Xtremehorticulture

Xtremehorticulture of the Desert

Star Jasmine Problems Mostly Soil, Mulch and Cold Related

14 Comments / bronzing of leaves, Las Vegas, leaf drop, Mohave Desert, Mojave Desert, nevada, scorching leaves, yellow leaves /

Q. What can I do to correct all the issues afflicting the star jasmine this winter? Problems with star jasmine. Most of these are caused by poor soil conditions and winter cold. Perhaps it might be not watered with enough water. A. The easiest is to not plant it. Hard to say exactly but generally I would call the problems in general, stress. The stress could have come from freezing temperatures, lack of water, poor soil or poor soil amendments such as high salts and lack of organic matter. Great place to put a star jasmine for aroma and welcome greetings to visitors.             The plant is some eastern and southern China and which means it is not from a desert and not really a desert plant. We have to adjust everything around it for that reason. It is not going to like desert soils or rock mulch for that reason. Star jasmine used as groundcover in rock mulch. I guarantee that plant HATES it there. Developed iron chlorosis due to rock mulch and poor soils.             Soils must have lots of rich soil amendment (compost) and it will really appreciate wood mulches. It does well as a groundcover but I think it is best as a north or east-facing trellised vine. Particularly near a window that can be opened in the Spring. When star jasmine is growing well and in good health the leaves should be a vibrant green.             The flowers are very fragrant so it should be planted in locations where the fragrance can be appreciated. It is an old-fashioned plant. Southerners might know it by the name “Confederate jasmine”.             It handles the cold winters well if it is not in rock mulch. At real low temperatures the leaves may get that bronzy, yellowish color that plant leaves can get when it is cold but will handle temperatures to 10F pretty easily. Citrus leaves will bronze in winter the same way.             Flood the soil with water to remove possible salts and let it drain. Add compost to the soil surface around it and water it in. Replace rock mulch with wood mulch but keep the mulch away from the stems to prevent collar rot.             Fertilize in the spring with a good quality fertilizer for flowering plants like roses. Shear off the old growth and let it regrow in good health. One time I had to cut a star jasmine used as a vine way back to get it to flower for me in a north exposure.

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Things To Do With Fruit Trees Now

Leave a Comment / Las Vegas, Mohave Desert, Mojave Desert, nevada, peach calendar, what to do with fruit trees /

While pruning the last couple of days I saw some things  to do that I wanted to bring to your attention. I saw an increase in borer damage to even small limbs now. I think that is because of a lack of borer removal and not whitewashing. It is also possible it could be due to lack of water if they have gone through drought. Borer damage to peach I saw peach twig borer damage from last year in small shoots that were still attached to the tree. That means populations were very high and not controlled. Peach twig borer damage from last year on young growth. The twig borer burrows into soft, young stems causing the stems to dieback. Populations of this moth build during the summer months after with each successive generation. When fruit is out and getting soft they will attack soft fruit causing wormy peaches and almonds.  I will cover these more in detail as the season progresses.  Nectarines need to be sprayed immediately after petal fall for thrips. Use spinosad in rotation with other labeled sprays. Things to be done at the orchard: ·     Fertilize all trees and vines ·     Borer removal with knives. Eliminate loose bark down to healthy wood. ·     Whitewash upper sides of scaffold limbs for borer prevention ·     Purchase pheremone traps and pheremones for peach twig borer (peaches, nectarines and almonds) and codling moth (apples and pears). Set one trap each for monitoring in early April. As soon as moths are caught, set two more traps in the orchard for trapping. This has worked on codling moth in the past. ·    Bt sprays need to be timed for the first wave of peach twig borer. This will reduce the numbers in future generations. If you don’t start spraying after the first flight the population will blossom into some heavy damage including infesting the fruit later. ·    Nectarines need to be sprayed with Spinosad immediately after petal fall and follow up sprays are needed for scar-free fruit. ·    Bubblers and drip emitters need to be checked for plugging monthly.

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Not Too Late to Trim and Fertilize Lantana

Leave a Comment / camara, desert, how to prune, lantana, Las Vegas, Mohave Desert, Mojave Desert, montevideo, nevada, pruning, when to prune /

