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Parkway Trees

Parkway Trees

The Hancock Park Homeowners Association ’48 is working to re-forest our parkway tress. We will be happy to assist you in obtaining, replanting and maintaining your parkway trees. We will also be happy to provide you with information on what type of tree to replant and how to care for the young tree. We are currently working to plant new parkway trees throughout Hancock Park. If you are interested in having a parkway tree planted please contact our Tree Committee Chairs:

Susan Grossman: segrossman@sbcglobal.net
Pam Newhouse: panewhouse@gmail.com
Cindy Chvatal-Keane: snorekel@aol.com

Certified Arborist:   Sabine Hoppner:  wateredge@sbcglobal.net, 213-713-7157

Newly planted trees require special care; and never remove or plant a parkway tree without a city permit. We will also help you obtain a tree planting or tree removal permit.

The Polyphagous Shot Hole Borer (PSHB) is a serious new tree pest in Southern California. This boring beetle, from the group of beetles known as ambrosia beetles, drills into trees and brings with it a pathogenic fungus (Fusarium euwallacea), as well as other fungal species that may to help establish the colonies. The PSHB attacks many species of trees, but some trees are resistant to the fungus it carries. The beetle is dark brown to black and tiny, with females between 0.07 and 0.1 inches long, and males even smaller, usually about 0.05 inches long. Pregnant females bore through the tree’s bark, creating galleries under the bark. They plant the fungus in these galleries, where it grows and spreads throughout a susceptible tree. The female then lays her eggs in these galleries and when the eggs hatch, the larvae eat the fungus.  The larvae develop into adults in about a month. Many more of the larvae develop into females than males, and the females mate with the males (their brothers) while still in the gallery. The pregnant females then pick up some of the fungus in their mouths, and leave through the entry holes created by their mothers to start the process again.

What happens?

There are several potential outcomes of a beetle attack.

1.      Beetle is repelled with no infection. This has been observed in 20 species of trees. Investigators are trying to figure out what features of the tree might repel the beetle.

2.      Beetle drills into the tree and transmits the fungus, but doesn’t produce offspring. This has been observed in over 50% of the tree species attacked. We don’t know the final outcome of this interaction. Often leakage of xylem fluid is noticed on the trunk and branches. Maybe nothing bad will happen to the tree, but the tree could suffer if the xylem vessels are clogged up, which could cause dieback of branches. Damage could also make the tree more prone to attack from other pest species.

3.      Beetle drills into the tree, fungus infects the tree, and the beetle produces offspring in the tree. This has been seen in about 8% of the tree species attacked, and these species are considered true host of PSHB, and include box elder, coast live oak, and avocado. Interestingly from a natural resources perspective, it also includes invasive plants like castor bean and tree of heaven (Ailanthus). Some trees seem to suffer mild symptoms like branch die-back, while others are killed outright.

Symptoms of PSHB attack and fungus infection differ among tree species. The beetle produces a very precise, perfectly round, tiny (< 0.1 inches in diameter) entry hole in most trees. Infection with the fungus can cause a dry or wet and oily dark stain surrounding the entry holes, discolored wood, leaf discoloration and wilting, and dieback of entire branches. In box elders and avocados, a while crusty ring of sugar, also called a “sugar volcano” can be produced. Frass (wood dust from boring) may be produced, but because this can quickly dissolve in water it can be easy to miss. If the barked is scraped away, dark dead tissue may be found around the galleries.

 See link below for additional information:


Tree Care

The following is some general information regarding the care of trees. The mature trees in Hancock Park are an important amenity that beautify the neighborhood and increase property values. Unfortunately, some of the mature street trees have either succumbed to disease or have otherwise reached the end of their lives and have had to be replaced. Fortunately, we have a good program lead by the Hancock Park Homeowners Association that plants replacement trees. However, the planting of replacement trees is only the first step in the long process of tree maturation. Think children growing up to become adults. In order for the young replacement trees to grow into the mature trees that we all appreciate and value requires that the young trees receive care and attention. The trees will not flourish without your help. A relatively small investment of your time and money will produce dividends for you and the generations that will come after you. If you do not do what is required for your trees, no one else will – the City of Los Angeles does not take care of street trees. Please do your part. Thank you.


