Red Bird of Paradise Girdling Roots and Borers

Q. I have a Mexican bird of paradise that was planted five years ago that suddenly died. It had flourished until now. I pulled out the plant and sent you some pictures of the dead plant, girdling or circling roots and borers that I found in the center of the stem that probably killed it.

Red Bird of Paradise dead in the middle of summer

A. I read your question and looked at the pictures with quite a bit of interest. This is the first time I have heard of flatheaded borers infesting Mexican bird of paradise. These are the same borers that attack fruit trees and landscape plants.

            Flatheaded borers, when they are young, feed just under the "bark" of the tree in the living vascular tissue. The center of woody plants is not living so they stay feeding where they can find water and nutrients. Essentially, they tunnel just under the bark and parallel with it in a random pattern.

Flatheaded borers pulled out of the stem of Red Bird of Paradise

            It is here that these larvae find the most nourishment for growth. When they get larger and ready to pupate or turn into the winged adult beetle, they burrow towards the center of the plant where there is not much nourishment. But this area does offer them protection.

            Here they begin their metamorphosis until they finally emerge as the adult beetle which flies away, mates and the female lays its eggs on the outer surface of susceptible plants.

            It’s not unusual to see some tunneling toward the woody center of limbs or stems. Or at least inside the wood of some plants.

            Girdling roots, larger roots that grow in circles, occur in plants when they are very young at the nursery. The roots of these plants are crammed into small nursery containers where they start growing in circles. They are then moved to larger containers where they continue to grow in circles.

Girdling roots of Red Bird of Paradise probably started when it was first planted from a seedling.

            They are then planted in the landscape where they continue to grow in circles. Gently remove plants from their containers and check for girdling roots before purchasing them. This is the only way you would know if they are girdling or not.

Planting Ornamental Plum in Mid Summer

Q. Would it be safe to plant a flowering plum tree in September or October or should I wait until spring?

This plum will look fairly good in this climate if the soils are amended at the time of planting and the soil is covered with about 4 - 6 inches of woodchips

A. I would wait until maximum daytime temperatures dropped down to the low 90s or high 80s. In Las Vegas that would probably be late September or early October. I would be comfortable planting trees until about 1 November.

Summer temperatures are just too hot for planting

            There are plants that like to be put in the ground when it’s hot. Palms are an example. They don’t like to be planted when it’s cold. The cut off for planting hybrid Bermudagrass is the end of July. It needs about two months of hot weather to knit into the soil.

            Actually, Fall is an ideal time to plant if you can find the plants you want. Fall planting gives you two times when the weather is nice; fall and the following spring.

            If you find a tree on sale now it will take a lot of diligence to keep it from getting damaged because of the heat. I would put it on the east side of the building and make sure it gets protection from the late afternoon sun. Or put it in filtered light.

            If it’s in a 5 gallon container, I would water it twice each day; once in the morning before it gets hot and the second time in the afternoon. Don’t let direct sunlight directly on the container. The surface temperature will heat up to about 160° F in just a few minutes. It can kill half of the roots inside the container facing the sun.

            Get a second container the same size and put some large rocks in the bottom and put the containerized plant inside of it. It’s called double potting. That will help keep the heat off it.

Pruning for Height Control on Miniature Peach

Q. I have a dwarf peach tree that was about a foot when I planted it last year. It has grown about 6 inches now. When can I prune it so it doesn't grow taller than me?  I am only 4 feet 10 inches and I don't want it to grow tall because I’m going to net it.

Miniature (genetic dwarf) peaches. Actually three of them planted in the same hole but 18 inches apart, one "high head" (grafted tall) and two low head (grafted low)..

A. I want to mention a couple things regarding your question. First, perhaps you mean it is a miniature peach and not a dwarf. Sometimes miniatures are also called genetic dwarf trees. To remove confusion let’s call the genetic dwarf trees “miniatures”.

