Q. I have two Mexican fan palms in my backyard that are 16-18 feet tall. One is 3 feet from a retaining wall and 6 feet from a pool. Another is 3 feet from the corner of my house which is on a slab. Do I need to worry about the roots damaging the wall, pool or slab? Way too close for palms to be planted to a wall. A. The short answer is you should be concerned anytime something that can get large is growing close to anything that can be damaged. The good news is that palm roots don’t typically damage walls, swimming pools and concrete slabs as much as other types of tree roots. But they can cause damage.             Palms in general are not a good choice around pools but Mexican fan palms get huge and should never be planted close to structures. Smaller palms, such as windmill and Mediterranean fan palm, would be a better choice. The closest large fan palms should be planted to walls, swimming pools and house slabs are perhaps 10 feet away. Palms look beautiful near a pool but they can cause problems and very messy when they drop seed.             There are a couple of options if you don’t want to remove these palms. One is installing a root barrier so that palm roots are deflected away from structures that could be damaged. Root barriers are installed and extend about 30 inches deep or more and reside slightly above soil level.             The second option is to use water for directing root growth. In deserts soils are normally dry due to a lack of rain. Tree roots grow where water is available. By placing irrigation water away from walls, cool decking or a house foundation we can direct tree root growth away from these potential problem areas.             Water does not need to be applied evenly under plant canopies. I recommend keeping water 2 – 3 feet away from these potential problem areas.

Q. My Italian cypress started to lose their color and then die. Upon inspection of the trunk, I saw borers in them. Borers seemed to take place within two months or so and killed a few mature trees. I treated them with Bayer Tree and Shrub Insect Control but wanted to know if there is anything else I can do to help save them. Borer damage found in Italian cypress trunk Bora damage found in another Italian cypress trunk Suspected board damage found in Italian Cypress A. Damage from borers or boring insects is typically a slower progression than a couple of months unless the plants are small. You are right, the progression in many plants is a change in color from a vibrant green to a dull, gray green color as the limb and leaves are dying from a lack of water.             My guess is borer damage to your trees started before this year. Internal damage to the trunk from borers can be present for several years before enough damage has accumulated to result in the death of older trees. If trees are growing vigorously, they can recover from light borer damage on an annual basis.             This color change due to damage starts in midsummer when air temperatures begin to heat up and plants require more water. Damage from boring insects begins in mid-spring (March) but get progressively more intense as these insects become larger and more voracious feeders.  By midsummer (June and later) internal damage to limbs and the trunk can be extensive, unrecoverable by the plant, and the supply of water from the roots is cut off. Homeowners have this product available for borer control containing Imidacloprid in the active ingredients. It comes in other names as well. It is always best to check the active ingredients to make sure. Apply it late spring after any flowering has occured to avaid possible problems with honeybees. This chemical has been implicated, not proven, in colony collapse of honeybees. The safest way to apply it in our environment is a soil drench. Always read the label before applying any chemical.             You chose the correct insecticide to use but it was probably applied too late. The best time to control boring insects with these types of insecticides is in mid spring when they first become active.             Consider using pesticides as a last resort because they can be a bit like “whack-a-mole” and contribute to other pest problems. Death of boring insects can happen in a few days when systemic insecticides are applied as a liquid drench to the soil.

Q. I have a ‘Green Gage’ plum tree that is 18 years old and produces plenty of plums each year. In August I saw sap coming out of one branch and along the trunk in several places.  Last week the bark started to separate and it looks like the trunk is starting to split. The leaves on that limb are starting to die. This side of the tree receives the west sun. All the other branches on the tree appear to be fine. A. Green Gauge is a good plum for our desert climate and 18 is not old for a plum tree. Plums can be “sappy” compared to other fruit trees but from your description it sure sounds like borers. You won’t hurt anything, but I would take a very sharp knife that has been sanitized and start actively looking for borers.             It is possible to remove the outer layer of bark covering the trunk and limbs and reveal the immature form of this insect, called the larva, causing the damage. Once exposed like this, it will die.             Expose all the damage caused by borers down to healthy wood. Leave this exposed area open for healing.  I would say that about 80% of the time this is an effective way to remove the borer and allow the limb to recover. What I Would Do I would first remove some bark on top of the area where I think borers might be residing. Hold the sharp knife nearly flat and push the blade away from you to remove the bark. After removal, inspect the wood to see if it is alive or dead. If it is alive, stop and don’t do anything more. If it is dead, remove all of this dead bark until you see bark that is alive. If you find evidence of borers, try to find them in this dead area and remove them. If the borer damage is extensive it might require removal of the limb or branch. Do not paint this area but let it heal in the open air. Using a sharp, sanitized knife to remove the bark that surrounds a borer infested limb. Removal of the dead wood caused by borers Successful removal of borers the previous year and the tree showing signs of healing.

