Xtremehorticulture

Xtremehorticulture of the Desert

Acacia Damaged by Low Temperatures and How to Remove Limbs

2 Comments / pruning, removing large limbs, shoulder /

Q. Any advice on Acacia trees would be great.  These trees took a hit when the temps dropped to the 20’s in December.  I see new growth, but mostly on the suckers.  Should I leave the suckers there or remove them? What is the best thing to do to help these trees recover? A. This is more complicated. First you will remove any wood you know is dead. By now (June), any part of the tree which is still alive should have thrown out some growth. Remove any limbs that are dead (no growth coming from them) by cutting at point of attachment to another limb or the trunk.  You should not leave any stubs when you are done.             If the limb is large and heavy, you should remove it by either removing sections of the limb at a time that are manageable or use a technique that we sometimes call the 1-2-3 method. This is demonstrated pretty good on removing a limb on wikihow. Here is our sequence of cuts at the Orchard. Cut number 1 is made upward about a foot from where the final cut will be made. The second cut is made downward a few inches away and to the outside of the first upward cut. The weight of the large limb causes the limb to begin splitting when it falls. The split occurs from the outside second cut to the upward first cut. The prevents the limb from splitting down the side of the branch and into the trunk. This is a look at the limb that has split from the branch and now lies on the ground. The third and final cut in the 1-2-3 limb removal sequence is made at the proper distance from the trunk. This leaves the trunk/limb “shoulder” in place and finds the balance between the smallest cut possible and not leaving a stub. The cut is left to heal on its own and no coating or sealer is used.   This is a different tree but gives you an idea of what the “shoulder” looks like and where it might be located on a much smaller limb.  Next, remove any broken branches. They will not repair themselves. Remove any wild or “sucker” growth. This type of growth usually has weak attachment to the trunk and not support itself in years to come. Remove any growth coming from the trunk that is not high enough in the future.             This growth will not get any higher and as it gets bigger will “sag” or bend downward perhaps into places where you can bang your head. Remove these by making a “flesh cut” in other words remove it all and don’t leave a stub.             Finally thin out the remaining branches so that any dead wood is removed (again by making “thinning cut” which is the same as in the third sentence, removing it at a point of attachment without leaving a stub.) Try to have the remaining branches going in different directions to help balance the crown visually.             I hope this helps. By the way, I would do any major limb removal next early spring after the worst temperatures have passed. Minor cuts (with a hand shears) can be done any time.

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Suckering of Citrus Due to Cold Damage

Leave a Comment / cold damage to orange, lemon, lime, removing suckers /

Q. The low temperatures affected our citrus trees from last year.  Most of my new growth is on the suckers.  Should I remove them?  Or just let the tree be? A. If you look at the trunk of the tree you should see a bend in the trunk or “dogleg” where the top was budded or grafted on to the rootstock. I doubt if it is on its own roots which would mean you would see no bend or dogleg. Example of a “dogleg” where a fruit tree (in this case not citrus) was budded previously.             Anything coming from or below this bend should be removed and kept off. Whenever you see any type of growth at all from these spots it should be removed. If you let this growth develop it will rob growth from the part of the tree you want to keep and eventually dwarf or kill the good part of the tree.             Next you want to allow the lowest branches to develop from the trunk at a height you want these branches to remain. The distance these lowest branches are now will be the height they will be in ten years from now. I did not have a pic from the reader and this is not citrus but this will give you an idea of what suckers that are coming from the rootstock might look like. The suckers are dark brown. The trunk is whitish due to painting the trunk two years prior. These suckers need to be removed by digging the soil away from the trunk and removing them as close to the trunk as possible. Replace the soil after the wound from cutting has begun healing, normally at least 48 hours.             If these are too low then move up the trunk to a place where you want the lowest limbs to develop. Remove any of these unwanted lower limbs completely from the trunk by cutting them as close to the trunk as possible.             You can do this now if you want or you can wait until next January or February if there is fruit on them. I am not sure which citrus you have but if it is lemon they should probably be harvested in December.             Try to find limbs to keep which are coming from the trunk going in different directions. Hopefully you will find one limb going north, one south, one east and one west (I think you get what I mean by going in different directions as this will give the tree “balance” and reduce shading of itself).             On the limbs coming from the trunk, remove shoots going straight up or straight down. This leaves shoots that spread out in a fan (horizontally or laterally) but remove shoots that are growing up or down. This allows for better light penetration inside the tree and helps distribute fruit production throughout the canopy rather than just on the perimeter. I hope this helps.

