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Monday, August 31, 2015

Converting to Desert Landscapes Can Damage Existing Trees

Q. We removed half of our lawn with a 15 year old Chilean Mesquite in the middle which has done very well up to this point. Besides water from the lawn it had its own water supply located near the trunk. During grass removal, roots were chopped and six small plants with drip emitters in the rock mulch surrounding the tree. Will the tree be okay now that the front half sits in rock with only the plant emitters providing water.

A. The short answer is it will not. You need to supply more water to this tree or it will begin to drop its leaves and the branches will begin to die back.
Mesquite roots growing deep for water.
            Now the long answer. Chilean Mesquite is among a group of plants, called phreatophytes, which have the potential to develop a very deep root system when growing in the wild along arroyos. In the case of mesquite, 200 feet or more. This is if the tree is in the right location together with deep, infrequent rains that help establish roots to that depth. Arroyos, or desert gullies, concentrate rainwater in one location pushing water to great depths with the roots of these plants not far behind.
            Phreatophytes like mesquite when grown with water that is applied frequently grow rapidly, vigorously with a very dense canopy. In many home situations, trees do not develop deep roots because the water supplied to them, such as your lawn, is applied only to the surface few inches.
            During 15 years of growth, the vast majority of roots will grow in a “mesh” 12 to 18 inches just below the lawn. The six irrigated plants planted under the canopy will help somewhat but not enough. Removal of tree roots also reduces generally speaking, most trees can lose as much as 50% of their roots and still recover provided they get adequate amounts of water.
            My hunch is your mesquite will start dropping leaves at the onset of hot weather and you will see limb death in the canopy. The roots will try to reestablish themselves wherever they can find water but the canopy will die back because of root loss and inadequate amounts of water.
Tree dieback after converting from lawn to desert or rock landscape.
            What should you do? During this hot weather you should put a hose out there and irrigate the rock beneath the tree about once a week during hot weather. This is a stopgap measure.
            You might consider installing a “bubbler and basin” around the tree in the future to provide more water. Use an irrigation valve previously for the lawn for the water source to bubblers. An irrigation bubbler is installed 2 feet from the trunk. If this basin is quite large, two bubblers located in this basin might be needed to fill it. Each time you irrigate, fill the basin.
Mesquite blown over because shallow rooted due to lawn and flower bed
            It is important that the basin constructed is level and wide enough to lie on top of about half of the area under the canopy of the tree. A level basin, or berm, is built around the trunk approximately 3 to 4 inches high of the tree with the trunk at its center.
            The bubbler is a type of emitter that pushes out usually 1 to 2 gallons a minute. Drip emitters emit gallons in hours, not minutes, so this is a large amount of water applied in one spot in a very short. Of time. This is why the basin or berm is needed.
            If the tree is on a slope, then install the basin around the trees so that it is level. The water from the bubbler must flood the basin and be contained by the basin for it to work well. This may take 10 to 15 minutes with bubblers and anywhere from 20 to 30 gallons every time the tree is watered.
            In midsummer when it's hot this, watering might be once a week to every 10 days or so for desert trees like mesquite. Adjusting how often you water and how much is applied each time will determine how fast the tree grows and how dense the canopy is.
            If you begin to irrigate less often, but apply more water each time, you will slowly encourage the roots of desert trees like mesquite to grow deeper.

Don't Bet on Good Fruit from Rootstock Suckers

Q. I had an old peach tree of about 30 years die. We cut it down and had it removed. Last year several suckers sprouted from below the ground. They have different leaves so I know it is not peach. What are they? Should I leave them alone and allow them to grow?

A. Having a 30 year old peach tree is quite an accomplishment! They are normally a short-lived tree as far as fruit trees go. Peach is hit very hard by borers and may start to decline around 12 to 15 years of age. A 20 year old tree is really getting up there in age.
Rootstock on apricot
            When you purchase a peach tree from a nursery it is grafted (budded) onto a different tree called the rootstock. Basically, there are two different trees joined together; one is grown for its fruit and the other is grown for its roots.

            Frequently, the tree selected for its roots does not produce particularly good fruit. That is not the reason it was selected. It was selected because its roots had some particular quality that was desirable for the entire tree.
            Remove these suckers from the base of the tree. They will grow but the fruit produced will be low quality compared to the peaches that you enjoyed for so many years.

            

Select the Right Plants to Grow With Palms

Q.  I have had this palm for 10 years. Every time I add additional water with a hose or bucket I lose more fronds. Every year I cut higher on the palm to get rid of dead fronds. I drove a metal stake down 18 inches but did not pick up any visible moisture in 3 different places.  Any ideas on how I can go about this from a more scientific method?
Canary Island date palm with aptenia planted at its base
A. I did not see a whole lot wrong with your palm in the picture you sent to me. It is pretty normal for the fronds to begin to brown out and start to die once they drop below horizontal.
            In our climate it is also pretty common to have some tip burn on the leaves along the fronds, particularly as they get older and drop close or below horizontal.
            I did notice you have Aptenia, hearts and flowers, growing at the base of the palm. This plant is not complementary to a palm that has deeper roots. Aptenia has shallow roots so it is watered frequently with a small amount of water. Palms must be watered more deeply and less often.
            If you are going to plant something at the base of a palm, plant something with deeper roots that has a similar watering requirement. Replant at the base of the palm with something more deep-rooted that can give you some color.

