Growing Concerns 540: Scientific shade tree report, bindweed


Even an Amateur Scientist can learn a lot from looking at Trees


Help! I belong to a group that must do a science project on shade trees. Any ideas? - L.E. -


Congratulations, it's a commendable goal in a field that needs the contribution that such projects can make, which is to open the eyes and change the perspective of all parties involved. For instance, both those who do and those who view a project report on how trees respond to being planted at varying depths are likely to learn that it is a serious mistake to plant trees too high above ground, like molehills, and even worse to plant them too deep.

Use standard scientific method to look into such a topic and then illustrate what you did and learned. That is, observe a phenomenon, formulate a hypothesis to explain what you see, use that hypothesis to predict other phenomena, and then perform tests to confirm or rule out the hypothesis.

For instance, you may observe that trees of the same species often grow at different rates. Investigation will reveal that you can record these growth rates by measuring the length of twigs that grew this year, and even learn to see how much a branch grew over the past several years.

After observation on your own and research in Arboriculture books and journals you may hypothesize that slowed growth goes with a tree being planted too deeply -- with its root flare, that point where straight trunk flares into main roots, buried below grade. So you test your hunch by locating a number of trees of a given species, then collecting twigs, taking photos and measuring to record the growth rate and relative depth of planting of each tree. Then you display and report your results.

Here are some misunderstood and frequently mishandled aspects of growing a shade tree, along with some clues on where to find research data or subjects. From each can spring dozens of possible projects:

Trees with smaller diameter trunks transplant more readily and resume normal growth more quickly than transplants with larger trunks. One might record the growth rates of small trees -- "whips" -- just planted this year in a nursery field by a knowledgeable grower such as a local nursery and compare that to the growth rates of larger trees of the same species planted this year on a golf course or other favorable site.

Mulch should be applied over the roots but not against the trunk of a tree. One can compare the growth rates, and check for discolored, rotted bark at the bases of trees mulched in each way.

Trees grow faster than people think they do. Beeches, oaks, ginkgos and others are mistakenly assumed to be slow growers, and so are sometimes overlooked as potential shade trees. Researching the expected growth rate and then sampling actual growth can be an eye opener. (What's Coming Up 50 helps you determine growth rate.)

Burlap, wire cages and all cords are impediments to root growth and should be removed. Slow root growth means slower branch growth and greater incidence of trouble. Trees known to have been planted with cages, cords and burlap intact can be located easily -- the challenge will be to find comparison trees of the same species, planted properly!

Trees should not be staked unless they are planted in extremely windy sites, in shifting soils on slopes or as bare root trees. Find trees that were not staked and record the incidence of leaning or toppling. Investigate trees that were staked and record the incidence of injuries related to the staking, such as girdling by wires and chafing.

The bark of trees is a fragile but very important defense system, which can be injured in many ways. This can slow the trees growth and cause other problems. Trees bark exposed to weed whipping, mower collision, high pressure water torture by sprinklers can be examined and growth rate and health of those trees compared to trees more fortunate.

Have you battled bindweed?

I offer no new advice, today. Thoroughness, regularity and persistence are still the only way to beat this pernicious perennial weed that twines up, over and through our plants to smother them with elongated heart shaped leaves even while beguiling us with white trumpet type flowers. However, since it does little good to cry and few of us care to implement the more successful strategy of moving to a new home on a site free of bindweed, we may as well have some fun with the topic.

So, report in, bindweed warriors. If you've beaten it, tell us how long it took and what tactics you employed. If you've been fighting it for a number of years and see improvement even though you haven't won a sure victory, tell me what I should tell those just entering the fray what they're in for. I'll try to devise appropriate awards for both the person who's battled it the longest and the one who beat it the fastest. To those interested in applying for longest-running war, be advised that you have to do better than the five years currently under discussion by Cathy.


Green thumbs up

to incredibly light, warm silk long johns, available in both feminine white and masculine black at stores that sell camping gear. In terms of getting ahead and staying ahead of yard work there are no more productive times than in November and April. Edging, weeding, pruning, dividing and mulching get done most quickly, stay done longest, have the least negative impact on desirable plants and the best impact on your physical condition on those late fall and early spring days when you may feel it's just too chilly to be out there. So don some appropriate clothing and get out this weekend!


Green thumbs down

to gardening according to the rules as stated by "experts" who know so little about the area that they may believe we grow polar bears and permafrost here. If you've read we can't plant after mid- October or your plants will "heave," check the author's credentials. Be sure that the person you get information from has working knowledge from your state, not just their own, local area.


Originally published 11/1/03