Best Time to Prune Las Vegas Palms

Saturday, April 28, 2012

Yellowing and browning of fronds
due to cold winter temperatures

Best Time to Prune Las Vegas Palms

Cold temperatures of winter often produce yellowing or browning of palm fronds of several different palm species growing in the Las Vegas Valley.  With the warmer temperatures of spring the tendency is to remove the damaged unsightly fronds as soon as possible.  For the homeowner that may only have a few trees, which they prune or have their gardener prune, timing is not generally an issue.  However, for the commercial property or HOA that may have a considerable number of palms, which are typically pruned by professional tree companies, resisting that initial urge to prune early could save money and provide more attractive palms during the course of the summer. 

Early spring pruning may remove unsightly fronds; however, the fruiting structures called inflorescence, garlands, or flower stalks may not have begun to grow or elongated sufficiently thus they are not removed with the fronds.  With increasing temperatures of spring and summer the flower stalks will grow at a very rapid rate emerging from the tree’s crown, along with new fronds.  Flower stalks of Mexican Fan Palms may reach lengths of 10-15 feet and will produce thousands of creamy-white flowers with a hint of pink and eventually small ½ inch berries or drupes that will fall to the ground becoming a nuisance in landscape and hardscape areas. 

Pruning palms late spring or early summer, just

prior to maturation of fruit, will allow for removal

of unsightly fronds, flower stalks, and fruit; 

therefore, only one pruning operation will be 

required for the season.

The above two Mexican Fan Palms were originally pruned 

in April prior to development of the inflorescence (flower

stalks).  By late June early July the inflorescence have 

fully developed producing an unsightly crown.  To improve

the appearance of the trees a second pruning will be 

required.

 

    

The Phoenix dactylifera in the above photo
were pruned late June.  Both unsightly and/or
damaged fronds were removed as well as the
inflorescence and fruit.  Only one pruning is
required for the season.  

                 

Roses Not Doing Well......Maybe They Need Citrus Food???

Soils of the Las Vegas Valley vary considerably in their physical and chemical properties, therefore growing plants for the garden or the landscape can often be challenging.   With many different soil problems facing the gardener, deficiencies of the essential plant nutrients or elements is the most common across the Las Vegas Valley.  Plants require sixteen essential elements for proper growth and development (17 or 18 elements when referred to as ‘beneficial elements’ rather than ‘essential’).  The elements may be divided into three groups based on the quantity each is used by plants.  The three groups are primary, secondary, and trace.  The primary elements nitrogen, phosphorus, potassium, carbon, hydrogen, and oxygen are used in the largest quantities followed by the secondary elements calcium, magnesium, and sulfur which are followed by the smallest quantities or trace elements of iron, zinc, copper, manganese, molybdenum, chlorine and boron.  It’s important to note that although nearly all plants require the same 16 essential nutrients or elements, they don’t always require them in the same quantities or more importantly, in the same proportions.

In general, in uncultivated Las Vegas Valley soils we find deficiencies consistent with the trace elements iron, zinc, copper, and manganese; however, availability of the primary elements nitrogen and phosphorus will vary from area to area with the exception of the primary element potassium which in most cases is found in relatively  high concentrations.

By providing the nutrients that are deficient in the soil, through the application of fertilizers, we can often improve growth and development of our garden and landscape plants.  Providing proper nutrition will also often increase resistance to insects, disease, drought, etc.  Determining which nutrients are deficient requires laboratory testing of the soil and plant tissue.  This process is often done with commercial landscapes; however, is rarely done with residential landscapes.  For this reason, fertilizer manufacturers produce fertilizer formulations with varying proportions of the primary elements nitrogen, phosphorus, potassium, and may also include secondary and trace elements for specific plants or plant types that are growing in average soils.  Thus, on the nursery or garden center shelf we find fertilizers identified as ‘Tomato Food’, ‘Rose Food’, ‘Citrus Food’, ‘Palm Food’, ‘Turf Supreme’, etc.   On the front of the container of each of these fertilizers is three numbers each separated by a hyphen        (14-7-5).  Each number represents a percentage by weight of nutrient in the container.  In this example it equals 14% nitrogen, 7% phosphoric acid (phosphorus) and 5% potash (potassium).

Unfortunately, Las Vegas soils are rarely average.  If your roses are not responding to the ‘Rose Food’ (6-12-4) and soil and plant tissue tests indicate you need twice as much nitrogen, half as much phosphorus, and twice as much potassium then perhaps you need to try the ‘Citrus Food’    (14-7-7).

