Just as its name declares, this perennial brings a little bit of white brilliance to the summer garden. It thrives well in shade and in part sun, thereby spreading and filling in a lot of space. The name doesn’t tell the entire story because this plant is also admired for its delicate silvery leaves. It makes an excellent ground cover for dry areas. The leaves spread a mat of foliage from which the flower stems rise. It also will cascade over rocks and walls.
Nothing adds the same quality and value to a landscape as a healthy mature tree. The benefits include cooler outdoor spaces, cooler homes, aesthetic appeal, carbon capture, stormwater mitigation and more. There are some key things to think about when it comes to keeping your big old tree happy.
What are the key parts of the tree and what do they do? All the parts are important, many are redundant, and how they play together really matters. The redundant parts are leaves, small branches and small roots underground. While critical for tree health, the tree can lose some of any of these without suffering fatal damage; the tree will, with time and to the best of its ability, replace those lost parts with new growth.
The fine roots explore for water and minerals in the soil, hopefully with the help of symbiotic soil fungi. Only the youngest, smallest roots (those that haven’t even grown bark yet) take in water, like tiny sponges. These roots grow when and where soil moisture is available and die off when the soil gets too dry. Trees may have several flushes of absorbing roots growing and dying back over a season. Once in the roots, water moves up successively larger roots as it travels toward the stem.
There is one part of the tree that is not redundant. This is the root crown, or root flare, where the ropy wood of the root system changes into the blocky wood of the stem. The happiest, healthiest trees have a strong root flare visible above the soil line. These root shoulders act like buttress supports for the huge load of wood and foliage being acted on by gravity and wind.
As water moves up the trunk, it travels in sapwood (or xylem) — living wood just underneath the bark layers. Outside the sapwood is a thin ring called the cambium, cells that make new cells that make new cells … for as long as the tree lives. Outside that layer is the inner bark (or phloem), a green spongy layer with many functions, including moving sugars and other metabolites from the leaves to wherever they need to go. These three layers — xylem, cambium and phloem — constitute the “living rind” of the tree and are protected by the dead but intact outer bark layers. The central wood, or heartwood, is dead but intact as well.
Leaves out at the end of the small branches are busy converting sunlight energy into stored chemical energy in the form of sugars. These are then used as fuel and as building blocks for the tree to power its ongoing life functions and make the complex chemicals needed to do so.
What harms a tree? Things that harm the root system (soil compaction, drought, heat, chemicals), things that damage the root flare (stem girdling roots, mowers, construction), things that damage the living rind (wire girdling, kids with hatchets, vehicles) and things that damage leaves (over pruning, certain herbicides, heat). There are feedback loops, especially between the roots and the leaves. Root damage that reduces water uptake leads to leaves making less sugar which means less resource to grow new roots. Herbicide damage that deforms leaves leads to less sugar feeding root function as well as less pull on the water, both leading to less water and nutrient uptake going back to the leaves.
So, here’s what you do: Avoid those harmful things!
Protect roots by covering the soil with 3 or 4 inches of arborists’ wood chips. This cools soil, reduces soil water loss, cools air above, breaks down and feeds minerals into the soil, and promotes growth of beneficial soil fungi. Avoid cutting roots when possible; when necessary, cut as few as possible and cut as far from the trunk as possible. Don’t compact soil by dumping gravel all over it or parking on it. Don’t apply herbicides to the root zone, which is larger than the canopy above.
Protect the leaves by avoiding over pruning. Most mature trees don’t need regular pruning, and, in fact, that should be avoided. Pruning takes away energy sources (leaves) and creates energy sinks (wounds that must be dealt with). Excessive pruning can send a tree into a starvation spiral. Prune for specific goals. Avoid herbicides like those found in weed-n-feed fertilizers.
Protect the living rind by taking away Junior’s hatchet. More seriously, don’t tie wires or ropes around the trunk and branches unless you check them every year to make sure they aren’t girdling the tree. Lastly, don’t run into them with your car!
A tree-protection cage which has become a tree strangling cage. Severely stunted growth on an ash tree; imazapyr herbicide damage is likely cause.Construction damage, while often unavoidable, will lead to health decline in mature trees.
Author: Joran Viers is an arborist at Legacy Tree Company. Contact him at joranviers@legacytreecompany.com Have a question about the article? AskAnExpert@abcwua.org
If you’ve walked around your neighborhood, you’ve probably noticed cherry trees being flocked by birds and buckets of fruit with “Free Organic Apricots” signs. Yes, it’s harvest season in Albuquerque. Have you ever wondered what becomes of all that fruit?
Back in 2014, avid canners and food preservers Erin and Trista noticed fruit trees around Albuquerque going unpicked. They placed an ad on Craigslist, asking for access to unused trees. The response was overwhelming, and this local chapter of the Food is Free Project, a global movement started in Austin, Texas, began.