We generally grow two types of lantana in the landscapes in southern Nevada; the purple one and the one that is multi-colored, usually with some yellow and rose or pink flowers. Both are handled about the same way in watering, pruning and fertilizing. Multi-colored lantana (L. camara) but at this point only showing just yellow flowers but can change to orange or pink later. The flowers can vary in color.   This is the purple species (L. montevidensis) sometimes called trailing lantana or weeping lantana. It was collected and propagated for sale near Montevideo, Uruguay, hence the Latin name. Come take a tour of Montevideo and see where L. montevidensis came from Both of these plants came out of South America, around Bolivia, Peru and Uruguay area where it does not freeze where it is a widespread native. Not truly a ‘desert’ plant but tolerates dry or semiarid environments near the coastline. It is now widely planted all over the tropics and subtropical parts of the world where it does not freeze back in the winter. It showed some promise in the desert and arid parts of the southern US and now is quite common. Some people would say now it is over planted but it still gives a nice show of color in the summer with little care. It will freeze back here and rebound in the spring. Pruning or Cutting the Back. The purple lantana is common now and I get alot of questions about how far back you can trim them. Take a close look at this picture. I took it a short time back when I first saw green coming from a winter pruned shrub.They can get kind of lanky and loose some eye appeal as well as die back in our colder climate so many people cut them back in the winter. It is always a good idea to wait until the coldest part of the winter has past before you cut them back or the may freeze back further. Lantana pruned back. This is fine.   See how the new growth is coming from the “joints” or “nobs” on the stems? These are nodes where buds or stems were located. They are places that contain the potential for new growth. Cut them back leaving a couple of these or more between your cut and the ground. Then they will have these spots to generate some new growth for this season. Fertilizer. Just before the really start pushing some new growth (late January or even into Februray), fertilize them. Liquid fertilizers like Miracle Gro or Peters do a great job as long as you apply enough water when the plant is growing. Less expensive fertilizers will work as well but just make sure you use one that is used for flowers or tomatoes or other flowering plants. You can apply the fertilizer dissolved or diluted in water in a plastic bucket and pour it slowly around the plants or you can apply it dry just under the drip emitters. One application is normally enough until next year. Never apply it after about August or you could affect how much winter dieback you get. It normally does not need any iron added but doesn’t hurt either. Hmmm…. none say to use on Lantana! What do I do now? You like the flowers. Promote the flowers. Use a fertilizer that promotes flowers. So you can use tomato fertilizer or rose fertilizer as a substitute. What’s wrong with this lantana? Just TLC; water, soil improvement and fertilizer. AND it was planted too close to the curb. It should be back in about three feet. It’s growing toward the south where there is more light and probably the one emitter it has.

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Please Dont Prune Your Palo Verde LIke This

6 Comments / desert, Las Vegas, Mohave Desert, Mojave Desert, nevada, pruning palo verde, topping, trees /

I was dumbfounded. I saw it from the bus. I take the bus to the Orchard in North Las Vegas up Decatur when I go there to teach or just volunteer. I got off the bus and walked over to this tree because it was sooo obvious. What in the world was going through this person’s head? A beautiful tree and its form butchered. The tree could have been pruned with fewer cuts and not so much to clean up after you were done. This will take years to correct by a competent, skilled tree worker. Some say “arborist” but there are skilled arborists and unskilled arborists. There are skilled tree workers and unskilled tree workers. There are skilled gardeners and unskilled gardeners. Some of the best tree work I have seen was done by an indvidual (now passed) many years ago who had no training (at the time) but was sensitive to the look and needs of the tree. He went on to become an excellent arborist. (Steve Hines where are you?) Heading cuts. The cuts made at the very top are what I call “heading cuts”. They were made anywhere  along the length of a branch. When this is done we call this “topping” a tree. This is not a good idea for many reasons. From the looks of all that growth at the top, the tree has been topped at least one other previous year. Pruning in the spring invigorates the tree. One heading cut results in three to four new stems growing from buds immediately beneath the cut. One cut branch now = 3-4 new branches that need cutting next year. When topping is done the new growth is prolific. This prolific growth shades the interior canopy resulting in death of branches inside where there is too much shade. Thinning cuts. Cuts lower on major limbs on this tree were made with what I call “thinning cuts”. Thinning cuts are made at a juncture of two limbs leaving one limb remaining. This type of cut should be made 95% of the time when we prune. Thinning cuts leave another branch to take the place of the one just removed. This helps decrease the amount of new growth we get from pruning. This type of cut helps retain the natural form of the tree. Determine what you want the tree to do. What do we want from the tree? Is it to give shade? Will people walk under the tree? Does the tree need to be shrunken in size? What we expect from the tree dictates how we will prune the tree. Prune with a purpose in mind. The right approach to pruning a tree like this is to start at the bottom and work up. Make sure the major limbs are necessary. If there are too many, you might consider removing a major limb at the very beginning. This is true particularly if there are just too many larger limbs, if they are crossing, broken or damaged. If the tree needs to be shorter then identify the limbs that need to be lowered and follow them down inside the canopy to a place where you can make a “thinning cut”. Lower the tree’s height be identifying each of these limbs that are too tall and reduce their height with thinning cuts. If the tree is growing toward a building or structure then remove limbs growing in that direction or that will interfere. Make the cuts using what kind of cut? That’s right, a thinning cut, not a heading cut. If we need to allow people or vehicles to pass under the tree identify the offending branch or branches and remove a portion of that limb with what kind of cut? That’s right. A thinning cut. So when do we make a heading cut? Not very often but when we do it is usually for three reasons: increase the density (more new growth; 1 cut=3 to 4 new branches) where the canopy is not dense enough, to add dimensional strength to a limb that is thin and spindly, to increase side branching to increase fruiting or flowering on trees that produce flowers/fruit on spurs. A correctly pruned landscape tree should not appear to be pruned when it is completed and done right.