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Nematodes Permanent Garden Problem

2 Comments / balls on roots, knots, nematode, root knot, swelling, tomato /

Q. Are these nematodes on my tomato roots in the picture I sent to you? Picture sent from reader A. Yes, you have them. Once you have nematodes they are a permanent pest in your vegetable garden. Your future with them is in managing their new home but you will never be rid of them.             In the past, soil fumigants were available that would dramatically reduce their numbers and easily make them manageable. These soil fumigants are no longer available to homeowners and highly restricted even for commercial applicators due to their potential in damaging the environment. Root knot nematode on tomato             There are multiple approaches in managing nematodes. One way is to exclude them. You can do this by growing vegetables that are highly susceptible in pots or containers. If the pots or containers are in direct contact with the soil containing nematodes, the nematodes will move into the container eventually.             You can impede this by putting down a layer of coarse gravel on top of the soil and putting the containers on top of the gravel.             If you want to grow in the ground with nematodes then heavily enriching the soil with organic material such as high-quality compost will help to deter them. Keeping the soil as healthy as possible is a great deterrent. Nematodes do not seem to like heavily enriched soils.             Another deterrent is to select plants that nematodes do not seem to like very much. There are some vegetables somewhat resistant to nematodes but it is quite lengthy. I will post this list on my blog but a few of them include broccoli, cauliflower, chives, and many mustards.             There are other plants which nematodes really like a lot but plant breeding has produced some varieties which are resistant to nematodes and a few plant diseases. These varieties have capital letters such as V,F,T,N after their names which designate their resistance. The capital N in this case designates nematodes.             Another method is growing marigolds in the vegetable plot. The most effective way is to grow a solid stand of marigolds for at least 2 to 3 months in the planting bed. Turn these marigolds under the soil so that they decompose. Then plant your vegetables.             Some people grow them on the borders of the vegetable plot but it is not as effective as growing a solid stand and turning them under.             There are some products available such as Clandosan which gives some benefit and could also be incorporated into the soil.

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Large Boxed Tree Needs Extra Help

Leave a Comment / ball and burlap, how to, large trees, tree staking /

Q. Should a newly planted 36″ boxed purple robe black locust tree have it’s nursery stake removed? I sent you a picture of it. Readers Purple Robe Black Locust staked. A. Larger trees need their roots stabilized for one to two growing seasons and then the stakes removed. In your case the tree has poor trunk strength since the trunk has no taper to it and the trunk will snap in high winds.             Immobilize the roots by re-staking the tree. Let side branches develop along the trunk to improve trunk taper and strengthen it. Normally, a tree with good trunk taper can have its stakes removed after one to two growing seasons. A tree with poor trunk taper will require a longer period of staking to strengthen the trunk AND give it solid rooting into the surrounding soil.             Allowing side branches to grow along the trunk helps promote taper in the trunk reducing its need for staking after one season.             Ideally, the tree should have small stems growing from the trunk covered in leaves, removing them only when they reach about pencil diameter. This increases stem taper, reduces the possibility of shear or snapping in high winds.              Trees also need to “sway” in the wind. This swaying or movement of the trunk from side to side also helps to develop taper in the trunk. But the roots of the tree need to hold the trunk in place at the bottom.             This tree will need to be staked for awhile to keep the trunk from snapping. Probably at least one season. I would probably restake the tree with either two or three stakes to support the trunk and keep it from bending to the point where it could snap and immobilize the roots. Large trees usually need stakes to support the trunk. The stakes should be driven deep enough so that they are in solid soil. The support from the stakes should be low enough to allow the top of the tree to move but keep the rootball from moving.             Two methods used for re-staking include a two to three stake method with the stakes driven into the solid soil beneath the rootball. The other way is to use guy wires to stabilize the tree. I supplied pictures that I will also post on my blog.             This next year let small branches grow from the trunk if they develop. These will increase the strength of the trunk and help reduce sun damage to it as well. Remove older branches from the trunk when they get larger than a pencil in diameter. Cut them off flush with the trunk. Do not use pruning paint.

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Container Plants Difficult to Manage for Snowbirds

Leave a Comment / container planting, snowbirds, vacation /

Q. We winter in Boulder City in a condo RV park. Three years ago we planted a rose bush that did wonderfully well until it died last summer. The pot gets plenty of water from a drip hose. We would like to put something in the pot more capable of surviving the extremes of the high desert. I would be happy with anything that will flower or fruit when we are here in the winter and is OK with being abandoned for six months.  A. It will be very, very difficult to grow much of anything in a pot if it is not attended to. You might be better off putting something there that will not die and, while you are here, growing something that you can dispose of when you leave such as an annual.             The other possibility is to have someone care for your plants while you are gone. The summers here are brutal on plants as you know. We get fluctuations in our weather that are very unpredictable.             If you insist on growing something in a container then double pot your container so that the container you are growing in is surrounded by another container or object that shades the outside of the inner container.             Surface temperatures of containers that receive direct sunlight in late spring and summer will produce temperatures inside the container that will kill plant roots. Double potting a container with a larger container with gravel in the bottom and just airspace on the sides will help insulate the soil inside the container.             Surface temperatures of a container will easily rise above 165F in direct sunlight. This heat transfers to the soil and cooks the roots on the side exposed.             Another possibility will be to grow cacti in containers and watering it no more than about once every two weeks. Once a week if the container is small. Make sure the soil for the cactus drains readily. The container should still be double potted.

