One of the activities we need to do with regularity is to actually look at our trees. The trees can tell us different things in different seasons. In the spring, after the canopies have flushed out is the perfect time to photograph the trees. Think of this as their annual health examine. Stand somewhere that will be east to remember so next year’s photo can be taken from the same position. Not only do these annual records point out emerging problems, but they serve as valuable documentation for the health, condition and value of the tree. This can be especially important in establishing the value of lost trees.
Also watch for mushrooms sprouting at the base of the trees or in the surrounding lawn. Photograph the mushrooms to show your arborist the next time to have you trees checked. While some mushrooms are insignificant, some provide a positive id for the presence of certain pathologic soil diseases.
In the summer watch evergreen trees and shrubs for signs of drought stress. Drought stressed trees and shrubs lose their glossiness on the leaf surfaces and appear droopy and off color. In the fall, be sure to note any extra early changes of canopy color or early dropping of leaves as these can both be symptoms as well. Use the wintertime to really examine your trees branches after the leaves have fallen. With binoculars, check for cracks and hollows in the limbs. If you see Woodpeckers, have the tree climbed and examined by a professional.
Late fall is the best time to plant in our area because the ground does not freeze and it gives the trees the most time to establish before the stressful heat of summer. You can plant a container grown tree most of the year if you will water diligently. Field dug trees should be planted immediately or have their root balls wrapped and “cured” until small roots grow through the burlap. Bare rooted trees should only be planted in the coldest part of winter and should be mudded in at planting. All trees should have any kinked or girdled roots pruned off before planting. This is the only opportunity to correct the problems of root structure resulting from container production. Removing girdled roots will greatly affect the longevity of the tree.
Transplanted bare rooted trees will require the higher end of the water schedule for new trees. Give new trees 6 – 8 gallons of water per inch of trunk caliper per week, in divided doses. In other words, a 4 inch container grown tree would need a minimum of 24 gallons of water per week. It’s especially important to keep the root ball well watered in trees planted from containers. A good way to water new trees and all Palms is to place “bubblers” over the root ball. Avoid using rotors from the lawn or pop-up irrigation heads so that the trunk and root flares of the trees stay dry. You never want to see moss growing on the trunk of the tree, as this would indicate the bark was continuously exposed to water.
Do not prune back the canopy of trees at the time of planting. Leave lower branches on trees as they feed growth hormones into the trunk. Removal of small limbs will slow trunk diameter growth. If the trees require staking, remove after 1 year. Planting depth is very critical to the trees’ establishment and long term survival, as planting too deeply and/or over mulching both result in oxygen deprivation and root die back. The other most important factor for new tree survival is consistent irrigation. If you plant large caliper trees or trees with lots of leaf surface, such as Maple or Sycamore, you may want to use deep watering tubes for the first 2 summers. Put gravel in the bottom of the tubes to disburse the deep water. This way you will not create air pockets around the root ball which can dry out new roots
Irrigation should be adjusted throughout the year. Generally, it’s a good idea to set you system to run 1 cycle a week when you are typically at home. This allows you to notice broken heads or double spray areas and correct them. In the spring check your irrigation batteries. Look for signs of heat wear. NiCad batteries take the heat better in most controllers. Also, check the rain sensors when you clean the rain gutters.
As temperatures rise, adjust your irrigation up by increments over several weeks. Soil oxygenation is restored as soil air spaces open up through transpiration; therefore do not irrigate any zones more than 3 times per week.
In the summer, be sure to water around slab foundations. Observe your irrigation at a peak use time in the summer to see if changes in water pressure are affecting irrigation coverage. Water fruit and pine trees especially well in the summer. Continue summer watering throughout October, or until fall rains. Gradually decrease irrigation as temperatures drop and lawns slow down. Drop down to a maximum of 2 cycles per week in the fall. In the winter, reduce zones with lawn and trees so they receive about 1 and a half inches of water per week. One deep watering a week would be fine.
Trees use the fertilizer given to them for whatever activity they are involved in at that time. In the spring feeding produces a lush canopy. Fall feeding generally benefits root growth, so fall is a good time to apply root stimulants. Whenever trees are fed, they should be given a low salt, tree specific fertilizer. The best method of applying the fertilizer is by deep root soil injection.
The importance of water to the uptake of fertilizer cannot be over stated. Water your trees well before and after fertilization. In the spring, feed the fruit and nut trees with fertilizers containing their specifically required micro-nutrients. In the summer, feed Palm trees monthly with a fertilizer containing Manganese. Discontinue soil injection feedings when temps hit 90 degrees and during periods of drought. You can feed evergreens during the winter if you need to spread maintenance cost throughout the year.
In the spring, do structural pruning on young trees so their small wounds will heal quickly. Shorten but do not remove low branches on trees smaller than 6-7 inches diameter. In the summer, manage branches over structures with tip pruning. This is also a good time to do rehabilitative pruning designed to open up the canopy. Remove any damaged branches before storm season in July.
Fall is the best time to prune most trees. Species that are prone to wood boring insects, such as Oaks, Elms and Pines should have their wounds sealed with an aerosol pruning paint. Remove mistletoe from trees to prevent birds spreading the seed.
Winter is the best time to work on tree roots. Trim small superior roots girdling structural roots. Root pruning for the installation of root barriers and to slow tree growth is best done at this time of year. This is also the best time of year to excavate and inspect root zones or undertake disruptive activity, such as construction, which may impact the critical root zone of the tree.
Most trees and shrubs will not require more than 1 or 2 applications of mulch per year. Use of composted mulches requires a little more frequent application but is well worth it for avoiding the problems associated with non-composted mulches. In composted mulches, weed seeds and soil diseases from sick trees are eliminated through the heating process of composting. In addition, composted mulch provides nutrition immediately, whereas hardwood mulch uses nitrogen from the root zones to finish decomposing. Trees require only an inch or 2 of mulch at the most. In nature, forest floor soils contain only 2 – 5 % organic matter, so consider what a different environment we provide our trees by mulching with 100% organic matter.
The correct method of applying mulch is frequently misunderstood. Proper mulching places the peak elevation of the berm out at least 14 – 18“ away from the trunk. The interface between the original root ball and the soil immediately surrounding it is the area you wish to keep cool and moist with mulch. The goal of mulching is to entice new roots out into the surrounding soil.
Mulch piled up around the base of the tree does not allow the bark on the root flares to harden as when it is normally exposed to light and air. This soft bark loses its protective ability and allows insects and soil disease to penetrate the tree. Some trees, such as desert trees or trees recovering from chronic over-irrigation are best with no mulch at all. It may also be best to remove mulch when we are suffering a drought as mulch does not allow dew to reach the root zone.
There are many types of tree care which are best accomplished in specific seasons. In the next article, I’ll write about when you need to spray and, when to deal with specific insects. I will also give you a couple of rules of thumb for using several common horticultural products and talk about the importance of timing your treatments to the lifecycle of the insect.
Kris Bitner, TMCNP
ISA Certified Arborist 24549
Certified Municipal Specialist TX-1257AM