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Saturday, June 6, 2015

Viragrow Delivers! : Blossom End Rot Common on Tomatoes Now

Viragrow Delivers! : Blossom End Rot Common on Tomatoes Now: The blossom end of the tomatoes or pepper fruit, not the stem end, has a black spot on it Blossom end rot of tomato and pepper are commo...

What Is This Tree with Yellow Flowers?

Q. I hope you can tell me what this tree is. It is in my friends yard in the Red Rock area.

A. This tree looks like, to me, like a Golden Rain Tree. We used to see a lot more planted in the Las Vegas area perhaps 20 to 30 years ago. With the explosion of so-called desert landscaping and the use of more trees native to the American deserts, we see fewer of these types of trees planted.

This tree is more common in colder climates, particularly in Colorado and Utah and Northern Nevada. It will do a little bit better if it is not planted in extreme hot locations here such as South or westerly exposures.

Koelreuteria paniculata Is the scientific name or Latin name if you want to Google it

You can get some more information here:


Water use of this tree is not particularly high. I would put it around the same as most of our ash trees of a similar size.

It is a good tree for our climate but it should be placed in the medium water use area of a mini oasis landscape or hydrozone. Because of its size it's a suitable tree for single-story homes. It is deciduous so it is also suitable for summer shade.

No particular landscape problems of any merit. No particular insect or disease problems. A very nice medium-sized tree In the arid and desert Western United States. In the eastern United States where there is more rainfall it is considered to be invasive and people are warned about planting it. This would not be the case in our desert climate unless you are close to open waterways.

Canary Island Palm Fronds Dying

Q. I have a canary Island date palm that actually looks like it’s dying, or at least the fronds are. If you look closely even the fronds towards the center appear to be drying out. Have you ever seen anything like this and can anything be done? 
Canary Island Date Palm with Fronds Turning Brown

A. Usually when you see this kind of thing going on in palms it is most likely water related. Like so many times it's either too much or too little water.
When we’re talking about too much, it's not giving it too much water in a single application, it is giving it water too frequently and the soil does not dry out between irrigations.
These types of palms can use a fair amount of water so if they are in a desert landscaping they really need to get a lot in one application. A lot of water meaning 50 or 60 gallons in one irrigation.
They perform really well in a lawn or surrounded by other high water use plants. These are oasis plants, not true desert plants. But keep in mind, they do not like soils that are held constantly wet.
Possible, but less likely, are disease or insect problems. There is a disease problem that can attack the central bud at the top of the trunk, weakening it and eventually killing the tree. If this is the problem, there is not much you can do but wait it out and hope for recovery.
There is an insect called the giant palm borer that can attack the trunk of the tree, weakening it and eventually killing it. You would see holes in the trunk of the tree about half an inch in diameter. These are the exit holes that the adult beetle has flown from.
I would concentrate on whether the tree is getting not enough water or is being watered too often. If you suspect it might be a lack of water, flood the area under the tree with the hose once a week over the next month to see if you can get it to recover.
If the irrigation system is coming on several times during the week you might consider you are watering it too often, keeping the too soil wet. Give it more water during irrigation but do it less often.

Cotton on New Growth of Pine Normal

picture of  "cotton" on pine submitted
Q. I was hoping you could identify what is happening on our Mondale pines. We live on Mt. Charleston at 5000 feet and after the forest fire and flood we planted 7 Modale pines along our property. They made it through the 1st summer and winter and have grown nicely but in the last month or so have developed a cotton on the tips of the limbs.  We water about 9 gallons per tree about 3 to 4 times a week. They are not dropping any needles but we would rather be proactive than reactive and we do not know if this is normal growth behavior 

A. This cotton on the end of the limbs is the natural color of the buds on the ends of shoots and branches as they expand into new growth.

            The white color or cotton as you call it are the sheaths that enclose the bottom of the new needles as they expand. The buds first expand and grow longer and wider. Depending on the health of the tree, this expansion can be fairly short, an inch to an inch and a half or quite long, perhaps up to 4 inches.