            Sometimes the nursery trade calls peach trees grafted on certain types of rootstocks as dwarf. It’s true they are a little smaller because of these rootstocks, but not much. The term dwarf is more of a marketing ploy as far as peaches go.

Genetic dwarf or miniature peach.

            Genetic dwarf or miniatures are truly much smaller than the so-called dwarfs. They also grow differently and produce their fruit on branches differently. They are truly dwarf compared to standard -sized peach trees and the other so-called “dwarfs”.

            If you have a genetic dwarf or miniature peach, then it will be pruned much differently from other peaches. You want limbs coming from the trunk as low as possible. Bend these limbs toward the ground, like they have a fruit load on them. See if the fruit might touch the ground.

            If the fruit might touch the ground, consider removing the limb or at least cutting it back. Cutting it back might “thicken” and strengthen the branch and give the fruit more support so they don’t touch the ground.

            At this point in its life you just want it to grow. If it has side branches coming from the trunk at around the height of your knee, then it is doing it all on its own. If it’s a single stick and thick as your little finger, cut it at knee height. This cut will cause this solitary stem to start branching.

Bird damage on peach. If the fruit is firm (not hard) and you see this, pick!

            Secondly, why are you using a net? Birds? Harvest the fruit within one to two weeks of its normal harvest period as soon as bird pecks of the fruit are seen. Let the fruit finish ripening inside the house and off the tree. It is still considered “tree ripened”.

Controlling Nutgrass in Lawns

Q. I have a common lawn with my neighbor and it has an infestation of nutgrass that is now spreading into my lawn. How do I stop it? I've read sugar is a good alternative to herbicides but I would like your help to get this under control.

Nutgrass or nutsedge looks like a grass but it grows faster and it can have darker green leaves if it is purple nutgrass.

A. I have never heard about sugar used to control weeds. That is a new one on me.

            Nutgrass, sometimes called nutsedge, is a tough weed to control. Because it’s a sedge, the leaves look very similar to lawn grasses like fescue. Many people don't know it's in a lawn because it looks similar to the grass. It does grow faster than lawn grass and that can be a giveaway. It's also more upright in its growth so that can also give it away. And, of course, when it sets flowers and seed that can give it away.

If you look closely you can see the nut , the namesake for nutgrass. This is its survival mechanism when things go wrong.

            Nutgrass is called that because of the “nut” or tuber that grows below ground. It’s usually brought into home landscapes as a weed when buying nursery plants. Most people think it’s a grass and pull it but the nut in the soil is left behind. The plant and its soil are planted. From there it spreads.

            When it’s pulled like a weed from the soil, the leaves separate from the underground nut easily. The underground nut regrows new leaves. If the leaves are pulled over and over, as soon as you see them, the nut eventually gives up, exhausted, and dies. That is a common “organic” strategy for controlling nutgrass without chemicals.

Very sturdy nutgrass plant probably because it was growing in a vegetable garden.

            It’s also a common strategy when using chemicals. Weed killers burn the top of the plant down, over and over, until the nut just gives up.

            A weed killer that can be sprayed on the grass and only damages the nutgrass is available. It is called “Sledgehammer”. It’s only available for purchase online. In prior years it was only used by professionals. That formulation was called “Manage”.

            A similar strategy is used when spraying Sledgehammer. But sledgehammer actually kills a fair number of the nuts as well. But not all of them. So, it must be sprayed again when the leaves appear.

Sledgehammer available from Walmart

            When to make the second and third applications is very critical. The spray must be applied when the nut has “invested” its energy into the growth of new leaves. Wait too long and the leaves will rebuild the nut. As soon as they appear, no more than four leaves, Sledgehammer is sprayed again. Eventually, after repeat sprays at the right time, you have won the battle.

Summertime is Borer Damage Time

In the middle of summer this is what catches your eye. Limb dieback. Borers in peach tree.

This is the time of year when borer damage in trees and shrubs is most obvious. Limbs are dying. Their damage can be seen from a distance now but they’ve been working hard feeding on the inside of trees and shrubs for months. The telltale sign of borer damage is a single limb or branch with leaves that turn brown and the branch dies. That’s during dry weather which happens a lot here.

