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Tuesday - March 25, 2008

From: Pflugerville, TX
Region: Southwest
Topic: Compost and Mulch, Diseases and Disorders, Propagation, Seeds and Seeding, Shrubs
Title: Problems with Eves necklacepods (Styphnolobium affine)
Answered by: Barbara Medford

QUESTION:

Mr. S-P, I urgently need your advice regarding two Eve's necklacepods that appear to be dying. They are in two completely different areas of my yard. One began leafing out and then the leaves shriveled. The other has not leafed out, and the stems of both are turning black. They survived last year's monsoons, but I do suspect poor drainage, as they are both on spots that get lots of runoff (although it doesn't puddle there). Could this be the problem? Can they be pruned way back and moved? Do you know what pathogens they might be susceptible to? I use no poisons in my yard.

ANSWER:

You may have managed to stump Mr. Smarty Plants. In the first place, this plant is in our Native Plant Database as Styphnolobium affine (Eve's necklacepod) , but in several other reference materials it was called Sophora affine, thus making it more nearly related to Sophora secundiflora (Texas mountain-laurel). We know a little more about the Texas Mountain Laurel-that it is very difficult to transplant, with very long roots that are easily damaged, causing the plant to go into shock and die. You didn't say when your plant was put into your garden, or if it was a transplant, but if the same conditions hold for the Eve's necklacepod, that could be causing your problem.

Styphnolobium affine (Eve's necklacepod) must have a well-drained planting spot or it will get chlorotic, indicating an iron deficiency, causing a diseased condition in green plants marked by yellowing or blanching. This USDA Plants Profile shows the counties in Texas where the plant is known to grow; since Pflugerville is in the northern part of Travis County, we can assume that your plants have a right to be there. We also know that Central Texas has the challenge of caliche, clay dirt and lots of rocks, and a very alkaline soil. Alkaline soils can deny the access of the plant to trace elements, such as iron and magnesium, which the plant needs, and thus, chlorosis.

So, we haven't really found the answer to your question or a solution to your problem. You are probably correct that poor drainage and last year's very uncharacteristic rains have caused the problem. One of the best ways to correct these deficiencies is to incorporate humus, as in compost, into the soil. Sadly, it's probably too late to do that for your trees. Right now, watch and wait may be the order of the day. If they do die, replacing them by propagating from seed, and planting them into a well drained spot with lots of organic material might give them a better chance to succeed.

Styphnolobium affine