Digging In - Straightening Your Ginko Tree, Brown Camellia Blooms

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By Scott Aker
Special to The Washington Post
Thursday, December 18, 2008

Q I've noticed that a young ginkgo tree planted in the past two years is leaning and has developed a kink in its trunk. How can I straighten it out?

A Your ginkgo is probably young enough to adjust and grow into a straight-trunked tree over time. All trees have some ability to straighten their trunks when confronted with a snow load or some other factor that causes them to bend or lean.

The tree senses the imbalance and grows more wood on the leaning side than on the opposite side. In cross section, the annual growth rings on such a tree will be lopsided: thin on one side and very thick on the other. The pressure of the differential growth causes the trunk to straighten. When the trunk is nearly vertical again, the production of compression wood will ease and the annual growth rings will return to the normal pattern of concentric circles.

That said, it is important for the lowest part of the trunk to be vertical because the upper part has greater flexibility in righting itself. Since your tree was recently planted, you might be able to replant it so the bottom part of the trunk is perpendicular to the soil surface. You can still do it before the ground freezes.

I get loads of buds on my camellia shrubs, but the petals turn brown, starting with the outside edges. When fully open, the blooms are completely brown except for the center. What can be done to prevent this?

Your camellias are being blighted by fungus. Botrytis, Ciborina and Sclerotinia fungi can cause the petal tissue to turn brown and mushy if warm, wet weather coincides with bloom in late winter or early spring. If Botrytis is the cause, fuzzy spore bodies quickly follow. The damage caused by Ciborina and Sclerotinia may be mistaken for freeze damage. Heavy frost can damage camellia petals, but the petal tissue won't be mushy, and the damage will appear suddenly as soon as the tissue thaws.

Good sanitation is the best way to control the disease. Clean up all the fallen leaves and petals under your camellias to remove the source for disease next year. If you want to be sure that your camellias aren't damaged by fungi again, you can spray them just as the buds are starting to show color. There are a number of effective fungicides.

I have two types of celandine in my garden, but I need help distinguishing the native plant from the Chinese species. I want to encourage the native plant and remove the others.

The lesser celandine is a rampant invasive plant with glossy, kidney-shaped leaves and luminous yellow flowers. It hugs the ground and rarely grows taller than six inches, while the native plant, the celandine poppy, can reach three feet in favorable conditions. Both plants tend to be dormant in the summer.

Celandine poppy has leaves that are a bit hairy, dull in color and dissected. The characteristic that most easily distinguishes it from other plants is its sap. Break off a leaf and you will notice that the sap is bright yellow. It was used by Native Americans as a dye.

Scott Aker is a horticulturist at the U.S. National Arboretum.


© 2008 The Washington Post Company

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