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Wednesday - July 05, 2006

From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders, Propagation, Transplants, Trees
Title: Leaves falling off recently transplanted mature Mountain Laurel
Answered by: Joe Marcus

QUESTION:

I have recently purchased a Mountain Laurel for my backyard landscaping. It is a fully matured ML standing over 9 feet tall by 6 feet wide. Since it was planted (about 6 weeks ago) it has been losing its leaves. I live in the NW part of Austin in the hill country. The tree gets a fair amount of sun as it has only partial shade from a taller Live Oak that has an encroaching canopy. I have manually fed it Lady Bug brand John's Recipe Fertilizer, which consists of 3% Nitrogen, 1.5% Phosphate and 2% Potash obtained from fish emulsion and seaweed extract. It is automatically watered by my in-ground irrigation system every other day for 15 minutes. Are the leaves that are falling off a sign it is not doing well or could this just be the result of it being recently transplanted? What can I do to improve it's chances for success and get it healthier?

ANSWER:

Mature trees of any size resent the process of transplantation; mature Texas Mountain Laurels, Sophora secundiflora are especially unforgiving.

Plant response to transplanting (transplant shock) is a complicated issue, especially for plants like yours. Some of the factors involved may include the general health of the tree before transplanting, type of transplanting method used, size of the root ball relative to the size of the top of the tree, time of year transplanted, time of day of transplanting, weather conditions on, before and after transplanting, soil conditions before and after transplanting, pruning at time of transplanting, and after-transplanting care. This is by no means an exhaustive list, other factors can also play a role in transplantation success or failure.

It is not possible to say whether or not 15 minutes of irrigation every other day is too much or too little without knowing how much water is being applied during that time, how porous the soil is and how the water is going into the root zone.

Leaf drop after transplanting is a symptom expressed by the plant that it is not taking up enough water to support all of its foliage. It is tempting to water more in response to leaf drop. However, that is often a fatal choice for your plant. The better solution is almost always to remove foliage by pruning. In general, mature, field-dug trees should have 1/3 or more of their foliage removed at the time of transplanting. This is usually accomplished by judicious pruning of branches.