Sometime borers will catch your eye because the bark is peeling off the trunk.  Borers in ash tree.

            Borer damage is often times associated with damage to plants from intense sunlight, sometimes called sunburn or sunscald. Damage is often times seen on the hot exposures of a trunk or the upper sides of limbs. A good strategy is cautiously prune plants that get borers. These include many fruit trees, pyracantha, Arizona cypress, loquat, several types of landscape trees and shrubs.

They either cause or are attracted to plant parts damaged by the sun like the upper surface of branches or the south or west sides of the trunk.

            One borer in a small branch can kill it. But it takes two or three borers feeding in the same area of a limb to cause a larger branch to die the same season it is attacked. It’s probable that borers were present in trees, chewing away on the soft succulent inside just under the bark, for years before obvious summer dieback is seen.

The larva (borer) of the adult beetle can be found feeding on the inside of the tree, just under the bark. Borer in Red Bird of Paradise.

            Resistance to borers depends on the health and age of the tree. Healthy trees withstand several attacks by borers before damage is seen. Smaller sized trees are easily killed while larger ones are more resisitant. Sometimes trees are healthy enough that damage is never seen and they “outgrow it”.

            The best time to inspect a tree for borer activity, even if you don’t suspect anything, is immediately after a rain. The rain “softens” the surface of limbs or the trunk. Tree sap associated with the feeding of borers oozes from the trees, at the damaged area, resembling varnish remover oozing from the trunk or limbs.

Sap, either dried or still gooey, can be a dead giveaway of borer activity in some trees. Some trees are just naturally "gummy" and so you cant tell.

            If there is a lot of “varnish remover” coming from a limb or trunk, then there is heavy damage in those areas. Take a sharp, sanitized knife and remove the bark from the trunk or limb. The borers, or flat headed “worms”, lie just beneath the surface in those damaged areas. Remove them and cleanup the wound and let it heal. If damage is too severe, remove it.

Ash Decline Disease Looks Like Drought

Q. I think I have an ash tree. I've been reading about ash tree decline disease with some apprehension. I noticed my tree has bark with damp spots and it's starting to separate from the trunk. Is this a sign of ash tree decline or something else?

As you can see, ash decline looks exactly like the tree is not getting enough water. This is because the disease plugs up the tubes carrying water from the roots to the tops.

A. Probably not. Ash decline starts as dieback of the limbs from the outside, higher up on the tree. A common problem on many ash trees is sunscald or severe sunburn of the trunk and limbs in full sunlight.

            In our climate, sunlight is very intense and will “sunburn” exposed surfaces of some trees. These exposed surfaces can be the trunk, limbs and even the unprotected fruit of some fruit trees. Most of this sort of damage is seen on the West or South sides of tree trunks or on the upper surfaces of large limbs.

            We see this most often on trees that have thin bark covering the trunk and limbs such as some ash trees, locust and honeylocust, and many fruit trees. We don’t see it as often on trees with thick bark covering the trunk and limbs such as pine trees.

            It can be important to leave small stems growing from the trunk and limbs so they provide shade to help prevent damage from intense sunlight. Remove these small limbs when they get bigger than pencil-sized in diameter.

            Scientists don’t agree if these sunburned areas attract boring insects or not. It’s a “chicken and egg” kind of thing; did sunscald attract the borers or borers contribute to the sunscald? Regardless, oftentimes borers are found damaging the tree near these areas.

            It will not hurt the tree to remove the dead surface of the trunk or limb for a closer inspection. Either pull the loose bark from this area or cut it away with a clean knife. Inspect these areas for borer damage. Removing this dead surface area with a sharp knife helps the trunk or limbs heal more quickly. Make sure the tree is getting enough water at each watering and correct an irrigation problem if one is found.

             If you see some borer activity in fresh wood in the sunburned area, the tree will probably recover unless the damage is severe. Get the tree healthy and let it heal on its own. 

