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 1^st 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. 

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.

How to Control Powdery Mildew of Grape

Q. I have white powdery mildew on my green, table grapes.  This has not been a problem in the past.  What now? Is this related to the cool, moist weather?

Grapes should have air movement around them to prevent powdery mildew and bunch rots. In the hot desert we have to be careful about giving them full sun throughout the day because of sunburn to the fruit.

A. Yes, powdery mildew on grape is seldom seen here because of our very dry and hot weather. This very cool spring, higher humidity and recent rains has made powdery mildew, as well as early blight on tomatoes a problem. Powdery mildew will disappear when it gets hot and dry.

Horticultural oils can help reduce powdery mildew problems

One thing that really helps control powdery mildew forming on grape bunches is improved air movement around grape bunches as well as sunlight during the morning hours. Sunlight on grape bunches in the late afternoon can cause sunburn on the berries so be careful about giving the fruit too much sun late in the day.

We can usually prevent powdery mildew by removing the leaves around grape bunches for better air movement and keeping bunches dry. Once powdery mildew has started, you may have to apply a fungicide to keep it at bay or eradicate it.

One of the best organic controls of powdery mildew on grape are the horticultural oils. Horticultural oils are mixed with water and sprayed on grape bunches in the early morning hours. There is a precaution in using oil sprays and not to apply it when temperatures are high. However, I have had no problem applying oils during the cool early morning hours.

Insecticidal soaps labeled for disease control have also given some control as well as dusting dry bunches with sulfur dust.

Why Are My Boxwoods Dying?

Q. Can you tell me why my boxwood shrubs are showing signs of dying?

A. The usual reason for this kind of dieback in our climate is either a watering problem (keeping the soil too wet or not watering frequently enough which is drought) or wet mulch against the trunk of the plant.

Boxwoods dying back because soil is kept too wet, they were planted too deep or wet mulch is in contact with their stems.

Be sure you pull any mulch back away from the stems of the plants. Six or 8 inches is enough just so it does not touch the stem when it is wet.

Wet mulch can contribute to collar rot where the lower stem or trunk rots from too much moisture and the presence of disease organisms. The organisms are always there, they just need the right environment to develop. The right environment are wet conditions against the trunk and plant stress. Sometimes they don’t even need the stress.

Die back can also be because the soil is kept too wet. Roots need to dry out between irrigations. If they don’t, they will die back causing the stems to die back as well.

Keeping the soil too wet or too dry can look identical above ground. This is because root dieback or death is the same thing as drought. The roots die and can’t supply water to the top and the plant stems die back due to drought for different reasons; lack of water or too much in the soil causing roots to die.

Pull the mulch away and let it dry out before it gets too far along. It is most likely not a disease in the tops but in the stems or roots.

Black aphids on Chitalpa

Aphids on red Yucca flowers before they Bloom in February

Q. I live 40 miles east of Kingman, AZ and I'm having a bug problem this spring on our chitalpa and ocotillo. There are tiny black insects on every bloom and bud. I've started noticing them on the red-tipped yucca blooms as well. We've had all of these plants for years and they are well established. We would hate to loose them. Should we be concerned about these bugs? 

A. These are black aphids which are common on Chitalpa, its leaves and flowers as well as other plants. They suck plant juice out of the soft tissue of leaves and flower buds and petals, concentrate the sugars taken from the plant and drop it out of their rear as a high sugar, shiny and sticky concentrate.

Aphids and ants working together

 This sugary concentrate attracts ants and can foster the growth of sooty mold. Sooty mold is not sooty canker, a very bad disease of landscape trees. Sooty mold does not infect the plant but just grows along the surface of leaves and stems and is easy to remove.

 Ants herd and protect these aphids from other insects as well as move them around. Controlling the ants helps to control aphids and sooty mold. These insects will not kill the plants but they will affect your plants floral display. Spray these aphids off of your plants with a strong stream of water and control the ants.

Aphids and ants working together on red Yucca after they flowered

Alternatively, spray the flowers and leaves with insecticidal soap, neem oil, canola oil or horticultural oil. If you are still not satisfied with the results, then you can be more aggressive with a conventional insecticide with aphids and ornamental plants listed on the label.

