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Spindly growth

Posted: Fri Oct 12, 2012 8:12 am
by PA_Docent
Almost all of the apple trees with this issue have been in the ground two years now. I am going to get my soil tested by the Univ. of Penn Extension service; however maybe someone has a suggestion or dealt with a similar problem.

All of my apple trees are situated ideally with a southerly exposure and sunshine all day. The area of the affected trees seems to be sandy, even though I think most of my other trees are in clay soil. Approximately 15-20 feet away on the north side of the affected trees is a line of mature oak, hickory and maple trees. I will be getting these trees cut down this year. Otherwise I have an ideal location/climate for apple trees.

My problem is with my two year old trees. Last years central leader growth did not put out any new limbs last year or this year; however last years growth has tightly closed buds along the central leader. I plan to cut above some of these buds early next spring trying to force limbs to grow.

When the central leader started growing again this year, the new growth put out limbs. Most of my apple trees look top heavy. Why did last years central leader growth not put out any limbs?

I will update with a picture this weekend of an apple tree and post the results of my soil test when the results are available.

I want to express my appreciation to Scott and Richard for stopping by yesterday (10/11/2012) and taking a look at my trees and informing me of my issues.

Re: Spindly growth

Posted: Fri Oct 12, 2012 11:19 am
by dmtaylor
I recently heard a rumor that hickory trees (as well as other nut trees?) produce chemicals that inhibit the growth of anything else nearby. I would validate this, and if true, yank out your hickory, roots and all, if that is the issue.

Re: Spindly growth

Posted: Fri Oct 12, 2012 5:12 pm
by PA_Docent
Thanks dmtaylor. I will get the Hickories taken care of as soon as possible. I know nothing will grow under/near black walnuts. I will check with the PA Extension Service on Monday about this.

Planting near Hickories may be true. I planted a clematis at the base of the tree hoping it would grow up the trunk of the Hickory. It did not budge in two years. I transplanted this June and it grew several inches in its new location.

Re: Spindly growth

Posted: Sat Oct 27, 2012 7:12 am
by PA_Docent
I received dome interesting information from Neil B. Collins of Tree of Antiquity (where I purchased some of my trees):

The terminal bud makes an inhibitory hormone called auxin, which moves by gravity down the shoot and prevents the lateral buds just beneath the terminal bud from growing. The effect of this hormone is to allow the stem to grow straight up without branching. In nature, this is an adaptation which helps the tree reach the light when growing in a dense canopy. Pinching (removal of the growing point or apical meristem, the source of auxin) is a well-known method of inducing branching in an otherwise unbranched shoot. After pinching, the auxin level is greatly reduced, which promotes branching by allowing lateral buds to grow into shoots. If a shoot is bent and tied down to the horizontal, auxin moves downward, to the lower side of the stem and inhibits buds there; however the top side of the stem is released from the auxin inhibition, allowing bud growth all along the stem, producing vertical water sprouts. A branch growing or bent to a 45 degree angle will exhibit partial apical dominance, with just a few lateral buds becoming shoots. Therefore, apical dominance can be controlled by either pruning off the terminal bud, or by adjusting the angle of the branch. Different species have different degrees of apical dominance, with the sweet cherry and Japanese plum having the greatest amount. Such species continually make upright, largely unbranched growth. If a spindly, weak branch is cut off half way, primary growth of that branch will be stopped (apical meristem removed), but later on secondary growth will thicken that branch stub and make it stiffer. Buds on that stub will start to grow eventually, establishing new primary growth, but that original stub will continue to thicken over time. Etiolating occurs when plants receive inadequate light and begin stretching in order to reach a source of light. This evolved to help plants move into adequate light. Plants that are not fertilized as emerging leaves appear are often malnourished. The soil test should help to answer this concern. Additionally, fertilizers that are not balanced (for instance, have too much nitrogen) can produce spindly plants.