Lemon Tree with "Issues"

Q. I have a lemon tree with some possible “issues”. It has been in the ground 10 years, about 8 feet tall, but recently the leaves are turning yellow to brown and the branches are losing leaves in some spots. There is about 3-4" of rock under tree and thick weedblock under the rock.

In our Mojave Desert soils sometimes using rorck mulch on the soil surface can create problems.

A. If you read my column regularly, you may know what I’m about to say. In our desert soils, placing rock on the soil surface beneath fruit trees is a no-no. You might get away with it in other deserts where there has been some form of agriculture, but not here. Frankly, I’m surprised it has taken 10 years for the leaves to begin yellowing and browning. That may be a new record!

            Soils are made up of two major components; the mineral component which is sand, silt and clay and organic component. Our desert soils are extremely low in the organics; the “good stuff” that make soils come alive. We refer to this component as the organic component or “organics” or “organic matter” of the soil.

            Organics in the soil should rot or break down over a few years and disappear if not replaced regularly; every year in vegetable and herb beds or at least every 2 to 3 years around trees, fruit trees and shrubs. Trees and shrubs that originate in deserts, i.e., desert adapted, can tolerate soils with little organics in them. But that’s not true of plants that don’t come from deserts. This includes citrus.

            Your lemon tree is “behind the curve” regarding organics in the soil. The soil is probably extremely depleted. Adding compost or other sources of organics to the soil surface may not make much difference for a couple of years.

            I would remove the rock, punch holes in the soil, pour compost in these holes so that compost can impact the roots quickly. Or lightly mix compost into the upper surface of the soil. Compost tea may help. Add a cup of compost to a 5-gallon bucket of water, stir it, let it seep for a couple of hours and pour it over the top of the rocks. But ultimately you must get organics into the soil near the tree roots.

            Check the irrigation and make sure the tree is getting enough water. An 8-foot citrus tree should get about 20 – 30 gallons of water each time it’s irrigated. The water should be applied to at least half the area under the tree. Next February, add iron chelate to the soil to correct andy possible leaf yellowing due to iron chlorosis.

Grape Screen Idea Not Bug Free

Q. I want to grow grapes to provide a screen between my neighbor's yard and mine. We have a five-foot block wall between us. I want to grow grape vines to seven feet and two feet away yet parallel to the wall. This wall faces south and receives full sun all day. I want a variety that tolerates the sun and heat in this spot.

If using grapes as part of your landscape be aware that they can be "buggy" due to skeletonizers, leafhoppers, whitefiles and all.

A. Most hot climate grapes handle the heat extremely well. You probably want a table or desert grape. Most of the grapes available in grocery stores can be grown in the hot desert. The most popular table grape is Thompson seedless and handles the heat and southern exposure very well.

            When growing grapes, remember the problems with varmints that many landscape plants don’t have. Insect problems include the skeletonizer, leafhoppers, whiteflies and a few other lesser problem insects.

            Birds are a big problem with grapes as well as ground squirrels if ground squirrels are in the area. As the berries begin to ripen and get sweet, it will be a battle for the fruit between you and them.

            Remember these plants are deciduous so they drop their leaves in the winter. They won’t provide much of a visual barrier during the winter. Prune to keep them productive year after year.

Palo Verde Foaming

Q. I have two Palo Verde trees in front of my house. One seems to be fine while the other has struggled for four years. I am told the tree is healthy but every summer it leaks white, sticky foam from the trunk. This foam attracts bees and beetles. The tree has received professional borer treatments twice a year but it’s still bad.

Foam coming from trees that attract flies and other insects are a good sign of slime flux or wetwood disease.

A. Save your money. This is not an insect problem. It is a disease problem but a disease that will not kill the tree. Let me explain.

            You mentioned bees and beetles are attracted to this foam. I am 99% sure, based on the picture you sent and your description, this is a disease called slime flux, sometimes called bacterial wetwood. It is a nonlethal disease to the tree. It attacks only dead or dying wood inside the core of the tree.

