Trees should be long lived if plant selection, soil preparation, planting, mulching, establishment, and maintenance are done right. Unfortunately they don’t always live long. Since trees are so much a part of our lives including our yards, neighborhoods, parks, communities, cities, towns, and forests, everyone has ideas and opinions about trees. Some of these ideas and opinions about trees have led to tree myths, so let’s review a few.
Buy the largest tree you can find. This is not always the best idea. If the tree is container grown and you find a 4-5 foot tall tree in a 10 gallon container and one of the same type that is 6-7 feet tall in a 10 gallon container, I would get the smaller tree. The larger one may be root bound with circling roots in the container that will result in a poor developing root system in the landscape. Large field dug trees take longer to establish since they may lose 90% of their root system when dug at the nursery.
Trees should always or never be fertilized at planting. Some say that you never fertilize trees with nitrogen at planting. Some say never put fertilizer in the planting hole. Some say that new trees should always be fertilized with phosphorus. First, soil test to determine what is deficient in the soil and apply what is recommended. Extra phosphorus will not help root growth if there is already plenty in the soil. Second, do not apply fertilizers with nitrogen when plants should not be actively growing. Avoid fertilization in late summer to early fall (September-October) and in late winter (January-February). Third, it is better to fertilize a large area like a mulched planting bed with many trees and shrubs than to fertilize a small confined area. If trees are planted in a fertilized lawn then there is no need to fertilize the trees separately.
You should amend the soil in tree planting holes. This one is often debated but the general consensus is do not amend individual planting holes. Large planting beds can be amended with composted organic material to improve the soil.
Do not disturb the roots of trees at planting. Container grown plants may have circling roots. These circling roots can be pruned by slicing several inches into the root ball in 6 to 8 places around it. Do not plant trees that have extreme circling roots. Field dug plants should have as much artificial non-degradable materials removed as possible once the plant is set in the hole. This means to cut at least the top half of the wire basket and burlap away. Also on field dug plants make sure the top of the root ball is where the first roots are. The stem should widen at the base and you should be able to feel the first large roots right at the surface of the root ball. If not then remove soil from the top until you do.
Compact the soil around trees when you plant them so they don’t fall over. The soil that goes back in the hole should be broken up and not compacted. Water the tree in well to remove air pockets without compacting the soil. Compacted soil slows root and overall plant growth.
All trees should be staked after planting. Trees only need to be staked if required in the specifications. Some say only to stake trees if they won’t stand up. That is true in very young bare root trees. If you are purchasing a tree to go into a landscape and it will not stand up without a stake then you don’t want that tree. Trees develop thicker and stronger trunks faster if they are allowed to sway with the wind.
More mulch around trees is better. This is not true for mulch depth. Never put mulch against the trunks of trees. Tree mulch should be placed shallow and wide around trees. Two to four inches deep but again not against the trunk and two to three times the diameter of the root ball, just like the width of the planting hole. As trees grow the mulch ring should expand in diameter as well.
Pruning is only for large trees. It is easier to prune trees when they are small versus waiting until they are large to correct problems. Most trees should have one main trunk. If you’re not pruning, you should remove competing main trunks at planting. Pruning at a young age should remove lower limbs for ease of maintenance.
Trees have deep root systems. Most tree roots are in the top 6 to 24 inches of soil. Fine feeder roots are closer to the surface and large structural roots are deeper. Soil compaction and poor drainage are usually the limiting factor for root depth. Most tree root systems are like a pancake instead of a carrot or a mirror image of the canopy. Tree roots spread at least 2 to 3 times as far as the branches spread.
Tree wounds should be painted or sealed. Paint or tree wound sealants only make us feel good. They do not stop wood rot, they seal in moisture, they prevent wound wood from forming, and they prevent trees from closing off damage.
Tree wounds heal. Trees compartmentalize wounds or decay. They plug their own vessels on the back and sides of wounds to close them off and new wood that grows begins to close them on the front side. They do not heal and go away but they are encased in old and new wood.
Topping makes trees safer. Topping is the indiscriminant cutting of tree branches back a certain distance without regard for tree anatomy or proper structure. The thought is to take weight off the top of the tree so it does not blow over. The reality is that the tree branches that regrow are weakly attached and the result is branches that begin falling out of the tree once they get 4 inches in diameter or larger. The large cuts left by topping also rarely close and result in decay at the end of the branches that are left. Topping, by removing much of the leaf growth, also reduces shading in the canopy which results in sunscald damage on thin barked species.
Lichens damage trees. First what are lichens? They are a fungus and algae that work together. They often grow on tree bark, rocks, fences, compacted soil and many other surfaces that sit still long enough. They often look scaly or feathery in appearance and may be brown, green, or gray in color. They are not feeding on plants but make their own food through the algae. We often see more of them on weakened trees simply because they are slow growing and there is often more sunlight reaching the bark on those trees.
Tree roots growing on the surface should be cut or covered over with soil. Every root a tree has is valuable to the tree for structural stability and supply of water and nutrients. Cutting tree roots can result in an unstable tree. Covering tree roots with soil can smother young feeder roots and weaken trees. You can place 2-4 inches of mulch over surface roots but keep it away from the trunk.
A tree that drops a large branch needs to be cut down. There are many reasons why trees loose branches. Wind damage may split them, shade by cause a lower branch to die, or improper pruning may have resulted in a weakened area. Some tree species like pines naturally loose lower branches to shading. As trees age they need to be evaluated for proper structure, weak areas, or storm damage. Certified arborists are best employed to evaluate the condition of large trees and recommend maintenance required.
Trees damage sidewalks, curbs, and streets. I like to say that trees just try to survive. We often plant them in bad situation where trees should not do well. Many times they struggle and die. Sometimes they overcome the situation and thrive, sending roots wherever they can to grow. As the roots and trunks grow they often come in contact with infrastructure (pipes, lines, concrete, and asphalt). If we want to keep that infrastructure intact then we need to plan for the growth of trees including designing, engineering, constructing, and planting properly so there is as little conflict between trees and infrastructure as possible.
If you are interested in learning more about trees and helping out the community, I encourage you to participate in Greenville Community Tree Day on Saturday, November 8. The event is sponsored by ReLeaf and the City of Greenville. You can learn more about ReLeaf and the Community Tree Day by visiting www.releaf.us. If you have gardening questions contact the Pitt County Master Gardeners at 252-902-1705 or firstname.lastname@example.org.