Tomorrow, the El Paso City Council will consider a proposal to lift the ban on mulberry tree plantings. The ban has been in place since 1992 because the trees produce a great deal of wind-born pollen that aggravates the allergies of many city residents.
The mulberry has many things going for it. The tree provides a dense shade that can significantly cool the area under its canopy. When planted near south- and west-facing windows, it can reduce summer cooling bills. Since the tree is deciduous, the same tree will allow heat from the sun during the cooler winter months, reducing heating bills as well. Mulberry trees are well adapted to the desert environment; they tolerate the heat quite well and require very little water.
Beside the allergen problem, the mulberry has another attribute that makes it less useful as a residential tree. Left to grow naturally, the tree can become quite large and outgrow the boundaries of all but the largest residential lot. This will become even more of a problem because most developments in the city since the ban was put in place have very small lots.
Since the trees can get so big, it is a quite common practice to prune the tree down to its trunk, a practice sometimes referred to as topping. Not only is this practice very unaesthetic, it is also quite dangerous. The pruning wounds immediately subjects the tree to disease and decay, and the new growth stimulated by the pruning is weaker and more prone to wind and storm damage.
Dr. John York, an El Paso allergist quoted in today's El Paso Times story (not a permanent link; should be good for a week), "did not recommend lifting the ban on the mulberry tree but suggested that the city also ban further juniper plantings in the city." While native junipers do indeed cause serious allergy problems, plant cultivators have solved this problem. Almost all the juniper trees available in nurseries are female cultivars that do not release pollen. Further, they gather the wind-blown pollen from their male counterparts.
Like junipers, mulberry trees also have separate sexes. If plant breeders made available a dwarf, fruiting mulberry tree, it would be highly useful in the El Paso area. Until such trees are available, I think city residents should consider alternative trees.
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2 comments:
I am a fellow El Pasoan. I like my female mulberry but the male makes both my daughter and I very sick when it is in pollen state. It is a lovely shade and climbing tree the rest of the year, though. We have enjoyed our two.
Also bought the book you recommended in the previous post. I am enjoying it in bits and pieces as I have time to read it. Thanks for the recommendation! :)
It's good to hear from another El Paso gardener. Best of luck to you.
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