            Select a woody perennial that give you season-long color in that spot or an evergreen with a deep root and a similar requirement for water.

Hibiscus Grows Differently in the Desert

Q. My hibiscus plant, transplanted from a pot to my outdoor flower bed, is blooming like it should. But the leaves are not getting any bigger than 1 - 1½" long and ¾" wide. The new leaves also only get to that size. I water and fertilize if with Miracle Grow regularly, but that does not help. Any suggestions?

A. The appearance of plants will be different when grown in different climate zones. I am now on my farm in the Philippines where we have Roselle hibiscus (commonly called Red Zinger) growing. I checked the size of the leaves in response to your email. I normally don’t pay much attention to leaf size just flower production.
            The leaves of our Roselle vary in size from the narrowest at about 3 to 4 inches in length and about 2 inches wide to the largest being 6 to 8 inches long and 4 to 5 inches wide. The largest leaves are growing in partial shade. The smaller leaves are growing in full sun.
            Appearance can also be impacted by your management practices. Let's cover a few of these.
            Climate and microclimates. Plants grown under high light intensities have a different appearance than plants grown under lower light intensities. The principal differences are in leaf size, color and thickness.
            Leaves growing under higher light intensities, provided they are getting enough water and nutrients, will be dark green, smaller, thicker or tougher and develop a thick waxy coating on the leaf surface.
            The same plant growing under lower light intensities will have larger and thinner leaves with a waxy coating that is not as thick. If light intensities get extremely high then we will see leaf discoloration, yellowing or bronzing, on some plants because the light intensity is actually damaging the leaves.
            If the same plant does not receive enough light then the plant will become “leggy” with large distances between the leaves and thin stems that will not support its own weight. The plant will become "floppy".
            Our job as a manager of this plant is to find a good location in our landscape that provides the right microclimate which provides enough light for flowering and an appearance close to what we expect.
            Because we are in a desert, Hibiscus will not look similar to those grown in semi tropical or tropical climates but we can approach that look if we are careful where we plant it.
            Soil. Organic matter such as compost mixed into the soil at the time of planting and applied annually to the soil surface surrounding the plant will encourage larger and healthier leaves. I have seen this numerous times on a number of plants particularly in parts of the plants that are shaded such as lower leaves.
            Fertilizer. Fertilizer will influence the kind of growth. We know that phosphorus fertilizers are very important for flowering, fruiting, root development and production of oils in plants. If not enough phosphorus is present it will impact these types of growth.
            We do not need to apply phosphorus to a soil very often unless it is extremely sandy or growing in hydroponics.
            Nitrogen is different. Nitrogen is important for developing dark green color in leaves and stems and for "pushing" new growth. It is important in producing good leaf size and in the number of leaves and supporting stems produced.
            Nitrogen in soil available to plants also dissolves easily in water. Nitrogen is easily does not dissolve in water easily and is slowly released to plants.
            In your case you want to make sure that nitrogen is applied regularly through the growing season to maintain dark green color and "push" new growth. Combined with moderate amounts of shade, nitrogen will encourage more leaves and larger leaves.
            What should you do? Understand that if your hibiscus is in a very hot, bright location that this location will limit the plants ability to produce larger leaves. Moderate amounts of shade will encourage larger leaf development, particularly in a microclimate that gets morning sun but afternoon shade.
            Apply a 1 inch layer of compost and scratch it into the soil surrounding the plant as much as you can. When you’re done doing this, apply another 1 inch of compost to the soil surface and thoroughly wet the soil deeply. Apply a 1 inch layer of compost to the soil surface every year.
            Apply high nitrogen fertilizer at the beginning of the growing season. Apply a high phosphorus fertilizer after it is finished blooming. If you apply fertilizers at other times of the year, apply liquid fertilizers to the leaves.

            Do not apply any nitrogen fertilizers to the soil after August 1 if you are concerned about winter freezing damage. 

Texas Rangers Can Be Pruned Shorter

Q. Can I trim large Rangers so they are not so tall?

A. Yes you can and you can do it to this plant any time after the major bloom time or this winter. Texas Ranger can handle two different methods of pruning and one of those types will allow you to adjust the size of the plant more than the other method. Texas Ranger can be pruned into a hedge using a hedge shears or pruned into a single shrub.

Texas Ranger showing branches located at the base where pruning cuts can be made.
When any plant is getting too large the same general method of pruning is used to make it smaller. Some plants can rebound after severe pruning (like oleander) and others should be pruned with a more delicate touch.

To make it smaller.....First, identify one branch in the canopy which is too tall. With your eyes and hands follow this branch downward to a location where it joins another branch which is smaller. This location will be a "crotch" or "Y" where two branches are joined together.Make sure the remaining branch is growing in a favorable direction.

You will remove the taller branch by cutting just above crotch with a pruning shears that has been sharpened and sanitized. Make the cut so that the larger branch is removed and there is no remnant of that branch remaining.. The cut should be smooth with no remnant of a stump remaining. Find other branches that are to long or tall and cut them back using the same method. Vary the height of this cut above ground so that all the cuts are not at the same height.

