Dallas Morning News - October 20, 2016
Q. I am sending you a couple of pics from my neighbor's elm tree. It is a native tree on a hillside and has a nice flare. There are other elms on her property that are starting to show the same signs. Do you have any idea what the problem might be? R. C. San Antonio, TX
Q. You talk and write an awful lot about planting trees high and exposing the flares of trees that didn't get planted high enough. Why is having the flares exposed such an important thing? C.P. Dallas
A. Root flares of trees and other woody plants are actually part of the trunks, not the roots. That's why I often use the term trunk flare, although both are appropriate. When bark tissue of tree flares is covered with soil, mulch or groundcovers, it doesn't breathe properly and the result is a slow down of tree growth. Exposed flares breathe properly and stay appropriately dry like the rest of the trunk. Flares that are buried too long eventually start to rot and various pathogens and other pests start to move in. Flares can be exposed by homeowners with tools and water if extreme care is given to avoiding nicking and damaging the flares. I use stiff bushes like horse brushes, especially for small trees, but the best route is to have an arborist expose the flares for you with tools such as the Air Spade or Air Knife. Trees respond dramatically the first season after the work is done. You should also know that this technique is important for young and old trees. Trees can live for decades too deep in the ground while performing at a fraction of their potential. I have been involved in the flare exposure of trees hundreds of years old and the results have been spectacular. Color improves, growth increases, flowers increase and fruit trees have better productions.
Q. I transplanted a Mexican milkweed and it really likes its new location. It is huge - 7 feet across at the top, and it is attracting the bees and the butterflies. I would like to plant another. The one I have is surrounded by an ant hill. How can I get rid of the ant hill without hurting my milkweed? K. B. Denton, TX
A. Dust the ants with natural diatomaceous earth, cinnamon, hot pepper, ground up tansy or citrus pulp.
Q. My orange tree has beautiful green oranges on it. I noticed two were slightly yellow and split. What causes this? I don't want to loose what I have. Thanks. S. W. Dallas, TX
A. Cracking of fruit is usually caused by uneven moisture levels in the soil. Cool, moist weather following dry periods can cause cracking for example. Just be more careful with the watering program. You want moist soil rather than soil that is sopping wet or bone dry.
Q. Now that the weather has cooled down, how often should my automatic sprinkler be set to run? Right now it's running 15 minutes every other day. P.K. Highland Park
A. First of all, that's actually a bad schedule for hot weather. No matter what the weather is like, it's much better to water for longer periods of time and then wait as long before the next watering as possible. Short waterings keeps the moisture in the top few inches of soil, creates shallow root growth and evaporates faster. Deep watering develops deeper, healthier root growth and lasts longer. You'll also use less water long term. The best setting for the irrigation system is "off". It should be left on manual so it only waters when you push the button to have it cycle through the zones. The length of time for each setting and the schedule has to be determined by you and your staff but spray heads should be set in the beginning to at least 20 minutes and rotary heads at least 40 minutes. Every site varies due to sun/shade, soil types, slope, etc. If it sounds like more work, it probably is but it's better in every way. And, in cool weather you shouldn't be watering very often - especially if you are using the organic program.
Q. I finally have to admit that you've been right about not being able to grow grass in shade. After trying heavy pruning and various fertilizers, I must agree that switching to shade-tolerant groundcovers is the way to go if I don't want to remove any trees - which I don't. What are the easiest groundcovers to establish and how should they be planted?
A. Welcome to the most common situation we have to deal with. There are several good choices but they will all fare much better if good bed preparation is done prior to planting. It's the usual bed prep we always recommend but there are some caveats. Only about half the volume of compost, rock minerals and sugars need to be used for one. The other is the tilling issue. Forking or tilling the amendments into the soil is important for the groundcover - but it does damage the feeder roots of the trees. Trees are tough and usually bounce back but the trick to avoid the damage is to hire a contractor to mix the amendments in with the Air Spade - same tool we use to uncover trees that are too deep in the soil. It will cost more but definitely be worth considering. The groundcovers you should consider include horseherb, English ivy, Persian ivy, Asian jasmine and ophiopogon, aka mondograss. I have personally used Persian ivy but it must have total shade and be fertilized with organic products. All the others are easier to grow as well as easier to find in the nurseries.
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