Landscape professionals select specific fertilizers based on laboratory soil and plant tissue testing, plant requirements, and field observations.    Such fertilizers are referred to as ‘site specific’.  Utilizing site specific fertilizers will meet plant requirements for proper growth and development while keeping costs at a minimum and protecting the environment. To the landscape professional titles such as ‘Tomato Food’, ‘Citrus Food’, ‘Turf Supreme’ have little value. 

      

Move Over Pentas.......Vinca Is Back!!

Move Over Pentas…….Vinca is Back!! 

     

Vinca Cora Cascade 'Cherry Red'  (Venetian/Palazzo)

The use of Vinca or Periwinkle as a summer annual in the Las Vegas Valley has declined significantly over the past 20 years.  Most recently, the use of Vinca has been limited to residential landscapes with very little use in commercial applications.  The reason for the decline has been the plant’s susceptibility to 'Aerial Phytophthora’ also known as ‘sudden death’ disease. 

Vinca Cora 'White'
(Venetian/Palazzo)

Aerial Phytophthora is a soil-borne fungus that is often referred to as a water mold since it is most often associated with wet poorly drained soils.  The fungus  produces zoospores from sporangia that swim in water films or may be splashed from the soil surface to plant foliage where initial infection occurs.  The disease causes the leaves to collapse as it progresses down the petiole to the stem (node) where it kills the tissue producing a sunken lesion, followed by the stem also collapsing.  Symptoms of collapsed leaves are evident in a few days of infection with loss of the entire plant within one to two weeks.  Due to difficulty of control, which usually involved fungicide applications (foliar/drench), crop rotation, etc. and the increased availability of new warm season annuals including Pentas, Vinca quickly lost its popularity. 

Vinca Cora 'Burgundy'

The loss of Vinca from Las Vegas summer landscapes was huge!  This was a plant that could thrive in heat while producing almost a tropical effect with its dense dark green glossy foliage and masses of long term blooms of a wide variety of colors.  However, this summer the homeowner will see a new Vinca, one that has undergone a new makeover.  The new plant will be called Vinca ‘Cora’ and will be Phytophthora resistant!

Vinca ‘Cora’ is a new series F1 hybrid developed by Goldsmith Seeds and has taken over twenty years to develop.  Eight colors are available including Apricot, Burgundy, Deep Lavender, Lavender, Pink, Punch, Violet, and White.  Mature plants reach 14-16 inches in height with a 22-25 inch spread.  Vinca ‘Cora’ has been used commercially for a couple of years, including at the Venetian Palazzo Resort, starting in the summer of 2009 where it proved to be a huge success.  Up until now the availability of Vinca ‘Cora’ has been somewhat limited to the homeowner.    

Vinca Cora 'Deep Lavender'

In addition to the standard Vinca ‘Cora’ Goldsmith Seeds has also developed Vinca ‘Cora’ Cascade!  This has proven to be a wonderful flowering plant for hanging baskets, pots, or anywhere bright colored flowers in a cascading form in high heat environments is desired.  New colors include Lilac, Magenta, Peach Blush, Polka Dot, and Cherry Red.  Cherry Red proved to be an exceptional performer at the Venetian/Palazzo Resort.   

Watch for these great new Vincas late spring early summer in your local nursery and garden centers.  

Landscape Management Programs for HOA's

Landscape Management Programs for HOA’s

                                                               

During the past thirty years I have had the opportunity to work with many different Homeowner Associations in terms of landscape maintenance and management.  This has involved onsite troubleshooting of plant and irrigation problems as well as developing site specific landscape management programs.    

A good landscape management program not only meets the day to day upkeep required of landscapes, but also ensures long term health of plants and overall aesthetics.  A good site specific landscape management program will help in keeping maintenance costs down while keeping long term property values up. 

In the Las Vegas Valley each HOA Development, of condominiums, townhouses, or single family residences, common area landscapes of each are often unique.  Landscape use or function often varies from property to property as well as plant  types, soil types and conditions, and micro/macro climates that create the landscape environment.

Landscape management programs can be provided or developed by a landscape maintenance company or the Homeowners Association.  Most landscape maintenance or landscape management companies utilize landscape maintenance programs in maintenance of their properties.  Most often the programs are generic although a few landscape management companies may provide site specific programs. 

