rhododendron

mestoApril 21, 2007

Some of our rhododendrons are dying, and there seems nothing we can do to save them. The leaves go brittle and look dead, then drop off. One variegated type flowered in February, too early, then got the frost and started dying. We have heard there is a virulent new disease that affects Rhodo's and oak trees, perhaps this is what we have, there are oak trees all around!

HELP!

Mesto

Thank you for reporting this comment. Undo
luis_pr(7b/8a Hurst, TX)

Hello, Mesto. Oak trees are good trees to grow rhododendrons under; other good trees are magnolias, some pines and dogwoods. On the other hand, you have "bad" trees like walnut, butternut, ash, beech, elm, some maples, poplar, pin oak, sycamore, black walnut.

Walnut and butternut trees have roots that produce a toxin that can kill rhododendrons and other plants. The others trees do not produce toxins but have characteristics that make it difficult to grow rhododendrons under them. For example, some of the trees are surface rooted like rhododendrons so there is intense root competition for moisture and nutrients. Others attract insects that cause problems.

I suspect your recent weather may have done them in. Do you see any evidence of bark split as a result of sudden cold weather following a spring thaw? Late spring freezes can cause the sap to re-freeze and rupture/break the bark. Note that, sometimes, the damage is not visible until later in the spring/summer.

Other things that I was wondering while considering other causes.... How long have the rhododendrons been in this location? How much sun do they get? If you insert a finger in the surrounding soil to a depth of 3 inches, does it feel dry, moist or wet? Do you see any indication of insects in the top or bottom of the leaves? Can you describe how the leaves are dying?

Luis

    Bookmark   April 21, 2007 at 1:28PM
Thank you for reporting this comment. Undo
morz8(Washington Coast Z8b)

Have you had reports of Sudden Oak Death in your area?

"The most common symptoms on shrubs such as rhododendron are twig dieback and leaf spotting. Blackened shoots with or without foliage attached are typical of twig dieback caused by P. ramorum. Leaf spots are brown in color with diffuse, fuzzy margins."

There are other explanations though....it's not uncommon for rhododendrons that are planted with an intact compacted rootball to fail in about their third year (when the roots have circled each other to the point of strangulation)...You don't say how mature your plants are.

Drought can cause parts of rhododendrons or entire rhododendrons to die. Bark split as was mentioned above...After some severe winter temperatures here I would expect to see symptoms of bark split but I don't know what type of winter you had.

Insects that could cause the damage you describe are stem borer, and weevil larvae feeding on roots.

Here is a link that might be useful: Sudden Oak Death

    Bookmark   April 22, 2007 at 3:16AM
Sign Up to comment
More Discussions
Good site to order blue?
Hi, I am looking for a west coast nursery that sells...
kjmm1
Greer Gardens
Greer Gardens appears to be enjoying the last days...
kristincarol
Tiny white specks on Rhododendron?
I have a 6 year old rhododendron (Virginia Richards)...
gardenbug
Anybody out there have luck with Rhodos in Southern Arkansas?
Looking for any feedback from Houzz readers who have...
Rusty Empire
Galloping gardeners strike again
Yikes! My two wonderful dogs have a completely different...
cyn427 (zone 7)
Sponsored Products
Rhododendron 27" Spinner
$430.00 | Horchow
Martha Stewart Living Craft Storages & Organizers Craft Space 3 lb. Short
$24.00 | Home Depot
Martha Stewart Living Craft Storages & Organizers Craft Space 3 lb. Tall
$34.00 | Home Depot
Rhododendron 30" Spinner
$400.00 | Horchow
Red Rhododendron Framed Print
Ballard Designs
Martha Stewart Living Carts & Stands 31 in. H Rhododendron Leaf Cart With Pull
Home Depot
Martha Stewart Living Tables Rhododendron Leaf Corner Craft Table 0795200600
Home Depot
Martha Stewart Living Craft Storages & Organizers Craft Storage 2 lb. Ribbon
$9.00 | Home Depot
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™