Remember, conventional insecticides can be much more damaging to beneficial insects and honey bees.

Spray in the very early morning hours or at dusk when honeybees are no longer present. If you look at one of your pictures of the flower buds you will see a ladybird beetle immature (larva) feeding on them. It is grey compared to the black aphids.

They are voracious feeders of aphids but there are just too many for this solo beetle larva to handle. Spray them off with a strong stream of water or use insecticidal soap or horticultural oil to kill them.

Tomato Disease Causing the Leaves Happening Now

Early blight of tomato

There is an issue occurring now in home gardens that may need your attention called early blight of tomato. Early blight of tomato has been seen on the variety called ‘Big Boy’but is probably on others as well.

If left alone this disease will first cause leaf yellowing on older leaves, followed by grey or brown spotting, then dieback of the plant.

Once plant dieback occurs, the fruits are left exposed to intense sunlight where they sunburn.

This disease can be easy to control if you start early. The key to prevention and spread of the disease is sanitation and rotating your vegetables between garden spots.

Remove yellowing foliage at the stem by “snapping” off the leaves or by cutting with a scissors. It is important to remove the infected leaves and stems as early as possible and put them in the trash, not the compost pile.

Prevent the disease from spreading on new foliage by using a fungicide. Any commercial vegetable fungicide will work but those containing in the ingredients chlorothalonil, mancozeb and copper work the best. I talk about it more in depth on my blog.

Fertilize Lawns At Least Three Times Each Year

Q. What time of year should a lawn be fertilized?

A good  fertilizer for established lawns should be
high in nitrogen (first number),
low in phosphorus (the middle number)
and moderate to high in potassium (the third number).

A. For tall fescue lawns, this is 99% of our residential lawns, I recommend at least three times per year if you are using recycling mowers; Labor Day, Memorial Day and Thanksgiving.The Thanksgiving day application may arguably be the most important application of the year in keeping
a winter lawn green.

If you have bermudagrass I recommend Labor Day, Memorial Day and 4th of July. You don’t want to apply anything to Bermudagrass in the fall if you are planning to overseed your lawn to keep it green during the winter.

Most fertilizer bags recommend a rate of 1 pound of nitrogen per 1000 square feet of lawn area. I consider this to be excessive unless this is a very high-end fertilizer containing lots of slow release nitrogen. You can cut that rate in half and get very good results.

It is also very helpful if you can use a mulching mower that chops up the clippings find enough to return to the lawn as a fertilizer.

You can download a copy of my fact sheet on turfgrass maintenance from here

https://www.unce.unr.edu/publications/files/ho/2010/fs1070.pdf

Look for Plants Dying Because of Grubs

This is the time of year when grubs are feeding on the roots of plants. Many of these types of grubs are the same types that feed in compost piles. Some people refer to them as “compost worms”.

Grubs feeding on the roots of Lantana

The adults of these compost worms are frequently large beetles that we see flying in June and July.

Grub Guard is one of the products containing beneficial nematodes

The eggs of these larvae or worms were laid in March. If there are lots of them, their feeding in the months of March, April and May can cause plants like Lantana and agave to decline and even die.

There are organic options. I personally have not used them but I have received good reports on the use of both beneficial nematodes and bacteria specifically designed for grubs.The bacterium is usually referred to as "milky spore".The nematodes are usually referred to as "beneficial nematodes".These do not kill grubs immediately but do have a long-term effect in keeping the populations low over a long period of time. Look for the words Steinernema carpocapsae in the ingredients.

Control of these immature insects is usually accomplished with applications of chemicals as granules or a liquid diluted in water and poured around the roots of the plants. Sprays or dusts applied to the leaves or foliage will not control these types of pests.

This is the insecticide that contains imidacloprid.

One of the most effective chemicals has imidacloprid, as an active ingredient listed in its label and sold by any nursery, garden or box store. But any chemical listed for controlling “grubs” should work and is permitted as long as it includes the plant that your treating on its label.

One word of precautionon the use of imidacloprid; It has been implicated (but not proven) to possibly contribute to some environmental problems including colony collapse disorder of honey bees (CCD).

Research implicating imidacloprid in CCD

If you do use this product, I would not apply it to flowering plants and only apply it as a liquid, soil drench and not as a foliar spray.