A young tree develops a stronger trunk if it is unsupported and can sway in the wind. (the technical reason is that as the trunk moves in the breeze, it releases chemicals called cytokinins, which cause the cells in the trunk to enlarge and thicken, thereby strengthening the plant tissue.) However, trees that are container grown (almost certainly the type of young tree that is planted in parkways or gardens in Los Angeles) have been closely staked their entire existence and likely do not have the strength to stand alone without staking after replanting. Combine that with the potential for strong Santa Ana winds, and staking during the first six months or year is the prudent choice.

The tree should not be staked with a single stake immediately adjacent to the trunk – even though that may be the way the tree was staked in the nursery container. Beyond not giving the tree the motion it needs to strengthen, a stake driven immediately next to the trunk risks damaging the trunk and/or roots of the tree. Instead, two stakes should be used, placed on opposite sides of the trunk, each approximately 12-18 inches from the trunk (depending upon the size of the tree). Determine where to attach the ties by using your hand to find the place where support of the tree keeps it upright. Attach the ties about six inches above that point. Use soft ties that have broad smooth surfaces – available at nurseries. Leave some slack in the ties so that the tree can move about 2 inches in each direction – that will help strengthen the trunk. Do not use wire, rope or water hose filled with wire or rope – doing so can inhibit growth and girdle the trunk. Remove the stakes once the tree has sufficiently strengthened – approximately 6 months to one year after replanting.


Trees benefit from deep and thorough watering – sprinkling with a hose for a few minutes does not provide adequate irrigation. Likewise, just watering the very top of the soil encourages root growth at the surface rather than deeper in the soil. The frequency of required watering is greatest for a newly planted tree and diminishes as the tree matures. The roots of a newly planted tree have been restricted to the area of the tree’s container – as the tree grows the roots will spread. The following are rough guidelines for a 15 gallon tree (the size of the container) receiving about 15 gallons of water at each watering (a larger tree will require proportionally more water):

First month – water twice per week
Months two and three – water once per week
Months four through seven – water once every two weeks
Months eight through twelve – water once every three to four weeks
Years two through five – once every four to six weeks
After five years, an established tree may only require infrequent irrigation.

The foregoing are guidelines and may have to be varied depending upon actual conditions, including soil type, weather, etc. Too much water can be as harmful as too little. Check the soil for moisture level at a depth of about four inches – if it is very wet, do not water. The growth of your tree will be greatly affected by it receiving adequate (but not too much) water.


Mulching around the base of a tree has multiple benefits: (1) mulch insulates the soil helping to provide a buffer from heat and cold temperatures; (2) mulch helps the soil retain water, reducing the amount needed for irrigation; (3) mulch keeps weeds and grass out to help prevent root competition; (4) mulch prevents soil compaction; and (5) mulch reduces damage to the tree trunk from lawnmowers, string trimmers or other gardening equipment.

Place a 3 – 4 inch layer of mulch around the tree. The mulch should be kept away from the trunk – at least two inches. The mulch can extend out as far as the drip-line of the tree – the outermost circumference of the tree’s canopy. However, recognizing that may be more mulch that you want, a circle or square area of mulch that stretches 2 feet from each side of the trunk will still be beneficial. Mulch is commercially available from a variety of sources, including home improvement stores. Wood or bark chips are good tree mulch and can provide a well-manicured appearance. Use chips that are approximately 1-3 inches in size.


Trees can benefit from feeding (fertilizing) – it will help stimulate growth and better establish the trees. However, a newly planted tree should not be fertilized for a couple of months to let it first get acclimated to its new location. Most of the root activity through which trees draw in nutrients occurs in the top 12 or so inches of the soil. Among the possible ways to feed a tree are dry fertilizer spread on the surface around the tree and liquid fertilizer injected into the soil. Dry fertilizer should be spread evenly over the entire root zone which can extend two to three times the width of the branches. Remember that some of the root zone may have already been fertilized when fertilizer was applied to the lawn or planting bed under or adjacent to the tree. Sprinkle the fertilizer on top of the soil or mulch and water lightly. Since the fertilizer will quickly move through the mulch there is no need to remove it or to place the fertilizer below it. Do not dump dry fertilizer in piles – doing so can cause the roots below the fertilizer to be burned and die. Liquid fertilizer can be injected into the soil using a root feeder – the Ross Deep Root Feeder is available online or at garden and home improvement stores. This is the link to the Home Depot: http://www.homedepot.com/p/Ross-Root-Feeder-12044H/100328642#.UUjKHRdweSo. It uses solid fertilizer tablets that are dissolved in water in the feeder and the liquid is injected through the feeder’s injector spike. In Los Angeles, trees can be fertilized once in the spring and once in the fall – the tree roots continue to grow in the winter, even if the leaves fall off or appear dormant. Trees can be overfed – more is not better. Too much feeding can result in too much growth that is weak. Consult with a qualified nursery regarding which fertilizer to use. Do not use so-called “weed and feed” fertilizers that incorporate a herbicide for weed control – the herbicide can harm your tree.


