fallen coral tree (Erythrina sp.), a frequent occurrence when this tree is planted in a lawn

In the confrontation between people and nature, people tend to prevail.
There has been some controversy as to whether people should rebuild their homes in wildfire areas because of the potential danger of living there. Well, if people leave their homes because of proximity to combustible wilderness, they may as well leave the more built-up areas of Southern California as well, due to the other natural hazards – flood, mudslide, drought and earthquake – that all of us face.
Each time I drive down San Vicente Boulevard in Brentwood, I am reminded of people’s horticultural obstinacy in the face of ecological logic. The parkway median in the center of this wide thoroughfare is planted with coral trees. The coral tree (Erythrina caffra) is a magnificent, muscular-limbed species that loses its leaves in the winter and then, still in leafless condition, produces fiery orange flowers.
The only problem with the coral tree is that it simply cannot support its own weight. It must be pruned at least once a year. The best time to do this would be in March or April, following bloom so as not to sacrifice flower production, but the moment your coral tree looks top heavy, you should prune it, no matter what the season, even if that means pruning every six months. I have seen many fallen or split-apart coral trees over the years, despite their having been pruned on an annual basis.
If you look at the more mature coral trees on San Vicente Boulevard, you will notice that many of the trunks show scars where large branches have broken off. Because of their top-heaviness and brittle wood, coral trees don’t live long. Nevertheless, each time a coral tree on San Vicente Boulevard dies, it is replaced with another. Some would argue that a different, sturdier type of tree should be planted on this median. Yet so beloved are the Brentwood coral trees by the surrounding residents that it has been written into the city’s specific plan that “no major alteration of the (San Vicente Boulevard) median strip shall occur without a public hearing.”
Ironically, perhaps, the coral tree, which is native to South Africa, has been designated the official tree of the city of Los Angeles. Some would change our city’s official tree to a native species of oak, for example, but others insist that since nearly all our city’s residents (or their parents) came from somewhere else, it is only proper that the city’s official tree should also be an import.
Q: Our navel orange tree is about 25 years old and this year we are experiencing the ripened fruit splitting. Do you know what the cause may be?
Bob Triggs
Granada Hills
A: Split citrus fruit is a common phenomenon and is not a sign of disease. Split fruit is perfectly edible as long as you pick it before fungi or insects find their way inside. The usual cause of split fruit is too much water. Over-irrigation of orange trees – and of all other citrus, for that matter – is common. Even in hot weather, citrus should not be watered more than once every other week. When you do irrigate, water deeply by allowing a trickle of water to soak the root zone for 12 to 24 hours, depending on how quickly your soil drains.
Splits are occasioned by rapid growth of the fruit pulp at the expense of the peel. A sudden increase in water uptake by the tree, made possible by heavy irrigation after a dry spell or by a sudden rainstorm, could cause accelerated growth and expansion of the fruit pulp to where it splits the peel.
Q: I would like to plant a nonflowering shrub that would grow to a height of 8 to 10 feet and serve as a screen along my property line. I am going to use a soaker hose for irrigation. What would you plant and what should the spacing be?
Robert McCarthy
Tarzana
A: The most dependable hedge plant in the Valley for an 8- to 10-foot high screen is Texas privet (Ligustrum japonicum ‘Texanum’). This plant is not drought tolerant, however, so it is wise that you will have a soaker hose in place for irrigation. You can plant your privets every 3 to 5 feet along your property line, depending on how quickly you want your hedge to fill in. Texas privet does flower briefly in mildly fragrant panicles of white, but flowers are not significant and may be sheared off in the course of pruning your hedge.
TIP OF THE WEEK: The best bedding plant for planting in the shade this time of year is cyclamen. Cyclamen has silky flowers in white, pink, rose, lavender and red. Cyclamen is pricey, up to five times more expensive than primroses, which are also recommended as cool-season bedding plants for the shade. Primroses, however, are more attractive to snails and more susceptible to chlorosis than cyclamen. Cyclamen are also more long-lasting than primroses and should continue blooming until March or April.