In this stage they are called "candles" because they resemble a small thin candle at the end of the branch. Pines are somewhat unique in that all of the needles of the new growth are contained in this candle.  Pine tree candlesbefore they expand
The amount of new growth and how dense the canopy is can be managed by breaking these candles with your fingers. Do not cut them or you will damage the needles emerging from the candle.
Pine candle before it expands

If you want to keep the tree smaller, you would break about half of the candle off when it emerges. This removes half of the new growth that can develop and causes more side branching to occur, thus making the canopy more  dense

This is a handy management tool if you are using these trees for screening or windbreaks. So what I'm saying is not to be alarmed, this is a normal for this tree.


Tuesday, June 2, 2015

Palo Verde a Good Choice for Desert Landscapes

Ash Dieback or Ash Decline? They Both Kill the Tree.

Q. I have a 23-year-old ash on a drip system with 10, five gallon per hour emitters watered twice per week for 30 minutes. It is located on a southern exposure and planted in a rock mulch.  It has a drip system.  The tree has begun to lose leaves and limbs are dying. Is the tree just old or am I doing something wrong?
Ash tree showing die back. This is not the tree mentioned here.

A. You are watering this tree about 50 gallons a week if all the emitters are working properly. As hot weather is upon us, I don’t believe that this will be enough water to support this tree.

That is probably enough emitters for that tree if they are spaced 2 to 3 feet apart under the canopy of the tree. If the emitters are grouped too closely together much of that water will be wasted. You want to wet about half the area under the canopy of the tree each time you water to a depth of 18 to 24 inches.

Instead of just placing emitters under the canopy of the tree, an alternative method is to place other plants under the canopy that require water as well. I believe there are several advantages to the tree in doing this.
Ash decline
May 1st is usually the critical time when we increase the frequency of applied water from once a week (beginning the first week of February) to twice a week.

Unfortunately a couple of the ash tree varieties have been developing this kind of problem since before I arrived in the Valley in 1984. I remember during the mid-1980s I was called out to look at some very large Modesto ash trees near downtown North Las Vegas. These ash trees were on city property and surrounded by turfgrass or lawns that were in very good condition. The trees had leaves which were curling up and dying as well as branch dieback.
Ash decline will kill the branches of ash trees. If the trees are not pruned and maintained properly these trees will become a safety hazard. This ash tree limb from an ash tree with ash decline broke from the tree and hit this house during a mild wind storm.
The plant pathologist for the state of Nevada and I sent samples to pathology labs looking for some answers. It first came back as a disease called ash yellows but it was later found that this diagnosis was incorrect by the same laboratory. The landscape contractor I was working with, Nanu Tomiyasu, had tried fertilizers, increasing the amount of water to the tree even though it was in a lawn and nothing seemed to help. He was desperate for answers.

Dieback occurring on fantex ash
Fast forward now to 2015. This disease on ash, first found on Modesto ash, has been found on other ash varieties like Arizona ash that have been introduced into the Valley since that time. Plant pathologist from the University of Arizona has acknowledged this disease and written about it http://ag.arizona.edu/pubs/diseases/az1124/ calling it Arizona Ash Decline and the University of California has termed it Ash Dieback.

There are some assumptions about this disease but everyone seems to agree that it is not controllable and eventually the tree will become a hazard and should be removed as the disease progresses and limbs die more and more. Increasing the fertilizer and water the plant receives will not help.

I have no evidence for this but I assume that this disease is transmitted by insects such as the Apache cicada which is common here or whiteflies. Putting ash trees in less stressful environments such as lawns or supplying enough water to the tree roots, seems to help prolong its health. I am telling people that this tree will be short-lived in our environment, 10 to 20 years, until this problem is resolved.

They should not be confused with dieback of limbs when older, established ash trees are no longer in lawns but part of a landscape retrofit to desert landscaping. In my opinion, this will shorten the trees life. Before the tree becomes a hazard, please remove it. If this is ash decline there is nothing you can do to save it.

Removing 20-year-old Trumpet Vine Is Not Easy!