If you have any further questions contact me through my email, Extremehort@aol.com, or on my blog Xtremehorticulture of the Desert.

My Zucchini Will Not Produce Any Fruit

Here is a zucchini plant with both male and female flowers. The male flowers are supported by a long thin stalk. The female flowers have a stalk supporting it which is swollen and resembles a small zucchini.

Q. My friends are giving me grief because I can't grow zucchini or other squashes. I get female squash flowers with the squash below the flower. I have male flowers, too. We seem to have insects around enough to pollinate other plants. Fruit withers at about large grape size.  I am thinking that the two flowers aren't opening at the same time for the insects. What can I do to become one of those zucchini and squash growers who have so much they can't even give it all away?

A. The weather right now has been very strange. Give it a chance to warm up a little bit. Summer squash likes warm temperatures.

Zucchini fruit falling off due to high temperatures.

Zucchini usually produce male flowers first followed by female flowers a little bit later. It is possible that they are not open at the same time and having more than one plant should solve that problem.

Bees are needed for pollination. If the plant is very dense, bees may have trouble getting inside the canopy where flowers are located. Try removing some of the leaves in the canopy to make it more open so bees can find the flowers more easily.

Some zucchini have a hard time setting fruit when temperatures are high. You might try hand pollinating. This requires a soft paint brush and transferring the pollen from the male flower to the female flower. This is a pretty good video on hand pollinating zucchini.

Video on hand pollinating zucchini

It is also possible that you have a variety that is just not do well in our climate. I have one right now that I did not select and it is absolutely a lousy producer.

It is not true that you can just pick any old variety and it will do well here because it does well in South Carolina or Ventura, California.

Why Is My Queen Palm Yellow?

This is not the queen palm mentioned in the question.
But this is a very common yellowing that occurs
to queen palm in our desert environment and our desert soils.

Q. I have a queen palm that is recently beginning to yellow. It's done well every year until this Spring. I Miracle-Gro the soil around it every two weeks from spring through Summer. I've given it Palm Food a few times a year. One nursery told me I am watering too much. I severely cut back the bushes on both sides of the tree that were overgrown and covering the base and trunk of the palm for the past couple years. Could that possibly have anything to do with it?

A. First of all, Queen palms are very difficult to grow in this desert climate and in these very difficult soils. They really have trouble because of our hot dry winds and hours alkaline soils that contain no organic material.

Now that we have that out of the way…

Yellowing of palm in our soils is usually related to a lack of iron reaching the foliage. You might try applying some EDDHA iron to the soil. This type of iron works at highly alkaline pH which other irons do not.However it should be applied to the soil in the very early spring before new growth occurs.

Applying iron to the soil this late in the season only corrects foliage produced after you apply it to the soil.  Older foliage, foliage that grew before this soil application, will not green up with a soil application. Yellow foliage must be sprayed with an iron solution to get it to green up. Applications to the foliage have to be done several times to be effective.

This is an example of an iron chelate
used for correcting yellow foliage on plants
with liquid sprays.You must adjust
the pH of the spray or use distilled water
for sprays like this to work.

Here is the proper way to mix and apply iron to the foliage:

1. Mix only enough that you will need for spraying. It will not keep after you mix the dry ingredients with water. You must use it up.
2. Use distilled water if possible. If you use tap water you will have to adjust the pH or alkalinity of the water for an iron application to the foliage to work.If you use tap water, add 1 tablespoon of white vinegar to each gallon of water to lower the pH.If you really want to be sure about the pH, use the pool test kits to get your pH between 6.0 and 7.0.
3. After you have adjusted the pH, add the iron fertilizer to the water. Do not add the fertilizer first and then add the vinegar. If you use distilled water you can skip the vinegar.
4. Add a good wetting agent such as EZ Wet. Why? This is not a gimmick. It is very important when spraying liquids, whether its fertilizer or a fungicide, on the leaves of plants. Follow the label directions but you usually add about 1/2 to 1 tablespoon for each gallon of spray. Add this at the very end and mix it into the spray mixture.
5. Apply this spray when temperatures are cool, such as the early morning or evening. Pump up your sprayer and spray it on the leaves with enough liquid to wet the surface of the leaves or when you see the spray liquid beginning to drip from the foliage. Spraying the foliage for longer than this is wasting your time, spray mixture and money.



