Let's talk about some basic information about trees. This general knowledge can help you plan your landscape and care for the trees already in your landscape.
All trees and shrubs have a life expectancy. However, any stress on a mature tree can shorten its life. During a dry or hard winter, we could see some harmful affects being expressed such as dieback of twigs and branches in tree crowns. Cottonwoods are notorious for shedding many leaves during summer dry periods. In conifers, dry weather may cause yellowing and browning of needle tips particularly in late winter or early spring before the ground thaws out. Dry and stressed trees are more prone to pest problems such as borers.
Mature trees have expansive root systems that extend from 2-3 times the size of the leaf canopy. Major portions of actively growing roots are located outside the tree's drip line. The annual root system (absorbing roots) take up a majority of the water and essential elements in a tree. Annual roots are not the woody roots seen when a tree is dug.
Trees lose significant amounts of water directly through the leaf surface. Trees also lose some water through twigs, green branches, roots, and stems. Trees during dormancy also lose some water. Water loss from tree surfaces depend upon tissue temperature - the higher the temperature, the more water loss.
Start with a soil test before fertilizing trees, since most trees receive enough from fertilizing lawns. As trees get older, the less nitrogen is needed. If trees are stressed, such as dry weather, insects, disease, there is some research, which shows positive results from fertilizing.
The best time to fertilize is early spring when the leaves start to emerge. For mature trees this is the only time of the year necessary, but for younger trees two thirds should be applied at this time of year and the rest divided up two or three other times during the year, such as May or June and then again in September (approximately 1.5 # nitrogen/1000sq ft). Over fertilization especially of older trees can be very detrimental to the health of the trees. Many lawn fertilizers contain weed and feed formulations that may be harmful to your trees.
When you apply a broadleaf herbicide to your turf, remember, tree roots co-exist with turf roots. The same herbicide that kills broadleaf weeds in your lawn is picked up by tree roots and can harm or kill your broadleaf trees if applied incorrectly.
Pruning is the most common tree maintenance procedure next to watering. Pruning is often desirable or necessary to remove dead, diseased, or insect infested branches, and to improve tree structure, enhance vigor, or maintain safety. Since each cut has the potential to change the growth of (or cause damage to) a tree, no branch should be removed without a reason, and please do not top these trees. Always remember to prune limbs next to another branch or the trunk, and never leave a stump. By making a flush cut this allows the tree to heal around this wound. I also do not recommend putting any paint or tar or other wound dressings on these cuts.
It is recommended to add an organic mulch layer of 2-4 inches deep out at least 2 feet, of loosely packed shredded leaves, pine straw, peat moss, or composted wood chips. Do not place mulch next to the bark of trees.
Although tree removal is a last resort, there are circumstances when it is necessary. Removal is recommended when a tree is dead, dying, or considered hazardous, is causing an obstruction or is crowding and causing harm to other trees and the situation is impossible to correct through pruning, is to be replaced by a more suitable specimen or should be removed to allow for construction.