In some cases, you may have to follow a branch a long distance close to the soil to find a favorable place to make a cut. You can remove branches at any of these locations.


If this is an older, large branch that is removed, it may leave a hole in the canopy. These holes will eventually fill with new growth from branches surrounding the hole. It will take a season for these holes to fill again so cut early enough in the season so the holes fill before winter. 

A much more dramatic but sometimes necessary method of pruning older plants is called renewal pruning. Here the shrub is cut nearly to the ground with new growth that will sucker from the cut stems.

The best time to make these pruning cuts are at the tail end of winter or very early spring before new growth starts.

Starting a Fall Vegetable Garden

Q. Could you help me get a fall garden going? Please send me a list of crops that grow in Las Vegas. I live in the northwest area off of Ann Road and Jones in Las Vegas

A. I posted a calendar for planting in the fall on my blog. Download a copy there but I will give you a rundown of the crops which are normally started this time of year in the eastern Mojave Desert.
            First, some background. There are two planting times each year. Plant cool season vegetables and herbs that withstand frost and cold during the late summer, fall, winter and spring months. Plant the warm season, winter-tender vegetables and herbs when danger of frost has passed and into the mid-summer months. Warm season crops die or perform poorly during cold or freezing weather.
            Even though it’s still hot now, this is the time of year to plant several fall and winter crops. Notice that I said many, not all. Exact planting dates vary with soil and air temperatures, the time plants require before they are ready to harvest as well as the quality of the end product.
            Cool season crops that require 60 or more days before harvesting will be just fine if planted now. It is too early to plant crops like radishes which are ready to harvest in 30 days.            
            Exact planting dates vary with your garden microclimate. Gardens located in warm microclimates have different planting dates from those gardens in cooler microclimates. If you are lucky enough to have a landscape with more than one microclimate, you can stagger your planting dates so that the same crops mature a few days or even a week or two apart.
            Plant gardens that face West or South later in the fall but earlier in the spring. Gardens facing east or north are planted in the reverse order.
            The following vegetables can be planted during September from seed or seed pieces for fall, winter and spring harvest: beets, broccoli, carrots, collards, endive, Irish potatoes, kale, kohlrabi, lettuce, peas, rutabagas, spinach and Swiss chard.
            The following could be planted as small transplants: broccoli, Brussels sprouts, cauliflower, cabbage, celery and Chinese cabbage. If temperatures are unusually hot, delay putting in transplants until weather cools off a bit.

            Mulch the soil to keep the seeds and roots of transplants moist and cool.


Sunday, August 16, 2015

Identifying Their Damage and Controlling Borers

Q. I am having a problem with a bug infesting my trees. I haven't identified the pest but I wanted to first ask how did this infestation happen or if it's common in the Vegas Valley and second how is the cycle of reproduction of this bug?

Flat headed borer taken from tree
A. Thanks for sending the pictures. You have taken the larva or “worms” of a beetle from this tree. These larva or worms are called borers. You can notice the flattened head of this worm so it is commonly called a flat-headed borer.

I think it is either the Flatheaded Apple Tree Borer or Pacific Flat Headed Borer. I have been following this insect and its damage for many years in this valley. The adult of this “worm” is a beetle about ½ inch long.
Borer damage on Apple when first seen

The adult female beetle flies around searching for a mate so that it can lay its eggs. It finds a male by “smelling” the male’s pheromone it releases. Most likely this happens any time from about April through August. Once the female mates and prepares to lay eggs, she searches for suitable woody plants that are injured or unhealthy.

Extensive borer damage to Locust
This insect is part of an “ecological recycling cycle” helping plants that are on the decline continue in a downward spiral toward death. However, I have found this insect in trees that appear to be very healthy as well. The female laden with fertilized eggs searches for suitable plants through her sense of “smell”. One of the “smells” she identifies is damage of plants from sunburn.

Discoloration and canker to scaffold limb because of sunburn
High light intensity of our desert sun shining directly on the bark of trees that are thin and don’t provide much insulation become damaged and frequently die in the damaged area. Death in localized areas of the branches and trunk of woody plants leaves behind a “canker” in the surface.

Sunburn damage to Japanese blueberry
The smells and aromas of damaged plants attract the egg-laying of flat headed borers. She lays her eggs in the general vicinity of the damage but on top of healthy tissue. The very tiny worm or larva “hatches” from this egg and tunnels inside the plant just under the bark.

Borer damage to flowering plum
The wood just under the bark is laden with wet, sugary juices from the plant which the flatheaded borer feeds upon. As this flat headed borer feeds, it inches slowly forward just under the bark making a convoluted tunnel. At the beginning of this tunnel is the flattened head and it leaves a trail of sawdust and feces behind it as it feeds, moves and creates the tunnel. I can sometimes push on the bark covering the surface of these tunnels and feel a difference in the “hardness” of the stem.

Borer feeding under the bark inside peach tree limb
This borer matures (pupates or turn into an adult) inside the tree, exits the tree as a winged adult and searches for a mate to repeat the lifecycle. Sometimes, if it is late in the season, this borer will tunnel into the center of a limb to survive the winter and exit as an adult the following spring.