Q. I have 20 year old trumpet vines which I have been trying to remove to establish a new garden. The vines have been dug out as best as possible but as I try to establish a new garden I find shoots coming up from roots so deep I simply cannot remove them. Is there a way to completely eliminate the deepest roots from the trumpet vines without poisoning the ground?
Trumpet vine or trumpet creeper growing in someone's property and draping over the wall

A. Trumpet vine is considered "invasive" in some parts of the country. This is usually in places where there is enough rainfall to support their growth without irrigation.Needs water to survive. It is very unlikely to survive in the hot Mojave Desert without irrigation. However it could become established along Lake Mead, the Colorado River, Virgin River, Warm Springs area and along desert washes.

Look here to check on it's invasiveness

The only "organic" method of killing trumpet vine roots is to totally cut off the top of the plant and force it to "sprout" wherever it has spread underground. As this new growth emerges, you will physically remove it with a shovel or hoe. By doing this repeatedly and as soon as new growth emerges, you will eventually exhaust the root system.

As you have already guessed, this will require a lot of diligence on your part. My experience with plants such as these, exhausting the root system by physically removing new growth can take you two to three years.

Another method is to leave the "mother plant" and dig up suckers as they emerge. This helps direct the growth to the mother plant and suppresses the development of sucker growth in new areas. The plant will slowly “give up” growing into new areas as it ages.

There are chemicals that you can use to help you kill the roots. None of them will contaminate the soil for any length of time. They ARE chemicals so if these chemicals land on the soil surface there will be residue left behind but it would be minimal.

If you are careful in applying these chemicals, none of these need to reach the soil. This method relies on applying or dabbing an herbicide on fresh cuts made to the plant. The plant is cut back and herbicides are applied to these fresh cuts with a paintbrush. This technique relies on herbicides to replace a shovel and a hoe.

Herbicides used for this include “dandelion killers” that contain dicamba or triclopyr. You will have to look at the ingredients on the label and the label should state that they can be used for this purpose. The label may call them "dandelion killer", "brush killer", etc. 
Killer and if you look closely at the ingredients, contains dicamba.
Check the label to make sure it can be legally used for that purpose.
Roundup is also used for this job and applied in the same manner. Follow the same dilution that is recommended on the label as a spray. Repeat applications will be necessary because the plant will respond by sending up new growth in different locations. So be prepared to follow up by cutting back in growth and reapplying the chemicals.

Air Pruning Will Work in the Hot Desert with Some Precautions

Q. I just read about air pruning of roots in potted plants using either fabric pots or drilling holes in pots and lining with landscape fabric.  Supposedly, air pruning keeps the roots in "check" so that they do not outgrow the pot.  The idea sounds logical, but with our extreme heat and hot winds, could this work in Vegas? I know that pots kept in the sun will overheat and kill roots.  If the pot is large enough, would it only kill the outer roots, similar to the action of air pruning?
I have some large pots and as I get older, it is going to be very hard pulling the plant, cutting the roots and re-potting with fresh compost. Any thoughts would be appreciated.

A. Air pruning is a form of root pruning. There is nothing new about root pruning. Root pruning is used in growing bonsai to help keep the plants small and reduce the amount of top growth. Root pruning is used in nursery production to restrict the size of the roots and increase the survival of field grown trees that will be harvested and sold as bare root, containerized or balled and burlaped.
Machines like these are used in commercial nurseries for root pruning young trees before they are harvested as bare root or transferred into containers. Root pruning concentrates the roots close to the plant so they can be transplanted with a higher percentage of success.
You can use air pruning in our hot desert with high light intensities if you regulate the solar radiation heating the soils inside the containers during summer months.

Container plants should be repotted every 2 to 3 years as you know. You might be able to skip the part about cutting off some of the older roots but if you do not replenish about one third of the soil it will eventually be like growing a plant in sand or hydroponics. You might be able to use compost tea as a soil drench for the plant in the container. That, and the addition of a good fertilizer plus micronutrients, might get you by.
Hopefully good management of plant root systems can help prevent girdling or circling roots, a huge problem in the nursery industry and passed on to the homeowner and not discovered for many years later.

Just as you stated, air pruning is allowing tender roots to come in contact with dry air thus killing them. This is usually a greenhouse technique.

