It may well be that the date palm will soon vanish from the Los Angeles landscape, due to an insect pest and a fungus disease. The date palm gained everlasting literary fame when King David, in Psalm 92, compared it to a righteous person. According to a popular interpretation of this comparison, the thousands of fruit borne by a date palm represent the myriad disciples of the righteous. Yet, as long as there are still a few righteous and saintly souls residing in Los Angeles — and, after all, they don’t call it the city of angels for nothing — we will be just fine, date palms or not.
Four species of date palms are locally seen. The date palm grown for its edible crop (Phoenix dactylifera) is usually not planted for ornamentation on account of the fruit, which can create a significant mess when, over-ripe and unpicked, it falls and splatters. Notable examples of edible date palms in our area include those growing on Ventura Boulevard in front of National Unversity opposite CVS in Sherman Oaks, another batch in front of the apartment hotel on the corner of Milbank and Woodman Avenues in Sherman Oaks, and twenty trees in the Lowe’s parking lot in West Hills. I have tasted some of the dates that fell from these trees and found them dry and bland. The reason for this is lack of pollination. The date palms that fruit are females and if there are no male trees around, or if the pollen from the male trees is not available at the right time, insipid fruit is produced. In commerical date orchards, pollen-laden male flowers are detached and placed in female trees to ensure pollination.
The Canary Island date (Phoenix canariensis) is a stout, towering tree used in colonnades, installed in a row on either side of boulevards, driveways, or entryways to hotel resorts and other signature destinations. The Senegal date (Phoenix reclinata) is a tall, multi-trunked beauty that evokes remote, white-sand islands and shipwrecked castaways. The pygmy date (Phoenix roebelinii) is the most versatile of the group. Reaching a mature height of only eight to ten feet, it can be grown outdoors either in sun or part shade, in the ground or in pots. As an indoor plant, it requires bright ambient light, but suffers from exposure to intense direct sun.
As in so many other areas of life, these days, there is a stark division among those who love and those who revile palm trees, date or otherwise. Palms, especially those extremely tall and skinny Mexican fan or needle palms, compose the iconic skyline of the city and the thought of losing these landmark trees is inconceivable to some. Yet, in a city of often suffocating summer heat, palms provide little, if any, shade. Their shallow roots make it difficult for anything to grow around them and their fruit and seeds can be a major nuisance.
Thus, some people are saying “good riddance” to a population of 75,000 local palm trees that are threatened by a black beetle and a fungus. The beetle, known as South American palm weevil, which grows two inches long and, like all weevils, is distinguished by an elongated snout, has not yet arrived in Los Angeles, but has been killing palms in San Diego for the last six years on its way north.
Adult palm weevils land at the base of a palm frond and lay eggs there. As the beetle grubs hatch, they burrow into the trunk of the tree, hollowing it out. A danger of beetle infested trees is that the crown at the top, having lost its core, may suddenly break off and crash to the ground, endangering property and people below.
Fusarium fungus, on the other hand, is native to California soil and is particularly dangerous to the health of aging Canary Island date palms (Phoenix canariensis). As indicated on the website at selectree.calpoly.edu, the average lifespan of a canary palm is 50-150 years. Since the canary palms at Elysian Park, for example, were planted 120 years ago, it stands to reason that they would begin to die. Like all living organisms, palm trees become more susceptible to disease as they age and, as far as canary palms in Los Angeles are concerned, the disease agent leading to their demise is typically Fusarium fungus.
With the exception of the famous Hollywood fan palms and the Elysian Park Canary Island date palms, there are no plans to replace municipal palms that die with other palm trees. At Elysian Park, dying canary palms have been interplanted with one hundred Chilean wine palms (Jubaea chilensis), which are apparently resistant to the Fusarium fungus. Chilean wine palms are named for the fact that they were once cut down for their sap, which may be fermented into wine. Wine palms are the most cold tolerant feather palms, capable of growing as far north as Santa Clarita and surviving temperatures down to 10 degrees Fahrenheit. The most cold tolerant fan palm, incidentally, is the windmill palm (Trachycarpus fortunei), which I have seen growing in the Antelope Valley, albeit under tall trees that gave it an extra measure of warmth on cold nights.
If you have a palm tree of any description, the best way to keep it from getting a disease is never to prune it except for the purpose of removing dead fronds. According to Don Hodel, Cooperative Extension Environmental Horticulturist for Los Angeles County, “Unpruned trees never have Fusarium . Prevention through sanitation and more conservative leaf pruning and trunk skinning is the only way to control these diseases.” Trunk skinning is the practice of removing pendant but living fronds from a palm, especially a canary palm, where the end result is a so-called pineapple or symmetrical bulge at the top of the crown. Creating a pineapple is an open invitation to infection by Fusarium spores. Some say that you only need to disinfect your pruning saw between cuts and you can avoid disease but this is not always the case. Even if your tools are sterile, spores floating in the air can land on cut, green, living surfaces and enter the tree from there. To be safe, forego the pineapple look and accept that drooping fronds will only be removed when they are completely brown or dead.
Tip of the Week: For an attractive indoor or patio plant, grow a date palm from seed. The seedling that sprouts will grow slowly and will require increasing doses of sunlight as it develops. After eating a date, you can usually sprout its seed easily enough.. Seeds from fresh dates are easier to sprout than those from dried ones, but both types are likely to germinate. Soak the seeds in water for 72 hours, changing the water once a day. Then dunk some peat moss in water to the point of saturation, mingle your date seeds within its fibers, and place moss and seeds inside a sealed plastic bag at room temperature. Within two to four weeks, most of the seeds will have sprouted, at which point they can be removed from the bag and planted in regular potting soil. Simply soaking the seeds in water prior to planting, without the peat most and plastic bag treatment, will also lead to positive results, except that germination will be slower.