Borer feeding just under the bark of peach tree limb
Borers attack dozens of different trees and shrubs, many in the Rose family. This includes many of our fruit trees, landscape plants in the Rose family like Pyracantha and flowering plum and numerous others as well.

What to do?

Dig it out. Using a sharp and sanitized knife and laying it almost parallel with the branch, I will cut away the surface of the branch to expose the tunneling. I will remove all of the surface bark where there is damage. I will clean the surface bark all away until I have nothing but fresh wood remaining. In this way, I expose the tunneling and the source of protection for the boring insect. This exposes the hiding place to predators of this soft bodied “worm”.

Borer control using a sharp, sanitized knife
Prune it out. If the damage is more than 50% of the branch, I will remove the branch. If removing the branch seems excessive, I will not remove it and give it a chance to heal.

Using insecticide. In a last ditch effort I will use is a soil applied systemic insecticide. I never use these on fruit bearing trees but on ornamentals only. I will use these on non-flowering ornamentals because it is suspected that this systemic may impact bees visiting the flowers. If the tree produces flowers, I time the application of the insecticide just after the time of flowering.

One of the insecticides containing imidicloprid systemic for borer control
Whitewash to prevent. Whitewashing the upper surfaces of limbs, scaffold limbs and the trunk reduces sunburn which should also reduce problems from borers. I make the whitewash by mixing white latex paint 1:1 with water. You can also buy commercial whitewash. In the old days, it was made from lime.
Whitewashing fruit trees in the winter to help prevent sunburn

Pyracantha Does Not like Rock Mulch

Q. I have a hedge of pyracantha on the northeast corner of my property. It is 16 years old.  It grows underneath three large pine trees.  It does not get much sun. The soil, if you can call it that, is mostly just rocks. The plant is thinning and getting bare in the center. The top is still fairly green. The amount of berries in the winter has been decreasing. I dug around the roots as much as I could and amended the soil with Paydirt. I added about a cup of sulpher and some bone meal to the amended soil. I plan to add fertilizer in a couple of weeks. What more would you suggest?  By the way, there is very little yellow on the leaves.

A. Pyracantha is in the Rose family and so it likes soils that are similar to fruit trees in the Rose family. This includes apples, pears, peaches, apricots and the like. It is also susceptible to some of the same problems as fruit trees in that family. It isn’t terribly fond of desert landscapes and rock mulch.

Dwarf pyracantha in winter hedge sheared
Without seeing it I am guessing it is a combination of light as you mentioned, lack of soil improvement, perhaps irrigation, maybe improper pruning and borer problems. Pyracantha needs a lot of sun but it is thin-barked so it sunburns easily if it’s canopy is open. Sunburn leads to borer problems. It is not a desert plant so it likes improved soils and wood mulches. It would like surface mulches made of wood that can decompose. Rock mulch will mineralize the soil over time and it does not like this.

Pyracantha fruit in winter. Pyracantha or Firethorn is in the Rose family.

Pruning is a little tricky but should result in shading any exposed trunk or major branches. From your description it sounds like it has been a hedge pruned; pruned with a hedge shears not pruners. It hedges nicely but I don't recommend this unless you plant it as a hedge. As far as borers, you would see the trunk or major limbs with bark coming off and some darkened areas because of sunburn. Borers can be active for a couple of years and cause no obvious visual damage. There is an insecticide you can apply to the soil that gives the plant season-long control of borers if it is a problem.

Pyracantha in bloom in the spring
So what to do? Check the irrigation and make sure it's getting enough water or increase the amount it gets. I would not increase how often but the amount it receives each time. Pull rocks away from the plant and put down 3 to 4 inches of compost and wood mulch. When pruning, be very careful you don’t open the canopy up too much which might allow sun burning the trunk and limbs. Fertilize once a year in the spring with a fertilizer formulated for flowering woody plants. You can substitute a rose fertilizer which will work. Apply a soil insecticide as soon as you start to see new growth. I hope this helps.

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Hibiscus Blooming but Leaves Too Small

Q. My hibiscus plant, which I planted from a pot to my outdoor flower bed, is blooming like it should.  The problem is, that the leaves are not getting any bigger than 1 - 1½" long and ¾" wide.  The new leaves also only get to that size.  I water and fertilize if with Miracle Grow regularly, but that does not help.  Any suggestions?

A. The appearance of plants will be different when growing in different climate zones. Appearance can also be impacted by your management practices. Let's cover a few of these.
Red hibiscus that produces Roselle growing on our farm, Moca Family Farm, in the Philippines
Climate and Microclimates. Plants growing under high light intensities will have a different appearance then plants growing under lower light intensities. The principal differences are in leaf size, color and thickness. 

Leaves growing under higher light intensities, provided they are getting enough water and nutrients, will be dark green, they will be smaller, thicker or tougher and develop a thicker waxy coating on the leaf surface. The same plant growing under lower light intensities will have larger and thinner leaves with a waxy coating that is not as thick. 