This is a good wetting agent for applying liquid sprays.
It is made from an agave extract and cold pressed.

6. Repeat this spray in four or five applications several days apart. The normal way for iron to get inside the plant is from the roots. You are trying to get iron inside the plant in the opposite direction. This is much more difficult. You need multiple applications and a wetting agent such as EZ Wet to get it inside the plant.

I would agree that if you water too often or if you have poor drainage you would see yellowing like this from root damage because the soil is kept to wet. All palms should be watered infrequently but with quite a bit of water when you do apply it.

Other mineral deficiencies that can cause yellowing on palm include manganese, potassium and magnesium. The better palm fertilizers will contain these elements and you will see it in their label. I noticed this is not the case with some palm fertilizers.

I don't see why cutting back shrubs next to the queen palm would have any impact on it.

Queen palms look really pretty in San Diego. They are very questionable growing in the Mojave Desert unless you’ve got the perfect spot for them. Stick to more desert adapted Palms next time and you will have fewer problems.

Controlling Spider Mites in Italian Cypress

Q. I have three Italian Cypress trees that are 20 feet tall.  I have a problem with spider mites and want to know the best way to reduce their populations.  I started spraying them with high pressure water and it got rid of all the webs. Since the trees are so tall I cannot effectively apply a pesticide using my Ortho sprayer and garden hose.

Webbing in Italian Cypress does not always mean spider mites. You need to do the paper test explained below to see if mites are the problem or not.

A. How did you confirm that the problem is spider mites? They are easy to misdiagnose and there are problems that can appear like spider mite problems and they are not.

For instance, not all spider mites create webbing and not all webbing in Italian Cypress means it has spider mites. You can find webbing in Italian Cypress from spiders that are actually good guys and helping you out.

Spider mites normally occur during hot weather. We seldom see them during cooler weather.

An Italian Cypress which has spider mites will have the green needles or foliage beginning to die or turn color, usually grey first. If I look at these needles they will have a dusty appearance if spider mites are present.

Spider mites are extremely small. This one is highly magnified.
They are about the size of the dot at the end of this sentence .

This isn't dust but these are dead spider mites that litter the surface of the foliage. If I see Italian Cypress with dusty needles or foliage I begin to think they might have spider mites. The way I usually determine if spider mites are the problem is to take a white piece of paper and slap the branch of Italian Cypress against the paper pretty hard. This dislodges the spider mites from the foliage and onto the paper.

I then hold the white piece of paper in bright sunlight very still for 15 to 30 seconds. If mites are present, I will see tiny little dots the size of a large period crawling around on the paper. If I brush my fingers lightly across this moving dot on the paper, I will see red smears on the paper.

If the Italian Cypress appears damaged, the foliage or needles appear dusty and I get red smears on the white piece of paper I will conclude the damages from spider mites.

Soap and water sprays are somewhat effective if done on a regular basis (couple of times during hot weather or after a dust storm) as a preventive. Otherwise you would have to apply a miticide effective against spider mites for good control. You would apply two applications about ten days apart to control the hatching of young mites from eggs which are not controlled with the first spray.

Unfortunately this would require that you spray the entire tree if mites are a problem. It is really hard for homeowners to spray much above 10 feet. I do not know of any miticides that you can apply to the soil and get good control.

First, make sure the tree has spider mites and that is the problem. Insecticidal soaps are good first choice but they are not extremely effective in controlling this pest. If you do get it confirmed that it spider mites and they are out-of-control, you will have to spray miticide. Watering Italian Cypress too often causing root disease problems can give them a similar appearance as branches begin to die.

Spraying trees above 10 feet is difficult for homeowners. Pest control operators and arborists have equipment to do this.

We Have Holes in Our Tomatoes!

Q. I have Early Girl green tomatoes with round holes in three of them. Otherwise plant is in great shape. Other fruits on plant OK. .

A. That is feeding damage probably by the tomato fruitworm. Applications of Bt or spinosad should slow them down and are "organic" controls.This is basically the same "worm" that attacks the ears of corn by laying its eggs on the new silk coming from the forming ears.