Q. What should I do now with my 14-year-old, damaged African sumac? I think it had borers as you mentioned in a previous column, but the tree top is lush and green and showing no dieback of the limbs. A. Many older trees damaged by borers show only subtle, outward signs of damage. Early borer damage is difficult to see. It isn’t until damage is extensive, usually from attacks every year, does it become obvious to the casual observer because of limb dieback. This is a Purple Robe locust but it developed sunburn on the side facing the sun and this damaged area was followed up by an attack of borers.              I can see in the picture you sent that the borer damage to the trunk is healing. Encourage this type of healing with regular watering coupled with fertilizer applications twice a year. If it hasn’t been fertilized during the past 12 months, make an application when temperatures cool off a bit.             The best time to see “hidden damage” in the spring done by borers is immediately after a good rain. Damage to trees due to borers is expressed through the wet trunk or limbs as a reddish, jellylike ooze. If not seen right away, this “jelly” dries in a day or two leaving reddish crystals behind. Sap can sometimes be seen from trees attacked by boring insects. The best time to see this sap losing from the tree is immediately after rain.             It looks like a limb broke and ripped the trunk, perhaps as it fell. This could have been because of previous borer problems that weakened the tree at this location. The central core of all trees is dead and surrounded by a cylinder of living tissue that can heal these types of wounds. Sometimes trees can recover from an attack by boars if they are removed with a sharp knife or killed with a systemic insecticide.             This living cylinder can be thick or thin depending on tree health. When trees are healthy and vigorous, this living cylinder repairs damage quickly by “rolling over” damaged areas as seen in your picture. Large areas can heal over in a couple seasons of growth if the tree is healthy.

Q. We have two Raywood ash trees that are loosing whole branches and more from either a systemic disease or insects. The trees are about 23 years old and well cared for. Damage starts at the terminus of the branches and soon involves the whole branch leaving the leaves a light tan color over the entire branch and limb.  We have used Bayer systemic pesticide topically over the area of irrigation. Ash tree planted  with rock surface mulch surrounding it and leaf scorch.. Probably too hot in this location and perhaps not enough water applied. A. Three possible problems exist for that tree; drought, borers and a disease called ash decline. It is not a good tree if it is surrounded by rock mulch. It is more of a “mesic” tree which means it is better off in a mixed landscape, or a part of the landscape, that has a mixture of higher water using plants. Drought Sometimes this tree is put in a part of the landscape surrounded by rock and water delivered from drip emitters. Rock surrounding this tree is not a good idea. As the tree gets bigger it needs more water. If more emitters are not added or more water provided during summer months it can become droughty and you will see dieback of limbs. Smooth bark of some trees can lead to sunscald. The orange discoloration on the trunk is light sunscald. It helps if ash is not planted in rock. Sunscald and borers The bark on the tree when it is young is fairly thin so it doesn’t do well with intense sunlight on the trunk for long periods of time. It can get sunburned fairly easily when in west or south exposures of intense sunlight particularly surrounded by rock on the surface of the soil. This frequently leads to borer problems in the sunscald areas of the trunk. You will see dieback of limbs and a loosening of the bark on the trunk on the West or South sides of the trunk. The area under this loosening is dead due to intense sunlight (sunscald) and this is wear the borers are typically seen. Bayer helps but the real problem is its location in the landscape. This is sunscald (sunburn) on the trunk of an ash tree. Most likely the trunk is dead on that side where sunscald occurs. This damage is thought to attract borers like the flatheaded apple tree borer which attacks many different plants. Ash  decline This is a disease that is common on many ash trees including Raywood. The damage resembles drought because the disease plugs the vessels inside the tree that carry water. The limbs begin dying and the tree dies a slow death over years. It is best to remove it if this is the case. What to do?  Look for damage to the trunk from sunscald and borers. If you see it then this could be the problem or part of a problem. Make sure the tree is getting enough water when it is watered. At 23 years old it should be getting 30 to 50 gallons each time it is watered. You can supplement water given to it by putting other plants that require water near it so they can share water. If you don’t see any improvement in the tree by giving it more water and you find no borers then it probably has ash decline and consider removing it. The link below is accurate info on this tree. Other info could be sales hype.