            Nonliving wood inside the tree cannot fight off disease microorganisms because it is dead. The only microorganisms which feed on this wood are "saprophytes". Similar microorganisms feed in compost piles and convert raw waste into compost.

            These microorganisms do not feed on living parts of the tree because living parts of healthy trees can “fight back”. Bacteria involved with slime flux create a foam with a characteristic smell of fermenting yeast or brewing beer. This "yeasty" smell attracts flies, bees and other insects such as beetles because this smell resembles rotting or fermenting fruit.

            Normally, this disease bothers us because of these insects and its general “ugliness”. It does not hurt the tree. It may bother us because the foam dripping down the trunk of the tree causes discoloration of the trunk and unsightliness.

            Probably this infection was transferred to this tree by unsanitary pruning practices. I always emphasize sanitizing and sharpening pruning equipment. When a tree is infected with a disease, it is extremely important to sanitize the pruning equipment before pruning a new tree.            There is no cure for this problem. You and the tree must live with it.

            Some arborists may drill a hole into the tree trunk and insert a metal tube just below the foam and sticks out of the trunk. This foam drains inside the tube and drips to the ground without touching the trunk. Make sure any tools and equipment which touches the inside of the tree has been sanitized thoroughly.

Black Plastic Under Rock Problems

Q. I’ve read somewhere that you should not place black plastic under rock used for desert landscaping. I have it there. We are an older couple and cannot remove it easily. Can we do anything else?

Black plastic under rock mulch tears and deteriorates in a few years. Shouldn't be used under rock.

A. I realize you understand that using black plastic is not a good idea under the rock. Using plastic under rock mulch in desert landscapes prevents air from reaching the roots. Roots need water, but they also need to “breathe”. Black plastic is not permanent while rock is. Sooner or later, this black plastic will begin poking through the rock mulch as it is punctured and disintegrates.

            Consider punching air holes through the plastic at the base of trees and other plants to help air reach the roots. The downside of this recommendation is it may cause the black plastic to rip and disintegrates sooner, peaking its ugly head through the rock.

            Don't think you have to remove all this plastic at once. If you see some sticking up through the rocks, remove it until more appears.

            A more expensive option instead of plastic is called a “weed barrier”. This is spun or woven material that “breathes”, allowing air and water movement. I personally don’t particularly like weed barriers because they do not prevent many of our most troubling weeds like common Bermudagrass and nutgrass. Instead I would recommend spending a little bit more money on rock mulch and applying it thicker, perhaps 3 – 4 inches deep instead of two.

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Citrus Roostock Sucker? Look at the Thorns

Q. I'm not sure if the branch at the bottom of my lemon is a sucker or a real branch.  I know if it comes from below the graft to remove it, but I can’t see where it comes from exactly. The leaves from this growth are huge, too.  It's about 6-8 inches from the soil.

Picture of trifoliate orange thorns

A. Look for long thorns. The rootstock used for citrus in our climate is frequently trifoliate orange, which produces an extremely sour, nonedible citrus fruit. It has huge thorns, up to 2 inches long! If this growth does not have thorns, or it they are small, it is probably lemon. The sucker is right on the edge, but I think it is coming from the scion (lemon).

            If you applied compost to the tree as it is growing, it may make some huge leaves. If you use compost as a fertilizer, apply it each year after you harvest the fruit. Water it in thoroughly.

            If you applied woodchips to the soil beneath the tree, apply it in a larger area under the tree as the tree gets bigger. Apply enough so it is at least four inches deep. Keep woodchips 6 inches from the trunk or it can rot it.

In the West, Use Western Redbud

Q. Last Spring(2017) the leaves looked like they were being eaten.  Upon searching thoroughly, I couldn't see any creatures. Tree seemed to be losing some leaves early...some were speckled as shown in attached picture.  I thought the tree would die..Spring 2018...tree in full bloom (with exception of a few branches)...bees were loving it.  Now, it's back to  chewed leaves.  What can be done to establish a healthy tree again. Today, it was fed and watered with attached...what can be done to bring it back to good health.