The tomato fruitworm is probably the most damaging pest to tomato fruits. As the name implies, the damaging part of this insects lifecycle is the "worm" stage or more properly called "larva".

Click here to see the larva or immature form before it becomes a moth

They don't all come in one color so they can range in colors from pale yellow, to red, green or even brown with pale stripes down its length. They are about an inch and a half long when fully grown but they can be smaller than this if they are not yet mature.

Unlike hornworms which are pretty easy to spot during the day or at night  with a black light because they glow green,  fruitworms you wont see until you see damage to the tomato fruit. With your black light you can go scouting for hornworms and scorpions at the same time!

The adult of the fruitworm is a night-flying moths that ranges in color from tan to brown with orange in it. They are about 1 to 1 1/4 inch across their wingspan.

Click here to see the adult moth

Because they fly at night that's when the egg laying occurs.They like to lay their eggs on tomato leaves close to green fruit or they might lay them on the leaves on the outer edge of the plant if the plant is dense. They are flying now and have been flying for quite some time.

Click here to see a close-up of an egg

The eggs that they lay are very difficult to see because they are so small.The eggs are white when first laid and then develop a brown stripe or mark just before they're ready to hatch. First they begin to feed on leaves before they attack the fruit. They prefer to feed on green fruit and the damage that they create by tunneling into the fruit causes the tomatoes to ripen more quickly. The fruit is pretty well demolished once they enter and feed and move on to a new fruit.

Shining a white light or black light against a white sheet at night is an easy way to see if they are flying.  You can try it now and you will probably attract some but the best time is when tomatoes begin to flower so you can time your spraying.

You can also use pheremone traps.

Black light or even light traps serve as a good indicator when these guys are flying and will be a problem in the garden in the future. This is a cool way to look for them and great to show kids and grandkids.

Early Blight Control on Tomato Step-by-Step

How to use a foliar spray of Neem Oil plus EZ Wet surfactant to prevent early blight from spreading in your vegetable garden.

Posted by Viragrow on Wednesday, May 20, 2015

Control Leaf Footed Plant Bug Now

Posted by Xtremehorticulture on Wednesday, May 20, 2015

Why Are My Tomatoes Not Ripening?

            This cool weather has caused some unusual plant problems we normally do not see in the hot desert. One reader contacted me to let me know that his tomatoes were not quite the size of a tennis ball, still green and didn’t seem to be growing anymore.

Tomato growth and fruit ripening slow during cool night temperatures

            Another reader told me his newly planted grapes were not growing. Both readers wanted to know what to do.

            The answer to both is to wait. Both of these plants love warm weather. In fact, grapes love the heat. Our nighttime temperatures have been in the 50s and 60s. Most plant growth occurs at night, not during the day. Tomato gets chilling injury at 45° F.

Be patient. It will get hot. Tomatoes will ripen. Grapes will grow an inch every 1 to 2 days when temperatures are above 100° F. All we need are warm night temperatures.

Shade Reduces the Flowering of Pomegranates

Q. I'm not getting a very big crop of pomegranates this year. They are about 6 years old. We have a large ash tree in the yard which throws some shade but the pomegranates both get morning sun.  I heard they don't require much water so I was worried they were getting too much. Then the Homeowners Association switched from grass to desert landscaping this past year.

Flowering of pomegranates requires the tree to be in full sunlight

A. To produce fruit, pomegranate need at least six hours of sunlight but does best in full sun. As shade increases on pomegranate, the number of flowers and fruits decrease. Switching from lawns to desert landscaping reduces the overall amount of water pomegranates are receiving. This will affect overall growth, flowering and fruit production.

Pomegranates produce flowers on new growth. If you are getting lots of new growth and there is enough sunlight there is no reason you should not be getting lots of flowers at that age. The key will be the number of flowers it's producing. If the tree is not producing flowers of course it can't produce fruit.

To stimulate flower production they need the same amount of water as other fruit trees. This plant is very drought tolerant but it needs water if it is to be productive. The amount of water depends on its size. The frequency of watering is the same regardless of size.

