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Thursday - July 03, 2008

From: Puyallup, WA
Region: Northeast
Topic: Non-Natives, Transplants
Title: Yellowing leaves on non-native Betula pendula
Answered by: Barbara Medford

QUESTION:

I live in Puyallup, Washington. I purchased and planted a weeping birch on June 21, 2008. For the first few days all seemed well and the tree seemed to be settling in to its new home. Less than eight days later, the leaves began yellowing pretty much all around the tree. I'm extremely concerned about the health and ability of the tree to survive. The leaves haven't fallen to the ground and the tree is still flexible. Can you please tell me what I can do to save my tree?

ANSWER:

Once again, we are seeing the result of "plant first, ask later." At the Lady Bird Johnson Wildflower Center, we constantly urge the use of native plants, because they are adapted to the conditions in which they live, and resistant to pests and diseases. This is a classic example. Please read this article from the USDA Forest Service on birch selection and care. Note the mention of Betula pendula in the chart on various species of the Betula.

Because this tree is a variant of the European white birch, and therefore not in our Native Plant Database, we have extracted this information from the TreeHelp.com website on Young's Weeping birch.

"Care
Transplanting should be done in early spring. Fertilize once or twice per year with a specially formulated fertilizer for Birch trees. Water to keep the soil wet or moist a few inches below the surface. Prune to maintain shape, but do not prune during the growing season. Rather, wait until the end of the growing season in the fall. This is especially important because the bronze birch borer is active during the spring and open pruning wounds are inviting to them.

Problems
Susceptible to birch leafminer and highly susceptible to bronze birch borer.

Iron deficiency may occur, especially in alkaline soils. This is evident by yellowing of the leaves. This problem is refered to as Chlorosis and can be treated by introducing iron tablets into the soil."

Obviously, you cannot go back and un-transplant your tree, and do it in the early Spring, but that was probably the biggest mistake. Any plant will go into transplant shock when it is moved, and moving it at the wrong time of year, especially in the summer, is going to be the biggest shock of all. At this point, it needs tender loving care. Begin by getting iron tablets into the soil immediately. Yellowing leaves indicates chlorosis. The birch does best in a slightly acidic soil; if the soil is alkaline, the roots are unable to access the trace elements in the soil, like iron, that the tree needs. Next, this is a tree that needs water, in fact, constant moisture in the soil. The root system is shallow, and evaporation alone will take a great deal of the necessary moisture away. Begin by pushing a hose into the soil around the tree, and letting a slow dribble go into the soil until water appears on the surface. Repeat this about every other day, probably for the entire summer. If the water then stands on the soil for more than 30 minutes, you probably have a clay, (and possibly alkaline) soil, which only adds to your problems. Working organic material into the soil around the plant will help neutralize the non-draining problems that clay creates, but this will be difficult to do without harming the tree roots.

Ordinarily, in transplant shock, we recommend trimming or pruning some of the top growth on the plant to relieve the pressure on the roots of getting water to all parts of the tree. However, in this case, do not prune. The birch leafminer and bronze birch borer, mentioned above, are active in warm weather, and will take advantage of any wound or cut to the bark to enter this tree. If the tree survives that long, trim in late Fall, taking out any dead limbs and shaping slightly.

Finally, mulch the tree roots thoroughly, with an organic mulch like shredded tree bark. This will help keep the roots cool, hold in the moisture, and protect the tree from damage from trimmers and lawnmowers. The organic mulch will slowly decompose and add nutrients and improve texture in the soil, so keep the mulching up. For further help, especially on insect pest control, contact your county extension agent at Washington State University Extension, Pierce County.

We do hope your little tree recovers and flourishes. If it does not, however, please consider replacing it with a tree native to your area, and planting it at an appropriate time. And be sure to properly prepare the hole in advance by adding organic materials, mixed with the existing soil, to futher aid in the successful transplanting. If you are determined to have a birch, we found the following four that are native to Washington State:

Betula occidentalis (water birch) - 20 to 30 ft. tall

Betula papyrifera (paper birch) - 50 to 75 ft. tall

Betula papyrifera var. papyrifera (paper birch)

Betula pumila (bog birch) - referred to as "shrub"

Betula occidentalis