Food is Free Albuquerque (FIFABQ) harnesses the abundance of fresh food within our community and connects it to people in need. The nonprofit considers fresh food a human right and aims to reduce food waste while fighting for food equity and access to fresh and nutritious food.
Volunteers help to harvest fresh food throughout Greater Albuquerque and Santa Fe. They then distribute the fresh food throughout the community in which it was gleaned to keep food as local as possible. Last year, 26,315 pounds were harvested.
FIFABQ fosters social empowerment through the growing and sharing of fresh food, striving to tap into the abundant private food resources within our community and redirecting millions of pounds to those overlooked by the existing food system. FIFABQ harvests everything aside from crab apples, mulberries and prickly pears.
The produce is predominantly distributed through collaborations with various organizations committed to feeding the community citywide. Explore the list of their partner organizations on the website.
Have you ever heard of forensic arboriculture? Probably not … but it is a thing! Figuring out why trees die can be a challenge as there are often multiple causes, and the clues may be obscured by time or a deep layer of rock mulch. If you look at enough dead and dying trees, though, patterns begin to emerge.
In our desert environment, one major overarching cause of tree death is thirst. Most of the trees we plant are not native, at least not to the desert grasslands that make up the native ecosystem throughout most of our region. Since these trees are native to regions with higher natural rainfall, we must make up the difference through irrigation.
Some trees die of thirst simply because there is not enough water in their root zones to supply the trees’ needs. Drought symptoms might include smaller leaves and less-dense canopies, dead twigs in the outer canopy, and droopy foliage. Because it takes a few years for trees to really show stress, it will take a few more years for them to show a strong response to improved conditions — but they will!
They will … assuming there aren’t other issues. One of the more common causes of drought stress, and possibly death, in trees is the presence of stem girdling roots. These are roots, usually from that same tree, that grow in a tight noose around the lower stem, just below ground level. Roots grow that way when they spend too long in a nursery pot or when they are only irrigated right at the very base of the tree. However these girdling roots start, they often end up causing a “choke point” where the trees’ vascular tissues are gradually crushed and the flow of energy-rich sap to the roots is reduced, as is the flow of life-sustaining water up to the leaves.
Stem girdling roots can be removed at planting, or even later if they are found. A sharp wood chisel often does the trick. Making sure trees are not planted too deeply is a great way to avoid creating stem girdling root problems. Many landscape trees are planted too deeply, which is rarely fatal on its own but can stunt growth, as well as setting up stem girdling roots.
Other kinds of girdling can kill a tree. All too often, mostly in public and large commercial landscapes, we find young, recently planted trees with large wounds just above soil level. These are wounds that have taken off the bark, leaving bare wood exposed to the elements. Any time a tree is wounded this way, it’s “living rind” of inner bark, cambium and sapwood are greatly compromised. The wound also exposes the inner wood to decay, so that if the tree doesn’t die quickly due to the destruction of the living rind, it runs the risk of breaking at the base when the decay cavity gets too big. By then, the tree may have some size and so present a real risk to people and their important things — cars, houses and such.
Another avoidable cause of tree death is poisoning with herbicides. In this time of instant gratification and “convenience is king” thinking, people often react to the presence of a few unwanted plants by applying a lot of chemicals to kill those plants. Often, tree roots grow in the treated areas and take in sublethal to lethal doses of herbicides. This happens in public spaces, commercial spaces, residential spaces … we could all be a lot more careful with our chemical use!
Herbicide damage usually reveals itself as weirdly deformed, often very stunted, leaf growth. These distorted leaves cannot capture enough carbon through photosynthesis to keep the tree healthy, so decline follows, with death nipping at its buds. Trees may recover from a one-time application, but repeated applications across seasons and years may well lead to death.
Large stem-girdling root on a young Chinese pistache which was dying and had to be removed.
Keep your trees alive and healthy with these simple steps. First, make sure the tree doesn’t have a stem girdling root problem. This requires carefully digging around the base until you find the main root flare, and cutting away roots that are circling tightly around the stem. Then, make sure nothing else damages that lower trunk area, keeping that outer bark intact and protecting the living rind below. Finally, make sure your irrigation system is adequate. Established trees need water broadly out under the canopy, and even beyond, but not so much at the very base.
Large stem girdling root at the base of a honey locust tree. Prompt removal of the root is recommended. Mower or string trimmer damage to a young tree. This will lead to decay and disease entering the very base of the stem.
Author: Joran Viers is an arborist at Legacy Tree Company. Contact him at joranviers@legacytreecompany.com Have a question about the article? AskAnExpert@abcwua.org
This beautiful deciduous native shrub fills with unique purple spiked flowers in May and June. This plant is adored by wildlife for its small seedpods, and pollinators love the flowers. It also serves as a host plant for some butterfly larvae. The False Indigo has small dark green deciduous leaves that are attractive in the garden. It is a workhorse when used in abandoned fields or along streambeds as it enriches heavy clay soils and stabilizes slopes.