A few years ago I was asked by a Homeowners’ Association to assist in selection of a landscape maintenance company to maintain their condominium development.  The HOA was experiencing a high turnover in landscape maintenance contractors which resulted in a negative impact on the condition of the landscape.  The HOA did not have a site specific landscape maintenance program and was dependent on each contractor to provide a generic program with their bid.  In addition, there was not any agreed upon ‘standard level of maintenance’; therefore, bids submitted by contractors were wide spread ranging from $3,000 to $5,000 per month and each time the HOA would accept low bid.  Awarding the contract to low bid is acceptable if the difference between the low and high bid are close and fall within an acceptable range. To help this HOA it was necessary to develop a site specific landscape maintenance program that would become an integral part of the bid and contract specifications.  For the first time contractors were bidding ‘apples to apples’.  Bids came in at $3,800 to $4,100.  At first glance, the $3,800 may seem considerably higher than $3,000, but as I once heard a wise landscape consultant say at a landscape maintenance conference, “it costs, what it costs, what it costs”.  Landscapes are expensive to install and when properly maintained improve the quality of our lives and increase the value of our property. 

Site specific landscape management programs also place control for both short and long term landscape health and aesthetics in the hands of the homeowners and the property management company.  Landscape cultural practices often involve the application of fertilizers, pesticides, and other chemicals all of which carry a certain degree of liability for the HOA and property management company.  Therefore, it is important to have the control necessary to provide not only an attractive landscape, but also a safe landscape. 

Turf Reduction - Problems For Some?

Young Ash tree displaying symptoms
of severe drought stress due to a
poorly designed irrigation system.

Turf Reduction  -  Problems For Some

In December of 2004 at the conference of the Colorado River Water Users Association a $200 million conservation initiative was announced to assist public agencies to save water through turf-reduction programs.  Southern Nevada Water Authority’s ‘Water Smart Landscape Rebate Program’ has since helped both homeowners and businesses in reducing landscape water use while creating aesthetically pleasing desert landscapes. 

In general, the rebate program has been a tremendous success.  However, there have been a few problems associated with the conversion of turf to desert landscape.  The most common problem involves maintaining the health of trees that once grew in large turf areas where they enjoyed high soil moisture levels, cooler soil temperatures and higher humidity and now find themselves in an arid environment.  Trees are one of the strongest and most important elements of a landscape and during any landscape conversion process their preservation should have a high priority. 

During the conversion process not only is the turfgrass removed, but so is the overhead irrigation system.  With the overhead turf irrigation system maintaining high soil moisture levels over large areas, mature trees could often expand their root systems beyond their dripline.  Conversions called for the replacement of overhead irrigation systems with a more efficient surface or subsurface drip-type system.  In most cases, the new drip-type irrigation system would not be designed to continue to provide coverage to 100% of a large or mature trees existing root system.  The new irrigation design concept would attempt to meet a minimum of 70% coverage of the existing root system.  Obviously, a 30% loss of irrigated root zone, especially the perimeter feeder roots, is going to cause stress to trees.  However, with care and proper cultural practices most trees will adjust and will continue to thrive.  However, when drip-type irrigation systems are not properly designed slow decline and loss of established trees may occur. 

Poorly designed irrigation
system caused drought
stress predisposing tree to
Sooty Canker (Fungus)

This past summer I consulted on several projects involving tree decline and death on HOA properties that had undergone a prior turf-reduction and landscape conversion.  Poorly designed drip-type irrigation systems were most often responsible.  Tree conditions ranged from healthy to severely stressed or even death.  In general, the healthier trees were also the smaller trees.  This was due to the trees having smaller root systems thus being less impacted by the reduced size of the new irrigation system as well as less root disruption or damage during installation.

Bark of dead branches
split open revealing a black
dusty mass of Sooty Canker
fungal spores 

Trees that are stressed due to insufficient irrigation are weakened and can become subject to a whole new set of problems.  Environmental factors such as sunscald or insect and diseases that previously were not an issue now become major problems.  A good example can be seen in the attached photographs of a Las Vegas townhome complex that had a few years earlier undergone a landscape conversion involving extensive turf reduction and the installation of a poorly designed irrigation system.   The photographs were taken late summer.  The previous fall and late winter we received rain and conditions were fairly moist.  This was followed by a hot windy summer.  During this time the fungus ‘Sooty Canker’ (Hendersonula toruloides) easily established itself in the weakened trees.  The disease in one season had severely damaged or killed most of the large ash trees. 