If light intensities get extremely high then we will see leaf discoloration, yellowing or bronzing, on some plants because the light intensity is actually damaging the leaves. If the same plant does not receive enough light then the plant will become “leggy” with large distances between the leaves and thin stems that will not support its own weight. The plant will become "floppy".

Our job as a manager of this plant is to find the right location in our landscape, the right microclimate, that will give it enough light so that it will flower and have an appearance close to what we expect. Because we are in a desert, Hibiscus might not look exactly the same as it does in semi tropical or tropical climates but we can approach that look if we are careful where we plant it.

Fertilizer. The selection of the right type of fertilizer and amount of fertilizer will, to a large degree, influence the type of growth we get from a plant. We know for instance that phosphorus fertilizers are very important for flowering, fruiting, root development and production of oils in plants. 

If not enough phosphorus is present for the plant to use it will impact this type of growth. If too much is present, it can also impact growth of plants by "messing up" the soil chemistry. If fertilizers are applied to the soil, we generally do not need to apply phosphorus frequently.

Nitrogen is a different animal. Nitrogen is important for developing dark green color in leaves and stems and for "pushing" new growth. It is important in producing good leaf size and in the number of leaves and supporting stems produced. 

The nitrogen in soils available to plants are in "salt" form. Applying too much nitrogen can result in leaf burning or scorching along the edges and even plant dieback or death if excessive amounts are applied. Unlike phosphorus, nitrogen is removed from the soil fairly quickly unless it is in organic form. 

The nitrogen will be depleted in 4 to 6 weeks through plant uptake and removal from the soil by the irrigation water and "evaporating" into the air. Organic nitrogen is removed much more slowly and gives the plants a "steady feeding" of nitrogen over a longer period of time.
            
In your case you want to make sure that nitrogen is applied regularly through the growing season to maintain dark green color and "push" new growth. Combined with moderate amounts of shade, nitrogen will encourage more leaves and larger leaves.

Soil. Organic matter such as compost mixed into the soil at the time of planting and applied at least annually to the surface of the soil surrounding the plant will encourage more leaf production and larger leaves on those plants which have it in their genetics to produce this kind of growth. I have seen this numerous times on a number of plants particularly in parts of the plants that are shaded such as lower leaves.

What do you need to do? Understand that if your hibiscus is in a very hot, bright location that this location will limit the plants ability to produce larger leaves. Moderate amounts of shade will encourage larger leaf development, particularly in a microclimate that gets morning sun but afternoon shade. 

Get some compost and dig it into the soil surrounding the plant as much as you can. Apply about 1 inch of compost to the soil surface after you are finished and thoroughly wet the soil deeply immediately after you apply. At least once a year apply compost to the soil surface surrounding the plant and water it in thoroughly. 

Apply phosphorus either to the soil or to the foliage as a foliar spray at least once a year after it is finished flowering for the season. Apply high nitrogen fertilizers to the soil surrounding the plant in early spring, early summer and late summer. Winter tender plants should not be fertilized with high nitrogen fertilizers after August 1.

The three overall factors that will determine the leaf size: 
  • what it's capable of producing genetically (if you know this plant can produce much larger leaves but it is not doing it), 
  • soil improvement, and 
  • application of nitrogen fertilizers.


Oleander Leaf Scorch Disease a Rarity in Las Vegas

Q. We are thinking of putting in a new oleander bush/tree.  But we are concerned about oleander leaf scorch affecting our new plant in the near future.  We've read where the disease has killed oleander in California and Arizona. Has it been found here in the Las Vegas and/or Nevada as a whole?  If not here now, is it wise to put in a new plant?

Oleander with leaf scorch
A. I rarely see any problems on oleander here. Oleander leaf scorch usually occurs in Southern California and not in southern Nevada. I know our state plant pathologist has been watching for it here and is taken several samples looking for it. 

There has been some debate about whether this disease in oleander can be transferred to grapes and cause a similar disease and appearance called Pierce’s Disease. The researcher is pretty firm that it does not.

For more information on oleander leaf scorch I would refer you to the University of California website. If you are convinced that your oleander may be diseased with leaf scorch, contact the Nevada State Department of Agriculture.

Freeze damage of oleander and recovery in the spring
 Diseases are very rare but do happen occasionally. Nothing to worry about. Keep the plants healthy with plenty of water and mulch the soil with organic mulches when possible. Some oleanders are more tender during winter freezes than others. When oleanders become overgrown and woody, cut them within a couple of inches of the ground in the winter and let them grow back from these stumps.

Salt Cedar Removal from Landscapes Is Difficult

Q. What is the best way to remove Salt Cedar, mature trees and the seedlings that are sprouting all over the yard?  Would appreciate any advice you might be able to offer.

