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Tuesday, January 27, 2015

Crape Myrtle Requires Additional Care in Desert

Q. I want to plant a crape myrtle tree. Will it survive in the northwest area of the Las Vegas Valley? When is the best time to plant and how should it be done? How do you care for this tree so it still looks good in this climate and soils?

A. Crape myrtle does fine here if the whole is dug wide enough and the soil is amended with a good quality compost at the time of planting. This tree is not a difficult tree to grow here but it’s not the easiest either.

Crape myrtle can handle full sun but it should not be placed in a total desert landscape surrounded by cacti and rock mulch. It will perform best in a wetter part of the landscape, surrounded by other plants and with the soil covered in wood mulch.

The three biggest issues to address are modifying the soil enough at the time of planting, mulching the soil surface with wood mulch and using a fertilizer that prevents the yellowing of the leaves occurs because of iron chlorosis.

I would not trust landscapers to plant this tree properly on their own. This tree will not do well if it’s planted in a cheap hole.

The hole does not have to be dug deep; just deep enough to accommodate the tree. But the hole needs to be dug wide. Make sure the planting hole is dug at least three times the diameter of its container or box.

The soil used for planting around the tree’s roots should have plenty of good compost mixed with it. An equal volume of good compost to native soil would be the right amount.

Fertilize once in the spring, around mid-February, with a fertilizer formulated for flowering woody plants, trees and shrubs. A rose or tomato fertilizer could be used as a substitute.

When you fertilize this tree in February give it 2 to 3 ounces of EDDHA iron chelate as a supplement to the fertilizer. Apply it to the soil and water it in.

If you want to give it a little extra attention and have it look even better than apply a foliar fertilizer a few weeks after the leaves come out. Use a product like a Miracle Gro or Peters that is designed to encourage flowering.

Make sure this tree is watered as frequently as your other woody landscape plants and with the same volume of water as plants of a similar size. They are nearly pest free.

Other questions about crape myrtle on this blog:

http://xtremehorticulture.blogspot.com/2012/05/crape-myrtle-and-mimosa-silk-tree.html

http://xtremehorticulture.blogspot.com/2012/09/fertilizer-formula-for-keeping-crepe.html



Tree Trunk Damage Best Left Alone

Q. I have a beautiful 10 foot tall oak that has provided privacy with it's wonderful light green, very dense foliage. I enclosed a picture of a rapidly expanding bark rot-looking area that seems to be circling the trunk and moving upward at the same time. Can this be stopped, cured, or is it life threatening to the tree?
Damage to trunk of oak from reader

A. From your picture, which I posted on my blog, this damaged area of the trunk near the ground seems to be on the mend. You can see the bark “rolling” in over the wound. Allow for the tree trunk to heal on its own. Pull away any rock or wood mulch touching the trunk and make sure irrigation is not too frequent.
Tree tissue rolling over large wound

From the looks of the damage, this was a “traumatic” event and not a disease. After damage like this the living layer around the damage forms a “compartment” that isolates the damage and heals over and around the wound. This reaction is normal to a healthy plant after an injury that is a one-time event and not getting worse.

At first it looked like collar rot, a disease, that was developing but I don’t think so. Just to be on the safe side, pull any gravel or would surface mulch away from the trunk a distance of 12 inches and keep the trunk as dry as possible.

If there is irrigation water applied close to the trunk, then move the source of the water a distance of 18 to 24 inches away from the trunk. When you are watering, avoid daily or every other day irrigations which might keep the soil wet.

Deliver the water the tree needs for several days all at once, not a little bit every day. Judging from the size of your tree this might be around 20 gallons at a time.

Trees of this size should receive water from drip emitters in at least four different locations under the tree canopy. If you are delivering 20 gallons and you have four emitters then they need to run long enough for each of them to deliver 5 gallons each.

In winter, irrigate about once every 7 to 10 days or possibly longer if you can determine the soil still has moisture. In summer time you might water once or possibly twice a week if you have several inches of mulch laying on the soil surface. 

Diversity of Plants Help in Butterfly Gardens

Q. I've been thinking about growing milkweed plants to help in the Monarch butterfly fight. Any thoughts?

A. I agree with you wholeheartedly on encouraging our local populations of butterflies and moths. They add a lot of beauty and grace to our landscape and provide some pollination and act as a food supply.
Butterflies can be pollinators

To my knowledge the Monarch butterfly does not pass through southern Nevada in its migration. I understand there are two migration routes; one from the Eastern population and the other supports the Western population.