Young trees require proper pruning to achieve a strong structure and desirable form. Among other things, a tree that is not pruned is going to be more susceptible to damage from the wind or other elements. A tree that is not properly pruned when it is young will require more difficult and frequent corrective action as it matures. Generally, the goal of pruning is to establish a strong central trunk with sturdy, well placed branches. Meaningful pruning – beyond the removal of dead or damaged branches – should usually wait for a couple of years after planting to allow the tree to fully recover from the shock of transplanting. Proper pruning requires training and skill and often is better left to a professional. In the case of parkway trees, the city will not prune on a regular basis and the burden is upon the homeowner to ensure that the trees are properly cared for, including pruning.

The two trees depicted below were planted at the same time, in approximately 2006. The tree on the right has received regular tree care, including watering, feeding, mulching and pruning (it was pruned shortly before the photo was taken). The tree on the left essentially has been uncared for since it was planted. The difference between the trees is obvious. The tree that has received proper care has a larger trunk, is much taller and fuller and has a better form. In seven years it has become a handsome tree that helps beautify its street. The tree that has not been regularly cared for still looks like a recently planted tree and if it can recover from its neglect will take many more years to develop into a meaningful street tree like the one on the right.

Tree Care and the Drought

Caring for trees in a drought!

Trees are generally the most valuable asset in the home and business landscape and when their health declines, the most difficult and expensive to replace. Considering their value, and the time needed to grow to maturity, ensuring the survival of shade trees should be a top priority for landscape professionals. According to local certified arborists, a typical large tree has a replacement value ranging from several to tens of thousands of dollars. During times of drought, landscape retention decisions should be made based on value, risk assessment, and the cost and ease of replacing assets of equivalent size.

With Governor Brown’s recent declaration “This [is an] emergency and I’m calling all Californians to conserve water in every way possible.” It is imperative that we are able to both meet his call to action as well as preserve the irreplaceable mature tree canopy.

Steps for Conserving Water and growing Healthy trees

Whether trees are planted in turf, mixed beds, or alone, the following steps will help to conserve water while also improving the tree’s ability to utilize the water it
is offered.

Protect Your Parkway Trees!  Water them once a month.

* You can simply drag a hose to the drip line, to find the drip line look  up and see where the outer edge of your tree canopy is…and water slowly until the soil is damp 16 to 18 inched down.

Improve Soil Structure

Properly aerated soil is an essential factor for the functioning of a tree’s root system and water permeability.

* Remove excess soils burying the flare of the tree trunk in a careful manner to minimize damage to the root system.

* Remove rocks and other impervious materials from beneath the tree canopy.

* Aerate the lawn so that roots of mature trees are better able to access water and oxygen.

Reduce Competition

* Remove all weeds and grass within four feet of the base of young trees. For trees planted alone or in mixed beds, this is also recommended.


Leaves and chipped wood are ideal mulch materials. Organic mulch will break down and create nutrient-rich compost that will keep soil evenly moist, conserve water, and insulate roots while providing essential nutrients for the tree.

* Place mulch 4 to 6″ deep, keeping it 4″ away from the trunk, around all trees where the landscape allows.

Monitor Soil Moisture

* Place a shovel, small spade or a screw driver into the soil to a depth of 6–8″ (near the trunk for a young tree and under the drip line for a mature tree).

* Squeeze a handful of soil, if it feels dry and crumbly add water.

Please have a look at the important information in this article/link from Tree People! It provide information on how to care for trees during the  drought. We need to protect our tree canopy.




137 North Larchmont Boulevard # 719

Los Angeles, CA 90004

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