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Oleander Shows Signs of Winter Dieback

1 Comment / dead leaves, dead stems, lowest temperature, oleander dieback /

            Reports from the weather station at the UNCE Orchard in North Las Vegas put the low temperatures on December 6 and 10 at 20F with daytime highs around the same as the inside of a refrigerator. I am sure this caused some damage to plants in that area. I posted the weather report on my blog for those interested. Q. I believe I messed up with my one year old oleanders. I covered them with old cotton bed sheets and then plastic bags thinking it would protect them. When I uncovered them, the sheets were frozen with what I assume was condensation caused by the plastic bags. I’m hoping they survive as much of the lower foliage is still green and soft. What is my next option?   Freeze damage to oleander in north las vegas Freeze damage to hedged oleander and new spring growth A. I don’t think you made a mistake. They just froze, that’s all. 9 times out of 10 they will come back in the spring. In fact the freezing bed sheet gave the oleander a few extra degrees of warmth.             Wait until spring and new growth before making any decisions. It is possible the oleander just got some leaf and the stem death with some of the stems still alive. You will not know until it starts growing again but I don’t think you lost them.             The degree of damage to a plant will depend on the plant itself, its variety and how it was cared for, weather prior to the freeze, landscape microclimate, the minimum temperature reached and the duration of that temperature. It can be really difficult to predict the degree of damage done for quite some time.             There may still be some cold coming later in the winter. Sometimes freezing temperatures in February, when plants are preparing for spring, can be much worse than the same temperatures in December or January.             Don’t prune them back just yet. Be patient and see what spring brings.

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Ants Farming Aphids on Pyracantha

1 Comment / ants, firethorn, green bugs, plant lice, pyracantha, sticky sap /

Q. We have a couple pyracantha bushes. We noticed this past summer some small, pen point sized, bright green bugs on the end of the branches. A day or two later I noticed ants in those same places but couldn’t tell if they were eating the bugs or not. Please advise if we need to do something.   Pyracantha, sometimes called firethorn,, with its red berries.Some have orange, yellow and off-red. A. From the sound of it the bush had aphids, sometimes called plant lice, but summer is not the usual time that aphids appear. Aphids normally appear with new growth in the spring and disappear when it gets hot.             Ants are attracted to aphids because the aphids release sugary honeydew when they’re feeding on the pyracantha leaves. Leaf cupping on plums due to aphid feeding in the spring.             Ants “farm” the aphids, take this honeydew excretion and use it. So you may see ants traveling up and down the pyracantha gathering and transporting honeydew to their nest in the soil. Ants may even move the aphids around to new locations to expand their “herd”.             It’s not a big problem if these are just aphids. The aphids will cause some stickiness on the leaves and may cause leaves to fall from the plant if the feeding becomes heavy. But that time of year I would not expect them to be a big problem. Ants herding aphids for their honeydew             If the problems is excessive the easiest thing to do is mix some soap and water, about as much as you would use when you would wash your dishes. Put it in a spray bottle and spray the soapy mixture directly on these green bugs, usually on the underside of the leaves.             You will probably have to do this every couple of days since soap and water does not leave any poisonous residue on the leaf surface and these spots will repopulate quickly after the spraying is done.             If you want more permanent control then you can use a traditional insecticide that has a label listing ornamental plants and aphid control. You can also treat the ant nest in the soil. Pouring boiling water on the ant hill will give some temporary organic control of the ants.

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Tipu Sensitive to Winter Cold in the Las Vegas Desert