Q. My bottle tree trunk is turning somewhat of a burgundy color. I live in Las Vegas and they were planted just over a month ago. Some leaves are brown in full and some partially but overall seems alright minus the trunk having that reddish tone while the other 3 are greenish grey.  A. I get more questions about this tree than probably any other. It has been touted as a “desert tree”, but is it? Bottle trees are not really DESERT trees but more Mediterranean in their semi-arid agroclimatic origins. Think more like palms, olives, rosemary and even oleander. Discoloration of the limbs The “skin” or trunk and limb surfaces are photosynthetic (green) which means that they can manufacture its own energy besides 100% by the leaves as trees with dark brown limbs and trunk can. Some trees that have this quality can handle high light intensities that come with an open canopy. Sunburn on bottle tree limbs. Notice that sunburn happens on the upper limb surfaces exposed to direct sunlight. Unfortunately bottle tree of this type (Brachychiton populneus) doesn’t appear that it can. When the canopy opens up because of leaf drop or a thin canopy the upper sides of the limbs can “burn”. Frequently this may cause interference with the water transport to the leaves. But if at least half of the limb is unaffected, the tree should survive. Drought Even bottle trees can suffer from a lack of water. Watering every day can still result in drought IF the amount of water applied does not meet its need for water. A usual sign that a tree is not getting enough water is a thinning of  its canopy. Bottle trees can also drop leaves in midsummer,as reported by some homeowners in Phoenix. A bit unsettling when you don’t know what the leaf drop means. Drainage Bottle trees do well in lawns if the soil drains water well.  Young bottle tree growing in a lawn

Q. These are my sorry peaches harvested last Saturday. This is their third year, and they seem to develop to only this size. We fertilize them twice a year with vegetable spikes, and our in-ground system has Dr Bensons added 5 times per year. Any suggestions? A. Age of the Tree First of all, this is only a three-year-old tree! Give it a chance to grow up. The third year it is in the ground you should start expecting some fruit to be produced that you can eat. But not much. Most of the energy is going into making it bigger, not into production.  Think of a young child. Would you want an eight-year-old daughter to have children? Expect it to start into production this year to a very small degree and next year when it is really starting into production. Thin the Fruit This means remove fruit so that the remaining fruit gets larger. Think of it like this. If you are earning $20,000 a year, which is better for your family? Two children or 12 children? The answer is obvious.If you remove some of the fruit from the tree, the remaining fruit will get more of the water, nutrients and minerals sent from the leaves and the roots. This means the remaining fruit gets a larger share of what the tree can produce. Remove fruit so that there is the distance of a fist between the fruit. Do not grow them in clusters but space them along the branches in production. This may mean you could remove two thirds of all the fruit on a branch. Do this when the fruit is about the size of a thumbnail. Peaches before thinning Peaches after thinning Removal of fruit depends on its purpose after harvest and the variety. Do you want large fruit so that you have bragging rights or smaller fruit. If it’s for canning, sometimes large fruit is not the best idea but medium-sized is better. If it’s going to fresh market for eating then larger peach size is usually better. The more fruit removed, the larger will be the remaining fruit. Watering To reach their maximum size, don’t allow the soil to dry while fruit is developing its size. This means even amounts of soil moisture all the time it’s producing fruit.. A layer of 4 to 6 inches of woodchips helps to retain soil moisture and produces larger fruit.  4 to 6 inches of woodchip mulch helps conserve water and makes larger fruit. Don’t surround fruit trees with rock. Fertilizer Fertilizer alone will not make larger fruit. But if fertilizer is lacking it will affect fruit size.Fertilize at least once during the year of production. The best time is just before flowering. Fertilizer can be applied in many forms including compost, granular fertilizer and fertilizer stakes. Here fertilizer stakes are driven into the ground with a hammer near the drip emitters. Pruning Pruning peaches and nectarines is different from pruning most other tree fruit. Fruit is produced laterally or along the edges of last year’s growth. You want about 18 – 24 inches of new growth produced each year. Half of all of this growth is removed during pruning. Leave too much last year’s growth and sending becomes a nightmare. Remove too much of last year’s growth and food production will be small but they remaining fruit large. This is something you have to play with until you get it right. It will vary with each of the different varieties. Six-year-old Peach tree showing its open center form after pruning. Fruit will be produced on the reddish growth from last year. This growth should be distributed throughout the canopy and be about 18 – 24 inches long. The next step after flowering is fruit thinning when fruit is thumbnail sized.