Leafcutter bee circles in plant leaves. They are good guys.

This is Eastern Redbud. They cannot handle desert soils very well and certainly not rock mulch. Try to find Western Redbud. But use woodchip mulch and apply compost to the soil . Work it into the soil where the roots are.

Its okay but you need compost, soil amendment added to the soil to make it alive again.

Q. The first picture is leafcutter bee. I advocate to do nothing. They are vegetable pollinators primarily since they come out late.

http://xtremehorticulture.blogspot.com/2014/05/leafcutter-bee-perfect-circles-now-seen.html

http://xtremehorticulture.blogspot.com/2014/09/leaf-cutter-bees-destroying-leaves-on.html

As far as the plant health, this is EASTERN redbud. It doesn’t care for our desert soils much. If you put it in soil covered in surface rock mulch get rid of it and use woodchip mulch. Before you apply it, put about ½ bag of good compost like Viragrow’s Soil Pro and water it in. 

Next time you plant, use half and half soil from the hole and compost and then plant it as you water it in the soil making a slurry. Then cover the rootball area with woodchips and not rock. Eastern plants like Eastern soils. Next time try a Western Redbud. Likes our soils much better.

Check and make sure it is getting enough water each time its watered. Not frequency, how often it is applied, but amount of water.

I Want Larger Tomatoes

Q. I have a tomato garden 4x8x1 foot deep. Ever year I put in 3 new plants of early girl, champion, roma.  I redo soil every year and plants get very big with lots of flowers and tomatoes. My problem is tomatoes only get about 2 inches in diameter what am I doing wrong?

Celebrity and Beefmaster from a reader in the Mojave Desert

A. Remember to rotate your tomato family of plants to new locations each year. Try to replant in the same area every five years if possible. Do it AT LEAST every three years to minimize potential disease problems. To learn more about rotating vegetables in the garden go here.

All three varieties of tomatoes are solid producers for the desert. There are several things you can try to get larger fruit. Varieties of tomatoes will have a maximum fruit size dictated by the variety. Heavy crop loads lead toward smaller fruit.

Soil enrichment

Make sure the soil is amended, biologically active and easy to work before planting. A good quality compost goes a long way to improve the soil in all of these regards. When planting, it should be easy to insert a garden trowel into the soil. No digging with a shovel should be necessary after it has been amended.

Fertilizer applications

Fruit size can be affected by fertilizers. Use a pre-planting phosphorus application to the soil at the time of planting. One pre-plant application of phosphorus each growing season should be plenty. Don't forget potassium. Phosphorus is frequently high-end compost but potassium is oftentimes low. Having a little extra potassium in the soil will not cause problems like high amounts of phosphorus can. 

Use light, monthly applications of nitrogen to the soil as a side dressing to boost performance and keep growth at its peak. I like to tell my students, when the soil is giving to the plants, you must give to the soil. When you take from the plants, give something to the plants. Light, continual applications of fertilizer will maximize production.

Bone meal is high in phosphorus

Water

This is a very important limiting factor in fruit size. Smaller fruit are frequently more intensely flavored than larger fruit coming from the same variety. However, we are conditioned to think that bigger is better. If plants are water stressed when the fruit is gaining size, it will result in smaller fruit. This can be good or bad.

Of course soil moisture monitoring is important but what can even be more important is the use of mulch on the soil surface when air temperatures start reaching about 80° F. I don't like straw much because it's hard to work into the soil at the end of the growing season. A light covering, no more than half inch, is all that you need. 

Pine shavings dissolve into the soil quickly and are not a problem when intensely gardening.

I like things you can apply to the surface that dissolve into the soil easier like shredded newspaper, rice hulls, pine shavings used for animal bedding, etc. yes, they can rob the soil of nitrogen but if you're constantly feeding your vegetables it won't make any difference.

