HORTICULTURE CONSULTANTS INC. 221 Misty Garden St. Henderson NV Telephone: Fax:

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Dorothy Ward
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1 S i n c e HORTICULTURE CONSULTANTS INC. 221 Misty Garden St. Henderson NV Telephone: Fax: jpsathci@aol.com January 26, 2015 Palo Verde Meadows Property Owners Association c/o Buck Reynolds Management Company 1834 Highway 95 Bullhead City, Arizona Re: HOA Common Area Trees Dear Palo Verde Meadows POA Board Members: This letter is a summary of my onsite meeting and inspection of the mesquite trees on the river peninsula and trees within the community park with Ms. Barger, Mr. Holland, and Mr. Stockman on January 20 th. Mesquite Trees River Peninsula The peninsula separating the Palo Verde Meadows development lagoon/marina from the Colorado River was found to contain numerous Honey Mesquites (Prosopis glandulosa var. torreyana) that were infested with Mesquite Mistletoe (Phoradendron californicum). Honey Mesquite is wide ranging, from Texas west to California, and south into Mexico. The tree is considered a phreatophyte and is commonly found in close association with water sources such as rivers or shallow aquifers. As with most Mesquites, the Honey Mesquite can produce a root system that will grow deep into the soil profile to access water. The species will also produce a shallow root system to access water from limited and infrequent rainfall. The trees on the peninsula were originally maintained utilizing an automatic irrigation system. The irrigation system at the current time is no longer servicing the trees; however, the trees have now grown deeper into the soil profile and are able to access water from the shallow aquafer produced by the adjacent river. Establishment of any new trees would require use of the irrigation system. Most of the mesquites observed were infested with mistletoe to some degree. Mesquite Mistletoe is a leafless parasitic plant that produces seed which is generally spread by birds from one plant to the next. The seed when deposited on a host plant will germinate and grow through the bark into the host where it develops a root like structure called a haustorium that adsorbs water and nutrients from the host. Trees infested with mistletoe may survive for years with the mistletoe killing off sections of the host while the host generates new growth in response. Trees that are also stressed due to other factors including unfavorable environmental conditions, including insufficient rainfall, may not be able to produce new growth and thus the trees may die at an increased rate. There is no known cure for this parasite; however, keeping plants healthy may assist in reducing infestation. Generally, pruning or removal of the infested branches or portions of the tree is currently the most common practice for control. Unfortunately, there is no way of know how far the haustorium has penetrated the plant s conductive tissues. If a portion of the haustorium remains following removal of an infested portion of the plant the mistletoe may regenerate. Removal of the infested portions of the tree will help to reduce or slow infestation of other trees in the vicinity. Currently, many of the trees are unsightly due to mistletoe infestations. Pruning of the trees to remove the mistletoe will improve their appearance. Depending on the degree of infestation pruning may range from light to severe. Mesquites are quite tolerant to pruning, even severe pruning will most often not kill a tree. Pruned trees will generally

2 recover quickly with new growth since trees will generally have well established root systems. Pruning will also reduce stress on trees not only due to the removal of the mistletoe that is adsorbing a tree s water and nutrients but also by reducing a tree s transpiration rate, thus the tree requires less water. Currently, with the drought condition of the last several years and the lowering of the river which lowers the water table there is less available water for the trees. Removal of some of a tree s top growth will bring the transpiration rate more in line with the available water. PHOTO A PHOTO B Photograph A above illustrates a Mesquite that has been inundated with mistletoe in the upper portion of the tree s crown. Some of the crown has begun to die with the tree responding with new growth close to the base or at the lower trunk(s) of the tree. The tree is severely stressed, unsightly, contains considerable mistletoe seed that can be transmitted to other trees in the vicinity, as well as a fire hazard due to tourists boating and picnicking along the river. Consideration may be given to crown reduction, which in this case would most likely be relatively severe. Specifically, to what extent the tree would be cut back is difficult to determine from the photograph or actually even onsite until the work has actually begun. It is possible that top growth may be removed back to the trunk(s) with just several primary scaffold limbs remaining. Photograph B illustrates a Mesquite that had been previously pruned several years prior to an upright single trunk form. The tree has not received any pruning over the past couple of years. The tree has a moderate infestation of mistletoe; however, through selective pruning the mistletoe can be removed and additional pruning consisting of crown cleaning and shaping will greatly improve the aesthetics as well as prolong the life of the tree. Mistletoe infestation negatively impacting the health and condition of the many mesquites on the peninsula range between the two extremes illustrated above. Although the Mesquite trees on the peninsula are considered part of the natural landscape basic pruning practices and techniques should still be employed Debris Not Removed Following Pruning when pruning work is done. Photograph C illustrates a Mesquite tree that appears to be indiscriminately hacked back close to ground level. Although mistletoe could have conceivably infested the tree close to ground level there is a good chance that this is not the case. Following pruning all debris, including mistletoe, should be immediately removed from the site. Pruning is less stressful on the trees if conducted during the winter months (January). It is at this time sap flow within the tree is reduced and there is less bleeding from the pruning cuts of large limbs PHOTO C thus the cuts dry and heal more quickly. Page 2

