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Monday, May 20, 2019

My Opinion of Pines for the Hot Desert


Q. What is your opinion of pines as landscape trees in our desert climate? We have quite a few planted in our complex and our HOA is discussing whether we should get rid of them or not because of their liability and water use. Our landscaper tells us they have borers.

A. I’m a little suspicious of the borer diagnosis in pine trees since it is rare for them. Have that diagnosis confirmed with a second or third opinion. Aleppo Pine gets a blight that causes browning of needles and entire branches.
Probably Aleppo Pine blight

            From a distance this can look like borer damage. So far no one has discovered the cause of Aleppo Pine Blight or how to control it but it’s thought to be related to irrigation and not resulting from a pathogen or borers. Aleppo Pine Blight is so common in the Las Vegas Valley that if a pine tree has brown branches, it is an Aleppo Pine, not Mondell.
Eldarica or Mondell pine will get dieback in some branches as well but not as well documented as afghan (halapensis) pine blight

            My opinion of pine trees used for landscaping in the desert is mixed. I don’t think large pine trees should be planted here but I do understand their light shade value once they have become established and mature. What makes me hesitate is their removal I’m not sure if the shade they produce is worth the extensive deep watering needed to keep them healthy and upright against strong winds. In some lower elevations in the Valley, these large pine trees with extensive roots may have tapped into shallow groundwater which could help with irrigation and staying stable.
Japanese black pine has a distinctive look that attracts many landscape designers and architects. But in my opinion it is not a good choice for desert landscapes because of it doesn't seem to survive to maturity in our hot desert.

            Removing existing, mature pine trees from the property will increase the resident’s electrical costs used for cooling during the summer months. I would recommend that you transition your landscape to smaller, desert adapted trees that shade the south and west walls of your buildings and then possible pine removal. Once established, their shade will substitute for the pine trees and help reduce residential energy consumption.
Pine trees receiving adequate amounts of water develop a full canopy of needles and demonstrate good growth. But large mature trees need lots of water to stay healthy and deep irrigations to develop deep roots to withstand strong wind.

            It would be far better to plant smaller pines such as pinion and Italian stone pine if a pine tree is desired. Japanese black pine is sometimes recommended but look around. Do you see any older Japanese black pine in the valley? Many have been planted here. It doesn’t survive in the desert for any length of time so I would discourage planting Japanese black pine here.

3 comments:

  1. How do you tell if you have Aleppo or Mondell? Overall shape/density, bark, needles or cones? I assumed ours were Mondell.

    We have many on our (older) neighborhood and they do provide very good shade in the summer. A trade off to the almost year round clean up of needles. They are well established, I assumed the receive enough water by me as they look to be quite stable but I had not thought about them tapping into shallow groundwater.

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    1. When they are young they are very similar in many ways. They are both Christmas tree-like, they both have two needles joined together in a structure called a fascicle and the needles are about the same length. It is when they get older it can be easier to see the difference. Aleppo pine no longer develops a strong central leader...or Christmas tree shape while the Mondell does. After they get about 20 to 30 feet tall this central leader disappaears (most of the time) in halapensis (Aleppo) while the central leader stays in the center of the tree in Mondell (eldarica). But there can be alot of genetic variation in the trees and they can get confusing to tell the difference. Mondell pine needles are more "twisted" compared to halapensis in my opinion. That's why it is easier to look for aleppo pine blight sometimes. Sometimes they are easy to tell the difference and other times not so easy.

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  2. Aleppo, Japanese Black Pine and Italian Stone Pine have minds of their own when it comes to growing into interesting shapes. In Jan. 1975, we planted our first Aleppo pine, purchased as a 4'-tall Christmas tree in a 5-gallon bucket in December 1974. It is now over 50' tall with a trunk base circumference of about 11'. We had also planted Balm of Gilead Poplars because we love the ranch-look of cottonwoods, but eventually they contracted cytospora canker and had to be removed. Over time, we replaced them and added a total of 15 Allepos on the landscaped portion of our 2-1/2 acre property, along with 1 Italian stone pine, and the 3 types of local mesquites plus a couple of Chilean varieties to create a mesquite bosque. We also capitalized on the native acacia greggii and creosote brush already growing on the property. We decided against Mondales because their shapes are too formal for our more wilderness-look landscaping preferences. When the summer heat comes on, our pines often experience spotty dieback from heat stress; then we water a little more per water district regulations. We have no ground water, so irrigate with periodic fertilizer boosts. Our water bill runs around $350 during the hot months. We live on the far east side of Henderson, NV, on the rugged volcanic flank of the River Range, which usually runs 3-5 degrees warmer than the rest of the Las Vegas Valley. We have grass only in the root areas of the trees so both benefit and we can enjoy the meadow feel. And the wildlife loves the habitat we've created.

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