Grapes Produce Shiny, Sticky Leaves When Infested with Mealybugs

Q. I discovered some white things on my grape leaves where it is connected to the branch of the trunk. The plant is only in its second year, bought from a local nursery last year. The leaves are green, but the vine does not grow. Please let me know what I should do.

A. The picture you sent was not clear. But what I could see looked like nothing I had seen here before on grapes. Grapes, both wine and table grapes, are being grown more and more in the Las Vegas Valley. It’s only a matter of time before pest problems in grape growing areas will become our problems as well. Some of these problems can devastate grapes.

            The first thing I noticed on the leaves of your grape plant were “shiny” leaves. The upper surface of the leaves was shiny and sticky to the touch. It was attracting ants and bees. This is from insects that entomologists call “piercing and sucking”. I pushed these leaves aside and found mealy bugs. This was a “new” insect for me on grapes growing in the Las Vegas Valley.

            Piercing and sucking insects (aphids are in this group) damage the plant to get at plant juices that are full of sugar. These insects feed and defecate a concentrated, sugary residue that lands on the leaves. This sugary stuff is what attracts the bees and ants.

            A control strategy, that doesn’t involve spraying chemicals on the plants, is controlling the ants. Ants like piercing and sucking insects because of the sugar. They will move young insects to uninfested locations to increase their supply of sugary “honeydew”. Controlling ants reduces the spread of these insects to new locations.

            Soap and water sprays applied directly to mealy bugs and other piercing sucking insects will kill them. There is no poisonous residue left behind so it should be repeated every three or four days until the problem is under control.

Mesquite Trees are Water Opportunists

Q. Do you have any ideas how to stop the flowers produced by mesquite trees? For the past two years mine seems to have gone crazy producing the little yellow flowers that create a constant scum of yellow on my pool all summer long. This mesquite has 1½ long spines on new growth together with the leaves.

Native mesquite in the Mojave Desert just outside of Las Vegas, Nevada. Restrained growth and flowering because of the 4 inches of rainfall the Mojave Desert gets each year.

A. The tree sounds like a native mesquite, perhaps the Honey Mesquite. This tree is native to our desert Southwest, a North American native plant.

            Production of fruit by olives and pods in mesquite, can be controlled by spraying the tree when flowers are open. The flowers must be present and open for the spray to cause the fruit to abort. So, timing of the spray is critical for success. Chemicals like Florel and Olive Stop are used. But sprays to prevent flowering are more difficult to find and apply.

            Under desert conditions of limited rain, flowers are produced only in the spring when temperatures warm up. If the soil has water in it, there will be lots of flowers. If the soil is dry, flowering is sparse. If this tree is watered freely then it is possible it can produce flowers, in waves, all summer long, with each flush of growth.

Mesquite make a good looking landscape tree if pruned and managed correctly. The density of shade has much to do with how much irrigation water it gets in the desert. Infrequent watering would produce filtered shade. Frequent watering produces dense shade. They would grow too fast if grown in wet climates.

            Desert plants, like this mesquite, are opportunists; they take advantage of water when it is present and restrict growth and flowering when water is not available. In other words, growth of all kinds including flowering is tied directly to irrigation.

Mesquite trees do not belong in lawns and they should not have flowers growing beneath them. They are prefect for desert environments.

            Manage its growth and flowering by managing its supply of water. Water less often but with lots of water when you do water. Give it water in the spring to so it can grow and flower and then restrict water the rest of its growing season.

            This restriction of water will curtail its growth and flowering to once a year. At least then the yellow scum needs to be cleaned out of your pool for only three or four weeks each year. 

Plumcots, Plums and Apricots Good Choices for the Desert

Q. I purchased a plumcot fruit tree years ago for my home in New Jersey. I got great tasting, sweet plumcots in early July every year. I never thought it could grow here. Yesterday, I was reading in the Real Estate Section that a house for sale had a plumcot on its grounds. Will they grow here or is it just that particular location?