Throughout many areas of the Southwest we are seeing the use of turfgrass being reduced in landscapes with landscape designers now placing more emphasis on turf functionality.  Aesthetics is still important; however, we can still create attractive landscapes with less turf.  It’s also important that we continue to reduce the amount of established turf in an effort to conserve one of our most precious natural resources.  However, it’s also important to maintain the health of our large and mature trees during the process of turf reduction.   

  

Queen Palms - In Las Vegas???

Queen Palms  -  In Las Vegas???

Growing up in Southern California in the 70’s the Queen Palm was one of my favorite palms.  Of the many different species of palms growing in California landscapes the Queen Palm (Syagrus romanzoffiankum) provides one of the best tropical effects with its smooth straight trunk, soft bright graceful green feather-type fronds that sway with the slightest breeze. 

When I moved to Southern Nevada in 1979 I was quite surprised to find the queen palm being used in landscapes.  Environmental conditions of the Las Vegas Valley with colder winter temperatures combined with highly alkaline soils produce less than desirable growing conditions for this palm. 

March 2011 Las Vegas

March 2011 Las Vegas

Some degree of damage to frond tissue occurs nearly every winter.  Trees are hardy to the mid 20’s with death often occurring in the low 20’s to high teens.  During the winter of 90-91 official temperatures dropped into the single digits and nearly every Queen Palm in the Las Vegas Valley was killed.  In addition, Southern Nevada’s highly alkaline soils (high pH) severely limit the availability of the essential soil trace elements or nutrients required for proper growth and development, especially manganese.

March 2011 Las Vegas

March 2011 Las Vegas

The damage to the palms in the photos is not unusual. It's also important to note that this past winter was average or typical and would not be considered exceptionally cold.  Without TLC these palms will not generally recover replacing all the dead fronds until late summer when its only a short time until the process starts all over again.

So why do we still see Queen Palms installed every spring and summer in Southern Nevada Landscapes?  Because the palms are inexpensive, readily available from Southern California, provide a nice tropical effect, and are very attractive in nursery growing containers as they arrive in Las Vegas from Southern California.

                                      

Mexican Evening Primrose - 'Bug Alert'

Mexican Evening Primrose ‘Bug Alert’

With cold winter temperatures behind us and the onset of warm spring weather Mexican Evening Primrose can be found actively growing throughout the Las Vegas Valley with the plants soon to be in full bloom.  However, the warmer temperatures and lush new plant growth also brings out the flea beetle. 

Adult flea beetles feed on plant foliage.  They are very small insects between 1/16 inch to 1/4 inch long.  The color of the insects varies dependent on species with metallic bluish-black most common in our area.  Flea beetles often hide and are difficult to see without close observation of the plant foliage.  In most cases, the presence of the insects are first observed when the new lush foliage begins to look tattered.  The beetles can do a considerable amount of damage in a very short period of time.  The insect will decline in numbers with the onset of hot summer temperatures; however, a second cycle of beetles may appear once again late summer.

To keep your plants healthy and ensure an attractive spring bloom will require early detection of the pest.  Flea beetles are easily controlled with insecticides. 

  

Mesquite - A Las Vegas Landscape Challenge?

Over 30 Mesquite trees in this Las Vegas parking lot were
blown over due to a strong summer wind.  Photos identify
 insufficient root development while considerable top
growth has taken place.

Mesquite – A Las Vegas Landscape Challenge?

In Southern Nevada we have been using mesquite trees in both commercial and residential landscapes for many years.  Found throughout the southwest, the mesquite is quite tolerant of Las Vegas environmental conditions.  Although there are different species, the Chilean Mesquite (Prosopis chilensis) and the Texas Honey Mesquite (Prosopis glandulosa) are most often the species of preference. 

Large beautiful mesquite trees that enhance our landscapes do not naturally occur, but are often a product of years of determination and hard work.  Mesquites do not grow naturally into upright single or multiple trunk trees with large full crowns.  In there natural environment trees are often found growing in thickets with their growth habit similar to a very large sprawling belligerent thorned shrub.  Young nursery trees require considerable training, mostly in the way of pruning and staking, to produce a saleable upright growing tree (notice all of the tree support stakes next time you see these container grown trees in the nursery).  As trees increase in size and their initial upright form has been established less work is required although not entirely eliminated. 