Q. My daughter in Illinois asked me about this. Two different kinds of leaves growing on the same tree. This picture was sent to me but I think it was borrowed from this blog,https://earthshinenaturewatch.blogspot.com/2015/08/polymorphic-leaves.html  A.Academically these are called polymorphic leaves, two different shapes of leaves growing on the same plant. Plants are much more variable than animals. Here is a good example. You can read an at academic treatment about Polymorphism by following the link here. The word polymorphism is a common concept in biology. The term polymorphic is applied to animals as well as plants when there are different forms of the same animal or plant part. So in the case of polymorphism in trees we use the term “polymorphic leaves”, or “polymorphic flowers” for instance because these are found on the same plant. Polymorphic leaves are very common on mulberries where this photo is from but it can also be found in the East Coast of the United States on Sassafras. It can be applied to biochemicals and the term also used in genetics. https://www.actahort.org/books/1173/1173_9.htm We can only guess why there are different forms of leaves in mulberry. In some herbs, polymorphism is thought to be related to soil moisture content. http://forestandrange.org/new_wetlands/plant_adaptations_polymorphic.htm In Red and white mulberries, some people think it has to do with access to light were full leaves are produced in the early and leaves with lobes or cuts in them are produced later in the sunlight above shade leaves. It is thought that this is an evolutionary adaptation that allows more light to reach the lower leaves. Of course these are just guesses about why plants do the things they do. Otherwise, just enjoy their diversity. So if you want to sound educated and knowledgeable throw around the term “polymorphic” so people will be impressed.

When: Saturday, October 13 from 9 am to 1 pm. Where: 1897 North Moapa Valley Blvd., Logandale, Nevada Space is limited and so are tickets due to the size of the classroom.. My presentation is in conjunction with the the University of Nevada Cooperative Extension and the 23rd annual Pomegranate Festival , this year on November 2 and 3, and held each year. For more information call Nevada Cooperative Extension in Logandale, Nevada, at 702-397-2604, Extension 0. Or email [email protected] Free tickets for the event are available at Eventbrite but space is limited. Robert Ll. Morris is a Horticulturist and Associate Professor Emeritus from the University of Nevada who has been working with food and water issues in the arid West and around the world for the past 40 years. Robert spearheaded the University Orchard in North Las Vegas growing a wide range of fruits, vegetables and herbs and pioneered the marketing of locally grown food by small-scale producers in the Las Vegas Valley. He is co-author of two publications published by the University of California and CAST (Council for Agricultural Science and Technology), authored over 35 research articles, over 1,000 trade journal articles, a regular columnist with the Las Vegas Review Journal newspaper, Consulting Editor for HortScience, a flagship publication for the American Society for Horticultural Science. Visit his blog at Xtremehorticulture.blogspot.com. Questions about the class can be directed to his email at [email protected]. 

Q. I have 19 mature, healthy Mexican fan palms pruned every year after flowering. This year they were pruned on June 13 but after three weeks one suddenly died, and another died two weeks later. I used the same pruning crew for 5 years with no problems. I removed about 250 square feet of turf from in front of the trees last year with no other significant changes to their irrigation or fertilization regimen.  A. They died because the central bud at the top of the tree died. I can’t tell you exactly the reason why they died without climbing to the top, but I can give you some possibilities. Perhaps you can sort it out from there.             I don’t think this is an irrigation issue because it happened too rapidly. It is most likely a disease problem. I would guess it is either from using unsanitary pruning tools or too many palm fronds were removed. Sanitation a Problem             Pruning tools must be sanitized to prevent the transmission of disease from one tree to another. Diseases are passed from tree to tree or even limb to limb by using unsanitary tools. At a bare minimum, pruning tools should be sanitized between job sites. Ideally, they should be sanitized between trees, particularly when pruning “sick” trees. 70% ethyl alcohol is probably the best sanitizers but a good cleanser will work             I like to ask, “Would you let a doctor use a needle or scalpel just used on another patient?” Pruning plants is similar. Disease transmission is less likely between plants that are not similar but when plants are similar, all palms for instance, more care should be used.             Sanitation of pruning tools can be simple; from wiping the tools clean and applying alcohol for Pine Sol or even heating the blade with a Bic butane lighter. Too Many Fronds Removed             The second possibility is damage to the central bud by removing too many fronds protecting it. The central bud of a palm tree is located at the very top of the trunk. It is surrounded by palm fronds that emerged from the bud earlier in the season. Removing too many fronds can leave the central bud exposed to intense sunlight and brutal wind, the bud dies and the tree collapses.             The newest fronds are clustered around the bud while older fronds are lower and removed as they become brown or drop below horizontal. Older fronds provide no protection to the bud. Horticulturists all agree that excessive removal of palm fronds can lead to palm problems.             Excessive removal occurs when fronds are removed that previously played a role in shading it from intense sunlight or protection from other types of damage. If too many fronds are removed, protection of the bud is jeopardized. Too many fronds removed? Duh!!!! This is exaggerated but it was done! Leave a half-moon of fronds when you are done.             How many should remain after pruning? Enough to protect the bud and provide energy through the leaves for vigorous new growth. Remaining fronds should occupy an upside down half-circle or 180°.