1 Comment / dieback, tipu, tipuana, tree selection las vegas, winter damage, winter kill /

Q. We purchased 11 Tipu trees in March of 2012.  We purchased these trees because they were recommended as fast growing trees for our property. Three of the 11 trees we planted died during the winter of 2012-13 and only growing “suckers” around the base of the trunks.  An arborist told us the trees were “toast” and recommended we might leave the suckers to regrow into a tree rather than remove them. Is there anything else we can do to help these trees or do you think they are a lost cause?  Tipu showing regrowth from the base after winter kill due to low temperatures. A. As you have already found out, this tree will freeze in our climate. This is what I believe killed the tops of your trees this past winter. According to Arizona State University it is hardy down to about 25°F. Temperatures below this cause winter leaf drop first followed by branch and trunk death as temperatures drop further.             What you are seeing now is resprouting of the tree from the base which was protected from freezing temperatures by the soil. If the temperature had dropped even further you might have lost the entire tree with no regrowth from suckers.             The arborist was right. You could select one of the stronger suckers and remove the rest. If you want a multi-trunked tree then leave three to five. These nurtured suckers will grow up to be a new tree that will promptly freeze to the ground again when temperatures drop to that 20ish F range.             I am not in favor of growing this tree here and I will tell you why. This tree is originally from South America where it can reach heights of 100 feet with a 60 foot spread. In our harsh, desert climate it won’t get that tall but might reach 40 feet or so.             In the wetter parts of California it has been used in water conservation landscapes. It is not a desert plant and should not be considered low water use and in the same category as acacias for instance. These trees should be considered moderate in their water use, similar to ash of a similar size.             In some places they are considered invasive and their root systems destructive. This should not be the case here if you plant them several feet from walls, sidewalks, driveways and foundations. Plus, you should water them infrequently, not with shallow frequent irrigations and irrigate on sides away from structures to less damaging root growth.             A lot of people in the warmer Phoenix area like this tree. There are a few who don’t like the litter it produces and fear it’s destructive potential. In a nutshell, because of its lack of cold hardiness, I do not believe it is suitable for the cooler climate of the Las Vegas Valley.

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Bring Back Queen Palm from the Dead

Leave a Comment / cold, heat, iron, irrigation, queen palm, summer dieback, yellow /

Q. During the excessive hot spell in July our irrigation failed while we were out of town. As a result, one of our queen palms lost all its branches. In spite of subsequent life support, it does not appear to be coming back. Is that too much to hope for? Is there anything we can do to help it recover or should we just mourn its passing? Queen palms dead during first winter planted (1989/90) at local casino. Admittedly temperatures hit a 50 year low. A. Queen palms can handle heat but they struggle with extreme cold (25F) and hot, dry winds. In short, among the approximately ten palms we can grow here, they are not among the “chosen ones”. However, if these plants are water stressed or planted under poor soil conditions then they will not tolerate heat very well either.  Queen palm fronds from central bud yellowing during new growth             The only places here where I have seen decent, older queen palms has been in areas protected from wind, the soil prepared adequately with amendments and the use of organic surface mulches.  Queen palm with yellowing foliage after planting in rock mulch. Probably iron chlorosis and poor soil enrichment at planting.             Once they are stressed and water is withheld, they will suffer greatly. They need adequate soil preparation at the time of planting, good drainage, protection from winds and low temperatures, an annual fertilization program and organic surface mulches.

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Pohutukawa Tree: Maybe a Kiwi Can Help Out

1 Comment / christmas, metrosideros excelsa, new zealand tree, red flowers /

Q. I would like to purchase a Metrosideros excelsa ( Pohutukawa) Tree and would like to know if it can survive Las Vegas hot climate. Picture of Pohutukawa tree sent to me by reader. A. Well you have me on this one. This is the first question I have ever had on this tree. I had heard of it but never had read anything much about it and of course have no experience with it. So, all I can do is what I have done which is read as much as I could find out about this tree and how it has handled similar climates.  Maybe if there are any Kiwis reading this post from down under they can respond. But keep in mind the Las Vegas climate is DESERT, with summer temperatures reaching over 45C (115F+) very low humidity and soils that I would describe as “moon dirt”, structureless, high in salinity (but manageable most of the time) and winter lows of -8C ( below 20F for brief periods of time in the morning hours). First, there are no postings I could find from anyone in a desert climate trying this tree. We do know that it will handle temperatures down to about 20F ish…, it can be found growing naturally on very rocky soils in New Zealand, usually close to the ocean. So in the US it has been grown successfully along the California coast, mostly in northern California and up into the Pacific Northwest. So know this about the tree and some other things stuck in my head from my reading I would say the following. It is worth a try provided you can plant it in a place out of dry, desert wind, a bit protected from cold such as closer to town and really improve the soil at planting time. What I would expect from this tree would be that it will have some problems. Namely, it will probably never look as good as it does in coastal climates. The leaves will probably have a tendency to scorch and damaged by wind. It may also tend to get yellow due to a lack of available iron so I would be giving it an iron fertilizer annually. It will not like a desert landscape so if it can be planted in a lawn you will be better off. Expect it to dieback during some winters with very low temperatures. The degree of dieback will depend on the part of the valley you live and how well it is protected from winter cold and winter winds. Expect with these diebacks that it will tend to want to be more shrubby than tree-like. It can be easily started from seed. That is my best shot at it.

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