Poor root system development is another issue we are constantly dealing with in nursery container grown mesquites.  In the wholesale nursery growing environment mesquites grow very rapidly.  The trees are initially grown in small containers and are upsized or repotted to larger containers as they grow and develop.  With such rapid growth it is not uncommon for root problems to develop in terms of girdling roots and/or root-bound plants.  Trees with root problems may be upsized several times with the potential of the same problems reoccurring.  Although root development may be quick, top growth is generally faster.  Therefore, it is possible to not only have a tree with poor root structure, but one in  which the top growth far exceeds and is out of  proportion with the size of the root system.  Even  a nursery container tree with good root structure that is also in proportion with the tree’s top growth, when placed into a landscape environment where it receives frequent irrigation, fertilizer, etc. may once again experience top growth exceeding root development.  This is the reason we often see trees tied to support stakes for several years following installation. 

Loss of newly installed mesquites to winter desiccation is another problem common to Southern Nevada.  Most nursery trees are produced in Southern California and Arizona where winter temperatures are mild.  Planting of these trees in Las Vegas mostly occur during spring and summer months.  With warm weather, irrigation and fertilization trees grow rapidly producing soft tissue.  As often occurs with new landscape installations heavy irrigation continues into the fall and early winter and trees do not have an opportunity to harden off prior to the onset of cold and often freezing temperatures.  With lush growth, soft tissue and wind combined with cold temperatures desiccation and death may occur. 

Rules of Thumb (Green Thumb):

ü      The smaller the better!  Small containerized nursery trees are less likely to have root problems and will often out perform larger containerized trees.  Unfortunately, small container sizes such as 5 gallon are generally not available since the trees will quickly grow to 15 gallon or larger and thus have a greater cash value to the wholesale grower.  Always inspect the tree’s root system prior to planting.  Root pruning may be necessary to correct problems or deficiencies.

ü      Strong, healthy, upright, and attractive mesquites don’t just happen by luck!  Trees will also require considerable training following installation.  Put as much emphasis on developing a strong root system as you do on developing the above ground structure.  This may require heavy pruning of the top growth to keep it proportional to the developing root system.

ü      Don’t over fertilize.  In most cases mesquites require very little fertilizer.  Too much fertilizer will often increase top growth at a faster rate than root growth producing a top heavy tree.

ü      Irrigation system design needs to meet the newly installed tree’s requirements as well as the tree’s long term requirements.  Improperly designed irrigation systems can restrict as well as create rooting problems which may lead to eventual tree failure. 

ü      Keep installation of trees in turfgrass areas to a minimum.  Turfgrass irrigation and fertilization encourages shallow rooting and excessive top growth.

ü      Heavy pruning should only be done during the coldest time of the year.  Trees produce heavy sap flow during warm temperatures.  Large pruning cuts made during warm weather may produce sap flow to the exterior of the tree for months or in some cases years. 

ü      Don’t fertilize newly installed trees and reduce irrigation in the fall to harden off trees for winter. 

Purple Flowering Plum - Disappearing From Las Vegas Landscapes

Purple Leaf Flowering Plum (Prunus cerasifera)

During the past twenty-five years we have seen a tremendous decline in the purple leaf flowering plum trees across Southern Nevada.  The losses have been primarily due to the insect the flat head borer.  Today flowering plum is used in limited quantities in commercial landscapes with most tree installations occurring in residential landscapes.  The flat headed borer will continue to thrive in Southern Nevada and many more plums will be lost each year, especially trees that are stressed due to adverse cultural or environment factors. 

Keeping trees strong and healthy through good cultural practices including fertilization, irrigation, pruning, and pest control will greatly reduce problems with borers.  Trees should be fertilized mid to late February, late spring, and again early fall.  Irrigation system design should meet the needs of newly installed trees as well as meet the eventual requirements of a mature tree.  Trees should be professionally pruned each winter to ensure good structural development of the branches that form the crown but should also encourage good density.  Excessive thinning may promote sunscald of the internal branches which will encourage borer infestation. 

In addition to borers, purple leaf flowering plums are attacked by chewing-type insects and foliar diseases.  These pests along with poor cultural practices reduce leaf size thus increasing potential for sun scald of internal branches within the crown.  Proper cultural practices including fertilization in conjunction with two foliar applications of an insecticide/fungicide mix will greatly increase leaf size and overall density of the tree’s crown.  The insecticide/fungicide mix should be applied to the tree’s branches and foliage following spring bloom with the second application six weeks later.