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Pick Fruit and Check for Circling Roots When Repotting Lemon

Leave a Comment / citrus, container, desert, girdling roots, Las Vegas, Mohave Desert, Mojave Desert, nevada, planting, pot bound, potbound, replanting /

Q. I purchased a lovely Meyer Lemon tree in a one gallon pot in middle of the spring. It already had 6 lemons on it. I have the original fruit, have new fruit growing, and still am getting blossoms. Should I transplant it now into a larger pot or wait until after the fruit ripens and is used? A. Remove any mature lemons from the tree.  Lemons should not remain on the tree longer than about late December and possibly early January at the very latest.  Check for circling roots in the container before planting. This is early enough you might be able to correct it.             Leaving lemons on the tree can disrupt the flowering fruiting cycle for the next season.            If you are planning on putting it in the ground then I would just wait until you have that spot prepared if it is this spring. If you are planting this fall then you might want to repot it into a larger container and wait for fall planting. When circling roots get to be this far along they can no longer be corrected.             If you do repot, check the roots for circling inside the container. This is a common problem in nursery grown trees, called “potbound”, sold in containers. Planting a tree with roots circling in the container and not trying to fix this problem before planting can lead to some serious problems down the road.

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Do Liners at the Bottom of Raised Beds Help or Hinder?

1 Comment / desert, Las Vegas, Mohave Desert, Mojave Desert, nevada, raised beds, vegetable garden /

Q. I’m setting up some raised beds for planting this spring and wondered about water evaporation from the soil. Since water retention in the soils here in Vegas is an issue due to the heat would it make sense to put a liner in the beds to help keep the moisture from draining out so quickly? A. No, I would not do that. Water will drain to the liner and begin to puddle or “perch”. You need continuous movement of water through the soil to prevent your raised bed from staying too wet above the liner. Raised bed under construction with cement side walls against a block wall.             In the Las Vegas Valley, water originating from the Colorado River carries significant amounts of salt. Our soils also contain large amounts of salts. Some are good salts and some are not but regardless we must keep these salts moving through our soils.             The best way to do this is to “overwater” our soils to flush salts through the soil. The overwatering does not have to be much, maybe 15 to 20%. But this 15 to 20% has to go somewhere.             To keep these salts moving or eliminated from our soils we have to make sure water leaves raised beds and goes somewhere. A liner at the bottom of the bed slows down this “flushing” action.             If you are going to put some sort of barrier at the bottom make it porous so water can move through it.

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Remove Suckers Coming From Rootstock on Loquat

Leave a Comment / desert, Las Vegas, loquat sucker, Mohave Desert, Mojave Desert, nevada, pruning /

Not sure if I should remove growth below the graft from a Loquat tree. Q. I have a loquat tree that is a few years old. I let it grow without any pruning so far. I did notice one of the branches growing from beneath what appears to be a graft union. Normally I remove any growth from below the graft as I do on my other fruit trees.  That particular branch has new growth just starting.  I was hoping this branch would give me the balance I needed since it was growing outward where there is an open space. Not sure if I should cut growth below the graft from a Loquat tree. Sucker coming from rootstock on loquat. You can see the bud union above it. A. From the picture you sent to me I can see this sucker is coming from the rootstock. Loquat is normally grafted on to a rootstock that is either not a loquat or the rootstock plant is inferior in fruit quality to the one you purchased. Very healthy young loquat             This sucker must be removed. Even if you could keep it, how it is attached to the trunk is weak and will split from the tree when the limb gets heavier from fruit or size. Fruit of loquat             Loquats do nicely here and have some great fruit. Try to keep it out of late afternoon sun and don’t prune it too much so that the canopy is open. It will sunburn and you will have borers in the tree.