3 Palo Verde Meadows Park Palo Verde Meadows Park is centrally located within the development. The park is quite large with warm season bermudagrass throughout with several fresh water lakes and several species of trees including Aleppo Pine, Mondel Pine (Afgan Pine), Olive, Eucalyptus, and Elm. Many of the trees are fairly mature with new or young trees also currently being installed. Per our onsite discussion and observations approximately 20 of the larger trees were recently pruned and there is concern as to whether the pruning procedures meet approved arboriculture standards. Pruning was conducted for several reasons including to reduce the overall height (trees have failed in the past due to high winds), crown PHOTO D PHOTO E cleaning (removal of dead wood, crossing branches, collection of debris, etc.), and to improve homeowner views. Photograph D illustrates two fairly mature Eucalyptus trees growing in a turfgrass area. The trees receive irrigation from the turfgrass irrigation system and therefore the majority of their root systems will be relatively shallow and most likely located from the soil surface to 12 (18?) inches in depth. With potentially shallow root systems and tall large crowns the trees do present a certain degree of hazard. Photograph E illustrates a Eucalyptus tree with a fairly dense crown due to excessive internal growth within the crown as well as dead branches. In addition, poor pruning practices have produced a tree with the center of gravity or weight of the crown off-center of the trunk. The crown is asymmetrical, and the density of the crown restricts air movement through the tree. These conditions combined with potentially a shallow root system increases the hazard potential or the possibility of tree failure. In an effort to reduce potential tree failure several trees were pruned utilizing a pruning technique known as crown reduction which is used to reduce the size of a tree. This procedure is extreme and success is often dependent on PHOTO F PHOTO G PHOTO H species as well as age and condition of the tree. In general, older trees requiring large cuts do not respond as well as young smaller trees requiring smaller cuts. Large cuts do not heal quickly and decay or rot is often a concern. The procedure involves cutting limbs back to their point of origin or back to a lateral limb capable of sustaining the remaining limb. When cutting a branch back to a lateral, no more than one-fourth of its foliage should be removed, if practical. A common rule of thumb is the remaining lateral branch must be at least one-third the diameter of the removed portion. Crown reduction was utilized on the trees in the three photographs above. Photograph F was pruned recently, photograph G appears to have been pruned a year prior and C two to three years prior. It quickly Page 3