A six-year-old pomegranate should be at least 4 or 5 feet across. Its height depends on how it is pruned. An indicator it is getting plenty of water is the density of the canopy. Your pomegranate tree or bush should be dense enough you would have trouble seeing through it.

If you are not seeing much new growth and the canopy is not dense, this is usually an indication it's not getting enough water. Of course production increases if fertilizers are applied as well.

Surface wood mulches help retain water in the soil and improved growth and production of these plants.

Grapes like the Heat, Grow Slowly during Cold Nights

Q. My newly planted grapes aren't really growing fast and are a bit more yellow than dark green. I am wondering if I need to water more. I am only watering two times a week or water less. Or if I need to add something to the soil? Or do nothing and stop worrying?

A. Grapes love the heat. It is probably just not warm enough. Watering twice a week is right when temperatures are beginning to warm.

Apply about five gallons each time you water newly planted grapes. Put a steel stake next to them or a piece of rebar and tie them tightly to it so they are straight. Use the stretchable green nursery tape. Do not use wires.

If you are planning to trellis these grapes, remove all leaves along the trunk except the new growth at the tip. You do not want side shoots to develop along the trunk unless you are growing it in a tree form.

Grapes grow slowly during cool weather

The leaf yellowing could be caused by cool nighttime temperatures or a lack of nitrogen fertilizer. Apply nitrogen fertilizer once a month to the soil around the trees and water it in. Do not apply closer than about 12 inches to the plant or you could burn them or worse.

I see from the pictures you sent you have a lot of rock mulch surrounding your fruit trees and vegetables. Our soils have horribly low amounts of organic content, some of the lowest on the planet.

Grapes, all fruit trees and vegetables including strawberries do not like rock mulch at all. This will be a problem in the future. They like “organic” soils, not rock or mineral soils. The small amount of wood chips you have spread a few inches around your plants will not help them at all.

Wood surface mulches need to be at least 3-4 inches deep and a distance of at least three feet from their trunks. Keep wood mulches several inches away from the trunks of young trees and vines.

Gopher Control Includes Several Alternatives

Q. I live in Sandy Valley and will be building some raised bed planters in my backyard. I have seen gopher mounds all over the property and wondering what is the best way to get rid of them before I start this project. One neighbor says they are so prevalent on the north end of the valley they ignore them altogether.

Gophers make pretty big holes and you can find fresh soil pushed from the excavation.

A. Gophers are tough to control. The options are to kill them, exclude them from desirable plants or catch and relocate them. When gophers have other food sources in the neighborhood using repellent plants in your garden might work since your neighbor’s plants will then seem more delectable.

            When gophers find a food source, they make more gophers. Your raised beds will encourage them to set up a base camp, living quarters and a dining commons. The bottom line is they are attracted to your water and the soft, juicy succulent plants you are growing.

There are baits and poisons you can use but you’ll have to be very careful not to poison other animals in the process. Your best option is probably to exclude them from your growing area with a wire mesh barrier. You would need to move all your susceptible production into raised beds and place wire mesh at the bottom of the bed before filling it with garden soil.

It is best to read through this for your options. http://cesonoma.ucanr.edu/files/27165.pdf

Jujube Good Choice for Desert Production, Not Hachiya Persimmon

Fruit of one variety of jujube

Q. I just bought a new house with big yard at Summerlin. I am Asian and there are three trees I want to plant most but I don’t have any experience; Jujube, Hachiya persimmon and white saucer peach. I read some of your articles and decide to ask your advice before I take the action.

A. Jujube, or Chinese date, grows extremely well in our climate and you will have a lot of success growing it here.

The biggest problem is its invasiveness. Jujube suckers from its roots in new locations wherever there is water. These can be distances of 5 to 20 feet away from the mother plant. Over time, you could have a forest of jujube from a single plant. Just keep the suckers eliminated when you see them.

Sadly, Hachiya persimmon does not perform as well here as Fuyu and other persimmons. We have trouble getting good fruit retention (fruit staying on the tree) after the fruit has set. Plenty of blossoms but the fruit drops when it gets about ½ inch in diameter and the tree produces only a few fruit. I would suggest trying different varieties of persimmons such as Fuyu, Giant Fuyu, Coffeecake, and others).