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Repairing Lemon Trees From Winter Cold Damage

Leave a Comment / citrus, cold damage, desert, freeze damage, Las Vegas, Meyer lemon, Mohave Desert, Mojave Desert, nevada /

Q. Our lemon tree shows damage after our recent very cold spell.  Some of the leaves are dry and dropping.  Is there anything we can do to assist the tree? A. The damage can take several different stages. The degree of damage depends on the lowest temperature reached, the amount of time at this temperature and the source and condition of the plant.             The first stage is slightly below its tolerant range and results in leaf damage and other soft tissue death while the stems remain relatively undamaged.             The second stage is at temperatures slightly lower or held for a longer period of time. This results in leaf damage or leaf drop and death of smaller stems.             The third stage is complete death of the limbs and trunk back to the rootstock. The rootstock is normally a very hardy citrus grafted on to the more tender citrus.             In this third stage the more valued lemon portion of the tree completely dies but leaves behind the more cold-tolerant rootstock. When temperatures warm, the rootstock will sucker into a totally new, but different, citrus tree.             You can get some idea now by bending some branches and see if they are supple and bend or if they snap off. But you will not really know the extent of the damage until you see new growth in a month or so.             Once you see where the new growth is coming from you can make a decision to keep the tree or remove it and start all over. If you have suckering from the limbs then you might want to prune it back and let it regrow.             If suckers just come from the roots then it would be wise to remove it.

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Ornamental Pear in Bloom Now… A Nice Tree Where it Has Room to Grow

Leave a Comment / bradford, desert, desert landscaping, Las Vegas, Mohave Desert, Mojave Desert, nevada, pyrus, tree selection /

The good and bad about ornamental pear in the desert. I get questions very, very often about which plants I recommend. I am sorry. But I really hate that question. Half of the answer involves will it grow here and how difficult is it to grow AND the other half is the homeowners personal preference. I have no problem with the first part. It is the second part that is really difficult for me to get a handle on. Because it is a personal question. Ornamental or Callery pear. The Good. Ornamental pear, sometimes called Callery pear, has been around in several different forms for a long, long time. I have been watching them here in Las Vegas for nearly 30 years in different locations and surprising to me they really handle alot of adversity. They can handle rock landscapes, droughty conditions, poor soils, lawns and has few pest problems, unlike in some other places. It is a good choice as a street tree and parks. The Bad. I would not recommend it for home landscapes unless you have a fairly big landscape area and it is probably best if you have a two-story home, not a single-level in terms of size. It can get a bit big if well cared for, 40 feet in our desert. Although I have to admit I have not seen one get that tall here. It is not low in water use. Just like any other fruit tree its water use will be moderately high and increases proportionately as it gets bigger. It will perform better in soils improved with compost and covered in wood mulch rather than rock mulch. It can get a some fireblight (bacterial disease) some seasons if it is raining at the time of bloom (February here). It does produce fruit but it is so small it is mostly inconspicuous but can cause some litter under the tree. Winter form of ornamental pear in rock landsxcape with minimal care. In my opinion it has been limbed up too high. I would have liked to see it with more branches lower on the trunk with at least half of its height in canopy. The Ugly. Like most pears, its growth is somewhat upright and tends to get narrow crotch angles which can be improved with proper pruning and limb spreaders. I don’t care for its winter look all that much. Some will disagree with me but the trunk is not all that pretty and its form is just okay in my opinion. It can get iron chlorosis (yellowing of new growth) in some places but can be corrected using iron chelates containing EDDHA. I would recommend it but don’t put it in a small yard and be aware that this is not a low water use plant.

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Joshua Pups Can Be Transplanted

3 Comments / baby agave, desert, Las Vegas, Mohave Desert, Mojave Desert, moving, nevada, relocating, transplanting agave, when /

Q. I have a Joshua tree that is sending out what I’ve been told are “pups”.  In other words, more trees are coming up around the main tree.  Can I transplant the pups to a new area and how do I do that.  Thanks for your help. A.   Pups are produced normally from underground stems or rhizomes.             Not all Joshuas will produce rhizomes that are usually three to ten feet long. If they are closer than this then they could be seedlings and not on rhizomes.            Native Joshuas growing at higher elevations have a greater chance of producing rhizomes than those at lower elevations. I am not sure if this is due to the type of Joshua or the elevation since the research does not say but kind of suggests they are different types of Joshuas.             As you probably know, a Joshua tree stand can be an interconnected web of plants connected by rhizomes or underground stems. Joshuas can also occur from seed. This is not a Joshua but another agave, Agave americana. You can see its “pup” nestled next to the mother plant.             They are difficult to move. Many people believe they must be oriented the same compass direction as they were in the wild to do well.             I would wait about another month before I moved them in early spring. You could take a shovel between the mother plant and the pup and sever the rhizome now. It should not be very deep. Just slice the soil with the shovel as deep as you can in a swath between the two.             Hand water the pup once only. Move the pup around mid-October by taking as much of the soil with it as you can. It does not have to be around the roots of the pup. You just want some of that soil from around the roots to “inoculate” the hole you are putting it into in case there are some beneficial organisms in it.             Make sure the new spot drains easily of water. Water it thoroughly once after you plant it and don’t water it again until next spring and water it deeply again. Water two or three times a year from that point forward. Collecting any Joshua from the wild is illegal and can result in a very stiff penalty.

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