A. You should consider getting rid of it but I will warn you it will be difficult. Salt cedar, or tamarisk, produces hundreds if not thousands of seeds every year. The seeds will germinate easily even floating on water or submerged in flooded soils.
Salt cedar is a problem because it uses so much water and kills other plants growing close to it by pulling salt out of the soil, concentrating it in its needle-like foliage and dropping this salt load on the soil surface.
The salt concentrations are so high, very little will grow in these areas. The other problem is that it suckers easily from its roots so just cutting it down will cause it to sucker in many other places.
The most effective way has been to cut it down as close to the soil as possible and apply weed killers to the fresh surface of the cut. Another method is to drill holes in the trunk close to the soil and inject weed killers into these fresh wounds. The two most effective weed killers have been Roundup (glyphosate) and Garlon (tyriclopyr).
The label will tell you the concentration you should use. The best time for treatment is in the fall months just before plants are preparing for winter, not the spring. In our climate this would be October and perhaps early November.
After the tree has been injected and begins to die, you will probably see suckers growing from the roots in a last ditch effort to stay alive. Cut these suckers close to the ground and daub on the fresh cut ends with the same solution.
Do not make the mistake of thinking that a greater concentration of the chemical will give a better kill. Use the labeled concentrations. These were established by the manufacturer and tested in the field.
Seeds from the mother plant may continue to germinate for a long time after the tree is dead and been removed. When these seedlings emerge from the soil, kill them immediately. They can grow 1 foot or more every month during summer. Their roots grew first before the top so it will be deep. 
All of these years I have been working near and around salt cedar and I have no pictures of it. If any of you have some that are yours, send it to me and I will post it here.

Peach Tree Life Limited by Borers

Q. I have a peach tree that has produced magnificent fruit for over 15 years- for the past two seasons I have seen no production or at best tiny fruit that doesn't mature- I have studied your blog and believe that my tree has peach tree borer damage. I live in southern California- zone 9. Should I try to save the tree or is it a lost cause and if so what applications can I use to restore it? I prefer organic methods.

A. I am more familiar with the problems in the Mojave Desert but I would probably agree with you that it is some type of borer. 
Peach trees can be fairly short-lived in many locale because of borers. This includes other countries I have visited. The borers are different but the result is the same. At our orchard in North Las Vegas peach trees that are 15 years old are getting up there in age and a 20 year old tree is old. 
All that being said you can always find someone who has a peach tree that is 40 years old but it is rare and they were lucky or possibly the variety but trees that old are usually not productive any more. 
I would remove it and replace it with another this fall if you can find a variety you like. If you are in a very temperate part of southern California like the San Diego area or along the coast you could do it any time. In the hot desert area, wait until it cools off.

Thursday, August 13, 2015

Cilantro, Parsley and Basil Are Easy to Grow in the Desert

Q. Please, I would like to know what is the best way to grow Cilantro, Italian parsley and basil in Las Vegas. I have tried several times growing them in pots from small plants or directly transplanting them to the raised bed we have. I am not sure if I water them in excess or not enough but the leave start falling out or dry out.

A. All three of these are pretty easy to grow here if you have prepared your soil adequately and growing them at the right time of year. All three can handle full sun but they should not be put into areas of the landscape that are extraordinarily hot due to reflected heat from walls in the late afternoon.
Basil test plots in North Las Vegas. Here we grew 17 varieties of basil and all of them did well under drip irrigation.
I have grown all three of them frequently and have had no problems with them except some insect management. Basil loves the heat and should not be put in the garden until temperatures start to warm
up, perhaps late March or early April if temperatures are warm. They do not like cool temperatures below 55° F.

Cilantro and Italian parsley also do very well here but prefer cooler temperatures of spring and fall rather than the heat of our summer. A great time to plant cilantro and Italian parsley is in the early fall or late summer when temperatures begin to cool off.

Italian parsley growing in North Las Vegas with drip irrigation
If we have a hard freeze you might lose them during the winter months but if winters are mild and you place them in a warm part of the landscape protected from wind they will probably survive the winter. After it gets established and growing well, basil can handle temperatures all the way down to freezing but nothing below freezing.

Parsley Hamburg growing in North Las Vegas. The only problem I had with it was dodder one year.
When temperatures get cold in the late fall and you fear a freeze, throw a light sheet or even better a crop cover over the top of them just before sundown when soils are still warm. This will protect them 5 to 6° F below their freezing point.

Your basic elements of success in this order will be planting at the right time, soil preparation, watering correctly, protection from bugs and location in the yard for protection from cold and wind.

Leaf cutter be damage to basil
Insect problems, generally speaking, include aphids and “worms” which are larva of moths mostly. I would focus on for organic options; insecticidal soap, oils such as horticultural oil or Neem, Bt or Spinosad and a pyrethrum product for fast knockdown. I would use them in rotation as pests begin to appear in the spring and as needed. Leaf cutter bees can be a problem on basil but I do not recommend any insecticides. It is better to cover basil with insect netting or ignore it.

Tuesday, August 11, 2015

Another African Sumac Dropping Leaves in Summer

Q. I have a concern about our 10 year old African Sumac. Is it normal for it to lose large amounts of leaves in the summer? There is new growth, but it is not full and bushy as others in the neighborhood.

A. No, it is not. But be aware that African sumac is a very messy tree for a variety of reason. I have posted information on this on my blog.
African sumac in bloom in February. Achooooo.....










Rose Primer for the Desert

Hybrid Tea rose  'Las Vegas'
Q. I enjoy your page in the RJ, but I cannot see that you ever write about ROSE BUSHES.  We inherited these 14 year old, (estimate), bushes when we bought this house in 2011.  I ask friends, that have roses, and up until this summer, used Lady Bugs, Rose food, have hosed out salts from the roots, etc.  The bushes take up one side of the front of my walk way, plus in 3 other places, and it is important to me, that they look nice.Thank you for your thoughts on my problem.