The white, flat peaches perform very well here with a very high sugar content and excellent flavor. I would suggest donut peaches such as “Stark Saturn” or “Sweet Bagel” varieties. These peaches may also be called saucer or peento peach.

If you keep your trees healthy by planting with plenty of compost mixed in the soil at planting time and covering the soil surface with wood mulch you will have fewer problems. You can always email me with specific questions.

Salt Damage to Peppers Can Be Managed through Irrigation

Q. We are small farmers owning 2 acres of land in India, We have just seen your opinion on RO water for horticulture crops. We are growing roses and colour capsicum under poly greenhouse cultivation. Our ground water electrical conductivity level (salinity) is too bad that it comes to 1.8. So our plants came to death condition. We heard about reverse osmosis system and fixed it to our farm. By this system leaves shrinkage and nutrient deficiency had risen. So we are pleasing to suggest your idea about it. We are looking for your grateful suggestion.

A. Pepper plants are very tolerant of this level of salinity. It only becomes a problem if we let the soil becomes excessively dry or if the drainage of the soil is very poor and the water drains slowly. Improve the drainage of the soil and irrigate so that the soil never dries to less than 60% of its water content. With a little bit of experience, you can determine this just using your hands and feeling the moisture content by squeezing it and using your fingers.

The kind of salts that you have in the soil will dictate if you were to use soil additives such as gypsum or not to help flush the salts from the soil. Sending a soil sample to a soils laboratory to determine which salts are present would be very helpful.

Generally speaking we start to see yield reduction in pepper at about 1.5 dS/m (mmhos/cm). You are close to that threshold at 1.8. I think you would only need to dilute your irrigation water maybe 20% with RO water to get below this threshold.

New Mexico's advice on salt damage to peppers

Another option is to water with your irrigation water and then flush salts using an irrigation cycle using water with lower salts. Use these in an irrigation cycle of salts/low salts/salts/low salts/etc.

Monitor your drainage water for salt content. Monitoring your drainage water and recording it regularly will help you with managing salts (flushing, etc.)

Two types of salt damage occurs to plants; one is due to total salts (EC) and the other is due to the type of salts (specific ion effect). Particularly damaging are sodium, chloride and boron. If these salts are involved then this might mean a very different problem than just salts in general.

What to do?

• If it is possible, determine which salts are present and not just the level of salinity (1.8). 
• When irrigating never let the soil or substrate dry out too much. 
• With high salts you should be irrigating frequently with a smaller volume of water. This prevents the salts from becoming too concentrated. 
• If you can over irrigate and flush salts from your soils make sure you over irrigate by about 20% to keep salts moving through your soil profile and maintain a steady state of salts and prevent the buildup of salts.

Depending on the type of salts in your irrigation water you will see different nutrient deficiencies.

Note: This question was from farmers in India. Potable water, water in the Las Vegas Valley coming from the tap, is close to this level of salinity or salts. This is because a large percentage of this water comes from the Colorado River unless you are on well water. Salt levels of our native soils here in the Las Vegas Valley are 25 times this level. Water management is very important to control salinity.

Relocating Oleander Requires Drastic Measures.

Q. I dug up some standard sized oleanders from my neighbor’s yard. They were healthy for years and some were 8 to 9 feet tall. I transplanted them about six weeks ago and used transplanting fluid every 6 to 7 days. I also watered them every few days. The leaves are all dry and crinkled so I pull them off. They are dead now and just look like sticks. But I see new growth coming from the base. My husband tells me to pull them out and buy some new ones. Will these make it?

A. When you dig up plants that are this old you can only get about 10% of their root system. With a

Oleander will sucker from the base if it is cut back. When relocating an older Oleander you should cut them back to make up for the lost roots.

very small percentage of the root system they will have considerable die back. If they make it at all, they will do exactly what you've described and that is to regrow from the base.

If you want to keep them, it is best to just cut them off with a few inches above the ground and let them regrow from the base. Just keep the soil around the roots watering about once a week now and twice a week when it gets really hot.

They will survive and I would be surprised if anything grows from the stems that are taller. The transplanting fluid was not necessary. They would've done what they're doing right now with or without it.

In the future when you move plants that have been in the ground for more than two or three years the success rate is pretty low unless you have a history of doing it successfully.