In the nursery trade we used to use copper sulfate to control plant roots. When plant roots in they did a space treated with copper sulfate, they died back from copper poisoning. Copper did not travel back inside the plant but stayed localized where it came in contact with roots. This was sometimes used in what is called pot-in=pot culture or “double potting” where a plant is grown in a container and that container put inside of another container that had a shallow layer of gravel at the bottom to prevent the two of them from lodging.
We used pot-in-pot culture when growing ornamental trees for a research project in the 1990s. The container inside of the container that was buried into the ground helped keep the container soil cool. This reduced the risk of high temperatures in the soil surrounding the roots and root damage.
Growing plants in black nursery containers
in the hot Mojave Desert runs the risk of
root damage due to high soil temperatures.
The outside pot was buried in the ground nearly up to its rim. The outer pot acted as a "sleeve" for the inner pot and helped prevent potted plants from blowing over in the wind. This was a big problem in the nursery trade and required many man-hours to "right" the plant after a wind.  If copper sulfate was not used on the gravel between plants or the inner pot was not twisted every couple of weeks during the growing season, the roots from the plant in the inner pot would grow through the gravel and through the second pot into the ground and the plant would be ruined.

Air pruning is similar but without the harsh chemicals. When plants are grown in black nursery containers in full sun, one half to two thirds of the root system of that plant can be killed during summer months due to high soil temperatures. Surface temperatures of black nursery containers can reach 170° F in direct sunlight in just minutes. High temperatures spread through the container soil on the sides facing the sun. Damage is worse if the soils are dry.

What to do?
           Paint nursery containers white. This helps to lower the surface temperature 6 to 10° F.
           Keep nursery containers shaded during summer months by double potting them, placing a son barrier on the outside of the container on the South and West sides
           Grow nursery plants in partial shade; 30 to 40% shade is best.
           Water nursery plants just prior to the heat of the day so that soils are moist. Moist soils do not gain heat as much or as rapidly as drier soils.

Sap from Grapefruit Possibly Gummosis Disease

Q. I am having a problem with my grapefruit tree. The branches have some sap coming from them and the leaves are yellow.
Sap coming from the branches of grapefruit tree could be Rio Grande Gummosis Disease which developed from winter freezing injury.

A. The yellowing of the leaves usually indicates the soil is being kept too wet or a need for a specialty fertilizer such as iron.
This is what the tree looks like with gumming on some branches. Notice that one of the branches has a lot of yellow leaves. Damage to branches can also lead to micronutrient deficiencies.
I saw the sap coming from a stem in the picture you sent. This could be from a disease common to grapefruit that have suffered freeze damage during the winter. It is called Rio Grande Gummosis disease which can occur to grapefruit trees suffering from a past stress. A common stress is winter or freezing damage.

Gum forms on the trunk or branches and causes blisters on the trunk. If you cut into the branch or trunk you can see pockets of gum under the bark. If you make a long cut into the wood through the blistered area and into fresh wood you may see a pinkish discoloration in the fresh wood.
Most likely the tree will continue to decline if this is the case. I would remove the tree and find a warmer spot to grow citrus that does not have much winter wind. Wind makes winter freezing temperatures worse.

I would also make sure the soil drains freely when water is applied and use wood chips as a surface mulch to help keep the soil healthy.

You can read more about this disease on grapefruit here from the University of Arizona and copied below.

Rio Grande Gummosis
This name has been given to a gumming disease of mature citrus, particularly grapefruit, thought to be caused by several fungi, but no particular pathogen has been identified.

Symptoms: Symptoms begin as narrow cracks in the bark of limbs and trunk in which a yellow, water soluble exudate accumulates. Gum formation on the trunk or branches and gum exudation from blisters on the trunk continues and forms gum pockets under the bark. The advancing margin of infection is orange to pink. Once sapwood is exposed, wood decay may begin. In later stages of disease, heart rot may also be prevalent.

Control: Several factors have been identified as contributing to disease including freeze damage, poor drainage, and salt accumulation. Weakened and injured trees seem to be predisposed the disease. There is no control other than cultural practices that keep trees in vigorous condition. Good pruning practices that remove freeze damaged wood and encourage fast healing are the best way to prevent disease.

Viragrow Delivers! : Viragrow June Coupons are Here!

Viragrow Delivers! : Viragrow June Coupons are Here!: It's okay to look at the name of a fertilizer but it is more important to look at the numbers. There are three numbers that appear so...

Viragrow Delivers!