A. Thanks for asking that question. I seldom generate my own questions so I rely on the public to send these questions to me. It is my hope that people who read my blog and newspaper article will ask questions that many other people are also asking themselves. I seldom try to "second-guess" what people are thinking. Let's cover some general tips on roses and this would be posted on my blog and an abbreviated form of it in my gardening column.

There are two Rose Societies in the Las Vegas Valley; the long-standing Las Vegas Valley Rose Society and a second one which split from the original as the Las Vegas valley became larger, South Valley Rose Society

Get information about the Las Vegas Rose Society
Go to the South Valley Rose Society website

I consider many of these members to be outstanding Rosarians and I defer to them and their expertise. However, I will give you my version of growing roses here in the eastern Mojave Desert.

Roses do extremely well in our climate. The "winter" for roses is during the heat of the summer; June July and August. Expect that roses will look their worst in these months. The rest of the year
Rosa canina, dog rose, used in Central Asia for its high Vitamin C content
they do beautifully and are very prolific bloomers. If you want your roses to bloom during late December and January, plant them close to a south facing wall that throws radiant heat out during the winter.

Our garden rose takes many different forms from miniatures to climbing roses to the garden rose in its many forms such as the Hybrid Teas, Floribundas, Grandiflora and the so-called shrub roses. Shrub roses is a catchall category for those that don't fit anything else. All of them will grow in our climate but an excellent grower and hybridizer of roses, 


puts together a list of roses that do well in our desert climate and publishes it every year 


If you are planning to grow roses, I would strongly suggest that you pay very close attention to your Rose selection by following lists such as these. These are solid recommendations.
Rose 'Nevada' a semi-doubled shrub rose developed in 1927. 

Blah, Blah, Blah. Most of the roses that are popular among home gardeners are what we call "repeat bloomers". Roses weren't always like this. Roses grew in different places all over the world including the Americas but the ancestors of what we now recognize as a modern garden rose had its origins most likely in western China and Central Asia. These areas of the world are very dry. International traders like Marco Polo, before and after him, moved these roses all over the world including the Middle East, northern Africa Eastern Europe and Western Europe. 

Before and after these roses were moved internationally, horticulturists and gardeners began to breed them for different traits. The two traits that probably dominated most of the breeding early on was flower color and repeat blooming. Once the repeat bloomer discovered in China was identified, there was a scramble by many ancient Rose enthusiasts to "breed" this trait into the garden rose. VoilĂ . All of our popular garden roses now are repeat bloomers. Other traits popular were oil production and floral aroma which is tied very closely to the type of oils produced.

Marco Polo trade routes from China
Moving roses from dry Central Asia and western China to the wetter climates of Europe produced an increased number of disease and insect problems. We can see the reverse of this when we grow roses in desert climates. We see disease and insect problems are normally minimal so the need for spraying roses in our climate because of diseases and insects is small.
Aphids on unopened rose flower buds

Selection of roses for the home garden. Use a list like the one I talked about earlier to pick a variety that does best in our desert climate. Nearly all other varieties will do well but growing those selected for the desert that will tolerate the heat and our soils will do better than others.

Straight phosphorus

Planting roses. If you plant into native desert soil, blend this soil with an equal amount of good quality compost. If you are using a good quality soil mix, plant directly into this mix without amending the soil. Add a starter fertilizer high in phosphorus mixed into the backfill surrounding the roots at the time of planting.

Always plant into a "wet" hole, never plant directly into dry soil or a dry soil mix.

Wood chip mulch, not bark mulch, for soil improvement
Always cover the surface of the soil with 3 to 4 inches of mulch that decomposes adding organic matter to the soil as it does. This type of mulch is a "wood chip mulch", not a bark mulch or a rock mulch. If you must use a bark mulch, then use a wood chip mulch first and cover the surface last with bark mulch.
Fertilizers. When first planting roses use a fertilizer high in phosphorus blended into the backfill at the time of planting. Or just use a straight phosphorus fertilizer instead. Once planted, focus on getting some size on the plant by using fertilizers high in nitrogen.
Good high phosphorus fertilizer for roses

Applying a fertilizer once a year in January is sufficient but if you really want roses that "show off" then fertilize more often with a smaller amount of fertilizer each time. Once the rose has established some size in the second or third year of growth, it is ready to start a regular fertilizer schedule focused on flower production. 

Put your first fertilizer application on the soil in January along with a good iron fertilizer such as iron chelate as EDDHA. If you apply iron to the soil, only one application of iron is needed. Apply a fertilizer the second time in April before it gets hot. Avoid fertilizing roses during the heat of the summer.
As the temperatures begin to cool, in mid-September  to early October, make a third application of fertilizer. Just before cold weather sets in, make your fourth application around Thanksgiving. Once roses are mature enough to begin heavy flower production, focus your fertilizers on moderate levels to low levels of nitrogen (the first number) and moderate to high levels of phosphorus (the second number). Always keep your potassium levels moderate to high (third number).

