It’s Hurricane Season – Are your trees in shape?

By Pam Brown, Urban Horticulture Agent, University of Florida/IFAS Pinellas County Extension

As hurricane season arrives, there are many tree companies that are out and about offering to prune large trees and palms. Much of the pruning that is done can actually create a situation that puts the tree in more danger of failing in high winds than of providing protection. There has been a lot of research done at the University of Florida on the proper way to prune trees and the way that trees behave in high winds.

First, allow me to provide a bit of biology 101 refresher. The green leaves on trees and the green fronds on palms are the source of the food, through the process of photosynthesis, that these plants need to thrive and grow. When you remove green leaves and fronds, you reduce the ability of the plant to produce the food necessary to support the roots and top growth adequately. Fertilizer contains nutrients that are necessary for making proteins and enzymes but it is not the source of the food necessary to sustain the tree.

Let’s look at palms since they are so often badly pruned. When green fronds are removed, the palm is weakened. And, when all but a few of the fronds are removed in what is commonly called hurricane pruning, the trees is in more danger of failing in the wind. Those lower, fronds are mature, hardened fronds that protect the newer, more fragile fronds near the growing point of the palm. Without the mature fronds for protection, the top of the palm is more likely to sustain wind damage during hurricanes or other high winds. In addition, when this type of pruning is continued over time, the palm is weakened and may develop nutrient deficiencies and eventually decline and die. Palms are pruned primarily for people reasons and not the health of the palm. It is perfectly acceptable to remove dead fronds and blooms or fruit. And, I find that when a frond is hanging too low over the sidewalk, just cutting off the tip end of the frond will make it light enough to spring up out of the way of pedestrians. Removing the frond bases that remain attached to the trunk with a chainsaw creates wounds where insects or disease can possibly enter.

Our large shade trees are also being damaged by improper pruning. According to Dr. Ed Gilman of the University of Florida, this common malpractice on large trees of removing many or all interior low branches is considered over-thinning or “lions-tailing”. He states that “When people prune trees in this abusive manner, excessive live tissue is removed from the tree and no structural pruning is performed. This creates poor form and numerous wounds, and the tree becomes more prone to failure especially if there are few trees nearby. Old trees can decline as a result of removing too much live tissue. Only a small amount of live tissue may be too much to remove on a mature or over-mature tree. There should be a very good reason, such as to reduce likelihood of branch failure, when removing more than ten percent of the live foliage on mature trees.” Also, please do not allow anyone to top your trees for any reason.

Reducing the amount of foliage on the ends of the branches, and thus the weight, is a better way to reduce risk of branch failure during high winds. The canopy can be opened up without removing all of the interior branches and attached foliage. An arborist certified by the International Society for Arboriculture is trained in the proper way to prune and protect trees. However, all certified arborists are not equal. When requesting a quote from an arborist, ask to see their certification card, proof of liability insurance (ask for this no matter who you hire), references, and also ask if they will be with their crew when the work is done. I would suggest three quotes and then maybe even go to look at some trees that they have pruned.

You can find certified arborists in our area on the Internet at: http://www.treesaregood.org/findtreeservices/TCSHome.aspx. Or, you may call our Lawn & Garden help line (582-2110) Tuesday – Thursday and request a copy of the current list.

The following links lead to the extensive University of Florida information on tree pruning on the Internet:

http://hort.ifas.ufl.edu/woody/pruningpalms.html, http://hort.ifas.ufl.edu/woody/pruning.html

http://treesandhurricanes.ifas.ufl.edu/

In addition, you can view a 50 minute video called “Trees and Storms” on the Internet at: http://pinellas.ifas.ufl.edu/lawn_garden/index.shtml. Go to the right side of the page under "Hot Topics" and click on “Trees and Storms”.

Trees add considerably to the value of our property and keeping them healthy while providing protection from damage to our homes is a delicate balance that requires planning and caution. I hope that you will do your homework before allowing just anyone with a truck access to your trees.

Timely Tips for March – Part 2

By Andy Wilson, Pinellas County Extension, Horticulturist

This winter has brought us many warmer than average days as well as one night of below freezing temperatures that damaged some kinds of plants. March marks the end of the danger of any plant-damaging cold and many plants will be producing lots of new growth now. Here are some lawn and garden tips for March.

Aphids- As plants begin to produce new growth over the next several weeks, aphids may become a problem. These sap feeding insects feed on the soft, succulent new growth and are usually found in masses. They are pinhead-sized and may be green, black, orange or other colors depending on the particular species of aphid. If aphids are noticed, look also for predatory insects that may be feeding on them, the most common of which are the lady beetles or “lady bugs.” If these beneficial insects are found, there should be no need to spray for the aphids. If spraying is needed, light horticultural oils and insecticidal soaps are among the least toxic materials.

Vegetables- Vegetables gardens need a regular supply of nutrients to produce well. Most commonly this is done by applying granular fertilizers like an 8-8-8 analysis. Usually at least 2 or 3 applications (in addition to the fertilization that is done at planting) will be needed during the growing season. For more information see the Florida Vegetable Gardening Guide here: http://edis.ifas.ufl.edu/VH021

Bananas- Bananas should be fertilized about every other month with a fertilizer that contains twice as much potassium (the third number in the fertilizer analysis) as it does nitrogen (the first number). Bananas are heavy feeders in general and usually should be fertilized every other month. Many banana plants in the area suffered damage in the early January cold wave and adequate fertilizer will supply nutrients that are needed to produce new growth and eventually fruit. More information on growing bananas can be found here: http://edis.ifas.ufl.edu/MG040

Lawn Fertilization- The ideal time to make the first application of fertilizer on lawns is about 2 weeks after the lawn begins to show signs of fast growth after the slow growth of the winter. The grass roots are then ready to efficiently pick up the fertilizer. A 15-0-15 or 15-2-15 is suggested. At least some of the nitrogen in the fertilizer should be in a slow release (water insoluble) form. This information will be shown on the fertilizer bag.

Azaleas- Azaleas can be pruned, if needed, once flowering has finished. If the mulch around them has mostly rotted away, apply more so that the mulch is about 2 to 3 inches thick. Although there are exceptions, azaleas as a group are not the most drought tolerant plants and mulching will help to hold moisture in the soil.

Palms- One of the most important parts of the care needed to keep palms healthy and attractive is proper fertilization. Research done by the University of Florida has established that an 8-2-12-4 analysis fertilizer is best for palms. The nitrogen, potassium and magnesium should be in a controlled release form. It should also contain the micronutrients iron (about 1.5-2%, 0.1-0.2% if in the chelated form), manganese (about 1.5-2%) and trace amounts of zinc, copper and boron. Some nurseries and other outlets in the area are carrying this fertilizer. The fertilizer should be broadcast evenly throughout the area under the canopy of the palm. Applying the fertilizer in this way is much more effective than using fertilizer spikes or punching holes in which to apply the fertilizer. If there is turf within 50 feet of palms it should be fertilized with the same palm fertilizer, not a high nitrogen turf fertilizer. High nitrogen, low potassium fertilizers can induce severe and sometimes fatal potassium and magnesium deficiencies if they are applied anywhere near palms.

More information on fertilization of palms can be found here: http://edis.ifas.ufl.edu/EP261

More information on nutrient deficiencies of palms can be found here: http://pinellas.ifas.ufl.edu/home_garden/pdf/ENH1018.pdf