4 becomes apparent that considerable new growth as developed at or near the terminal ends or cuts of the primary limbs. Although crown reduction may initially reduce the size of the tree it will result in additional work to keep the tree healthy and structurally sound. When excessive growth develops as in photographs G and H crown restoration should be considered. Restoration consists of the selective removal of some new branches or watersprouts, stubs, and dead branches to improve a tree s structure and form. One to three new branches or sprouts should be selected from the ends of cut limbs to become permanent branches and to re-form a more natural-appearing crown. Selected vigorous sprouts may need to be subordinated to control length growth and ensure adequate attachment for the size of the sprout. Restoration usually requires several prunings over 2-3 years. It is also apparent in photographs G and H that neither tree has been pruned since the initial crown reduction. If crown reduction and restoration are not done properly a fast growing tree may regain its original height with increased density and weight of the crown in only a few seasons thus creating a greater liability. Crown reduction was used on the Eucalyptus in photograph I to reduce the height and width of the tree. The tree still remains quite high following pruning. Within two seasons new growth from the terminal ends of the cut branches will exceed the height and density of the original crown. Consideration may have been given to additional reduction of the height even though large cuts would have been required thus increasing the potential for decay and reduced recovery response. A better selection and orientation of cut limbs could have also been employed to reduce the number of STUBS new shoots that will develop in a small area. In addition, pruning should not produce branch stubs that remain following limb removal. The stubs may also produce a large number of new shoots or branches tightly grouped in one spot. Too many cut limbs remaining in a small area. This will produce a large tight mass or grouping of new sprouts or branches. PHOTO I Crown reduction, although not a popular pruning technique, in some cases is required and can be effectively accomplished (depending on tree species, age, size and condition); however, as illustrated, can increase maintenance due to restoration pruning that may be required for several seasons. In addition, per Mr. Stockman, trees cannot be accessed with a bucket truck and all pruning must be done by tree workers physically climbing the trees, which increases labor costs. New trees are currently being installed into the park area (PHOTO J ). Mr. Stockman indicated that new tree locations were primarily based on homeowner requests and not on a Tree Master Plan. Page 4 PHOTO J

5 Trees are the most important element in most landscapes. Trees provide aesthetic value, increase property values, and improve many aspects of the environment. Since trees are a long-term investment selection, installation, and maintenance factors should carefully be considered. Based on our onsite meeting and observation of the Palo Verde Community Park the following recommendations are provided for your review: 1. Conduct a tree inventory and evaluation of all trees. A tree inventory and assessment typically includes: a. Identification of each tree species and field labeling of trees for future tracking and identification. b. Development of a site plan identifying location of each tree per a above. c. Inspection of current health and condition including longevity and identification of any major issues including trunk cavities, disease, insect damage, broken limbs, decay, etc. d. Special requirements including pruning, fertilization, irrigation, etc. e. Identification of tree(s) recommended for removal due to poor health, disease, high maintenance costs, and/or a liability for the Association. 2. Develop a new tree installation and replacement master plan. The plan should reflect immediate, short-term, and long-term requirements and concerns: a. Develop a tree palette that is consistent with existing trees, homeowner and community requirements, environmental conditions, maintenance capabilities, and budget. b. Identify locations of new tree installations on a site plan and excel sheet based on immediate, short-term, and long-term requirements. Select tree locations based on replacement requirements, overall aesthetics, maintaining a central theme throughout the park, and requirements of homeowners both directly adjacent the park and in the surrounding areas. 3. Develop pruning standards specific to tree species and the site including access capabilities. Pruning standards may become an integral component in a request for proposal for services (RFP) when obtaining bids for tree work. 4. Develop a standard RFP/Contract format that includes: a. Pruning Standards b. Contractor Requirements (Insurance Requirements, etc.) c. Scope of Work: Scope of work would identify specific trees requiring specific work. Not all trees require pruning every year and pruning requirements varies from tree to tree and year to year. With each tree labeled onsite and a corresponding site plan identifying tree locations the bidding process is simplified for the Association, Association Management Company, and the Contractor. Tree work is best accomplished during the month of January for deciduous trees. With the moderate winter temperatures of the Bullhead City Area evergreen trees can also be pruned at the same time. Identifying specific tree requirements for the Scope of Work would require a tree inspection late summer (August) with a RFP prepared and submitted to prospective tree maintenance contractors by the first of September. Completed bids should be returned to the Association by October 1 st, the contract awarded by November 1 st, and the tree work to be completed in January. If the recommendations above are considered, I would recommend not installing any more new trees at this time. I would also recommend prior to committing or conducting any additional pruning of the park trees a thorough review of the current pruning practices be reviewed with your current tree maintenance contractor. HCI is available to assist with these recommendations and would be able to provide a proposal for services upon request. Page 5

6 If you have questions concerning this report or if I may be of further assistance please contact our office at your convenience. Respectfully submitted, John P. Smith Horticulturist, ISA Certified Arborist, NV Registered Landscape Architect, NV Pest Control Primary Principal jps

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