhododendron down about 10 to 12 inches and cut every root that crosses the trench. Then install metal edging to keep the roots from coming back. I had to do this because of nearby walnut trees. Walnut roots are toxic to many other plants including rhododendrons and azaleas. I saved my rhododendrons.

    Shade: The ideal situation for rhododendrons is what is called high shade. Cut off the lower branches of the maple trees. Too much shade will prevent flower bud set. It will give you a beautiful green plant.

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