A plumcot called 'Plum Parfait' producing fruit in the Eastern Mojave Desert. Below is 'Plum Parfait' tree, about six years old and pruned to 8 feet tall entering into fall color in mid October.

A. The plumcot is a man-made hybrid between a plum and apricot. Other hybrids between these two fruit trees, apriums and pluots, also exist. These types of hybrids don’t occur in nature and are not GMO’s but developed the old-fashioned way through plant breeding.

Floyd Zaiger in a propagation house at Zaiger Genetics, one of the plant breeding companies responsible for hybrids like plumcots, apriums and pluots.

            Our climate is a good climate for growing both plums and apricots as well as hybrids like plumcots. In fact, our desert climate is better for growing these types of fruit than the climate in New Jersey. Our intense sunlight and high temperatures help develop high sugar content and good flavor.

Aprium tart made from interspecific hybrid fruit, the aprium.

            Pick a location in the yard that has plenty of sun but away from walls that produce a lot of radiated heat or reflected light. Dig the planting hole plenty wide and mix a good quality compost with this soil when planting.

            Add water to the hole as you are planting to help settle the soil and stake the tree for the first growing season. Cover the soil with a four-inch layer of wood chips after planting. These “dissolve” into the soil where there is water and continue to improve it in the years to come.

Fig Leaves Showing Possible Disease Symptoms

Q. The leaves on my fig tree appear burned after this rain. I foliar sprayed it with Neem oil and soap and fish protein isolate, These trees were planted last fall and mulched with 1 foot of woodchips and looked amazing until now. They are watered three times each week in the summer.

A. The leaves do look like they are diseased. But I have a saying, “When the top looks bad, look at the ground.” First eliminate the easy problems before jumping to more difficult ones.

            I wonder if that 12 inches of surface mulch is rotting the trunk of the tree. It is easy to kill young trees if they sink, the bottom of the trunks buried in dirt, into the planting hole after planting. Or if woodchip mulch on the soil surface is piled against the trunk and kept wet.

            In both cases wet soil or wet mulch against the trunk can cause a disease called “collar rot”. The disease rots the trunk and “chokes” the top of the tree. When this happens, leaves look diseased or as if the plant isn’t getting enough water. This becomes very apparent during hot weather.

            Start on your knees and pull the mulch away from the trunk. Keep it there permanently, 6 to 12 inches away. Next, carefully remove the soil from around the trunk until you find tree roots coming from the trunk growing horizontally.

            If this small area of the trunk looks water soaked, there might be a problem. I will take a small penknife and cut away a narrow strip of the trunk that was buried in soil and mulch. The wood under the strip should be white or greenish white.

            If there is more than ½ inch of soil covering the trunk, or the trunk was buried in wet mulch, the tree may develop collar rot. All you can do is let the covered part of the trunk air dry and hope for the best.

            I have seen collar rot develop on the lower trunk young figs and pomegranate that are buried. Most figs and pomegranates are grown on their own roots. If the top of the tree dies, wait a couple of months and see if anything suckers from the roots or base of this tree. If it does, don’t replace the tree.

            These basal suckers will grow very rapidly into a new tree because the tree already has established roots. When one of the suckers is 12 inches tall, remove the others for a single trunk tree or select 3 to 5 for a multi-trunk tree.

            It’s possible these leaf problems are related to a leaf disease but I don't recognize it. Sometimes when dead areas develop from disease pathogens, the dead area of the is bordered by yellow. This yellowing is where the plant tissue is still dying. Sometimes this yellowing doesn't exist but only because the disease has stopped spreading.

            The humidity in Las Vegas is unusually high right now because of the so-called “summer monsoon” and rains. I expect diseases to pop up during this kind of weather. Having leaf diseases on fruit trees would not be uncommon during this time of year.

            Instead of spraying, driving using a passive approach towards controlling diseases. Remove extra leaves that might be blocking the movement of air and wind through the canopy. As you see leaf diseases, remove the infected leaves and dispose of them. The plant will grow new leaves in places where there is sunlight. Leaf diseases slow down or stop as the weather changes.