Foliar fertilizer for flowering
You can always substitute foliar applications of a good fertilizer instead of applying it to the soil but this requires more equipment and effort on your part. Foliar applications to roses can be a problem at times because of damage to the flowers.

Some people like to apply Epsom salts to roses. That is a personal choice and there are claims about the value of Epsom salts to roses by many Rosarians.

Irrigation. Roses do extremely well with drip irrigation and wood chip mulch. Use two emitters per plant, one on either side of the plant about 6 to 12 inches away from its center depending on the size of the rose. Once roses are established, water them 2 to 3 times a week during the heat of the summer provided you have the soil covered with wood chip mulch. They will probably need water more often if you don't. 

As temperatures cool in the spring and fall months, water less often but with the same number of minutes for each irrigation. During the winter you may be applying water only once every seven days to two weeks depending on whether your rose is producing flowers or has gone dormant for the winter.

Drip emitter for precise irrigation
The number of minutes to water depends on the other plants on the same irrigation valve. Note the number of minutes you are currently using and select a drip emitters size that will give you 2 to 3 gallons from each emitter during those minutes.

An example: you are planting roses that will use water from an irrigation line which delivers water for 30 total minutes in that irrigation cycle. Answer: Two, 5 gallon per hour drip emitters will deliver a total of 5 gallons in 30 minutes. You would use two, 5 gallon emitters.

Example 2: you are planting roses that will use water from an irrigation line which delivers water for 20 total minutes in an irrigation cycle. Answer: use three emitters. Three, 4 gallon per hour emitters will deliver 4 gallons in 20 minutes. Use three, 4 gallon per hour emitters.

Powdery mildew of rose
Pruning. Major pruning is done in late December to early January. Light pruning can be done at any time. Light pruning is removal of new growth only, such as suckers and growth which is vertical.

Another form of pruning is deadheading. Deadheading is removing old, spent flowers when they are no longer pretty. This will help to encourage more flowers and improves the look of the plants. Remove these flowers at any time they are finished.

Insects and diseases. As I said earlier, insects and diseases are not very common in our desert climate. However, they do occur. Insects to be on the lookout for include aphids, flower thrips, spider mites, leaf cutter bee and cane borer. Japanese beetle has never been reported in southern Nevada and, to my knowledge, mossy gall wasp has not as well.

Iron chlorosis on apricot but shows green veins and yellow
Diseases from disease organisms are infrequent but occasionally occur when overhead irrigation is used (spraying the foliage with water), roses are planted in areas where there is excessive shade or very poor air movement. 

The most common disease is powdery mildew. This can be controlled by selecting a variety that is less susceptible to powdery mildew (another reason to use the list I mentioned earlier) and the crown gall. Other diseases of roses such as black spot, botrytis, winter cold damage or canker are hardly ever, if ever, a problem. 

Problems not caused by disease organisms include iron chlorosis, wind damage and root rots that cause dieback or death from watering too often or poor soil drainage.

When buying roses, make an investment. By a good quality rose right at the start.


Attention All Grade 3 Students Who Want to Garden!

The Bonnie Plants Third Grade Cabbage Program Registration is open now and it is free! 

Gardening teaches kids where food comes from, healthy eating and heightens their engagement with nature. A great way to get kids started in the garden is the National Bonnie Plants Third Grade Cabbage Program, it’s free to any third grade classroom in the country (48 contiguous states), and kids love it!
The program began in 1995 at Bonnie Plants headquarters in Alabama, by 2002; it grew by leaps and bounds and now includes 48 states! Bonnie Plants initiated the program with a mission to inspire a love of vegetable and herb gardening in young people. Each year, Bonnie trucks more than one million free O.S. Cross cabbage plants to 3rd grade classrooms across the country.

Calling all Third Graders! Have you ever tried growing your own food right in your own backyard? Whether you’ve thought about it or not, you can do it, and the National Bonnie Plants Third Grade Cabbage Program will help you.

Here’s how it works…. Every third grade classroom in the 48 contiguous states is invited to join
this fun, free, colossal cabbage growing contest. Yes, it’s a National contest! Growing a cabbage provides third grade students with a chance to win a $1,000 scholarship from Bonnie Plants, plus statewide recognition. Bonnie Plants awards a scholarship to one winner from each state.

Third Grade Teachers: If your third grade class isn’t already registered for this exciting program, it’s simple to get started. You can easily register your class online at www.bonnieplants.com. Just fill out the registration form and submit. Once registered, Bonnie

Plants will truck, direct to your classroom, enough cabbage plants for each of your third grade students to take home and grow. Delivery date(s) are based on geographic region. The cabbage provided is an O.S. Cross; the “O.S.” stands for “oversized” and this variety can grow to be gigantic! In 8 to 10 weeks after planting, students should have a huge, healthy cabbage ready for harvest and program entry.

To view past winners and learn more about the Bonnie Plants Cabbage Program contest visit www.bonnieplants.com and click on the “Cabbage Program” tab at top of screen.

Green Earth Media Group
Joan Casanova
203 292 8820
203 610 2069 (cell)
joan@greenearthmediagroup.com