The Eastern population misses us completely in its migration routes to Mexico. The Western population is restricted for the most part by the Sierra Nevada mountains.

Instead of focusing just on milkweeds I think a diversity of plant material for attracting these insects might be important. I have posted some reading material on my blog regarding butterfly gardens.
Reducing or eliminating pesticide use in the butterfly garden area would be wise. There are a number of pesticides that are harmful including two that I recommend frequently to organic gardeners: Bt and Spinosad. When considering pollinators both of these insecticides can be lethal to butterflies.

Always apply pesticides, if they must be applied, at times when these creatures are not active. This means the very early morning hours. Many of our moths fly at night so I would avoid applying pesticides at dusk if a major concern are night flying moths.

I put together some links on general information on Monarch butterflies, moths and butterflies of southern Nevada and how to make a butterfly garden. I wish you much success.

Wikipedia on Monarch butterflies

Threats to Monarch butterflies

Map of Monarch routes

Butterflies of southern Nevada.

How to make a butterfly garden in the southwestern desert of the US

Containers Add Benefits to the Balcony Gardening

Pepper in container
Q. I would like to plant roses or tree roses or possibly a shrub on my balcony in containers. They will be getting morning sun and afternoon shade. When should I plant them? Can the pot rest directly on the plate or should there be a space between the pot and the plate? I want to make sure it drains properly and I don’t want the water staining my white balcony.

A. You have a lot of flexibility in this location because they are in container soil and receive late afternoon shade. The limitations would be the total hours of sunlight the plants receive and winter low temperatures. Flowering or fruiting plants need six hours of very bright sunlight at a minimum to do well.

Best times for planting are in February through April or May. Another great time is in the fall from late September to mid-November. The winter months are okay for winter hardy plants but plants don’t establish quickly when container soils are cold.

Roses and other flowering or fruiting plants will be well as long as they get at least six hours of direct sunlight. Weight is a problem on balconies so use lightweight soil mixes that contain a large percentage of perlite or vermiculite. These types of soils need water frequently.

Mint in container

Because of weight, stay with containers no larger than 15 gallon. The plate under the container that catching the water can be in direct contact with the container with no problems.

If you are using tap water then about about 20% of the water that you apply should drain out the bottom of the container to move salts flushed and not accumulating.

You might also consider vegetables, herbs and smaller citrus such as kumquat or lime. 

Tuesday, January 20, 2015

Second Fruit Tree Workshop Scheduled for Henderson January 27

I will be holding a second fruit tree pruning workshop in the Henderson area, in the Warm Springs and Lake Mead area, on Tuesday, January 27 from 1 to 4 PM in the afternoon. The primary focus of this workshop is on citrus and pomegranates.


Other fruit trees we will discuss include almond and fig. The workshop is free to the public but limited to  25 participants on a first-come, first served basis. Registration is through Eventbrite

Register for the event here

We will also be discussing controlling the leaf footed plant bug and correcting the yellowing of leaves on citrus. I will cover all of the management aspects for these trees here in Las Vegas











Sunday, January 18, 2015

What Caused the Holes in My Tree?

Q. I noticed that woodpeckers attacked our Palo Verde tree. There are probably 60 holes around the truck and main limbs. The sap is running even though the holes are just under the surface, not deep. Any advice how to prevent further damage and do you think this can eventually kill the tree?

A. This is probably one of the sapsuckers. Sapsuckers are type of woodpecker and a couple different types have been documented in southern Nevada. Some sapsuckers migrate through the valley and others maintain a year-round presence.
Sapsucker damage to eucalyptus

They damage a variety of trees including fruit trees and many different types of landscape trees. They frequently come back to the same tree over and over.
 The only thing you can realistically do is exclude them from the tree. This means putting up some wire mesh, burlap or other barrier to keep them from the trunk and larger limbs. They will still get into limbs where it is hard to put a barrier.
I have seen the same fruit trees damaged year after year for the past 20 years and the trees still seem to be still doing well. Damaged trees repair themselves more quickly if they are in good health; watered and fertilized adequately. I know it causes damage but it seems to be not life threatening so I would let it go unless the damage gets extensive.

If this seems to be seasonal, you could try some hot pepper sprays just before they begin damaging plants. Mark the event on your calendar and time your applications accordingly.

Lantana Is Get Leggy If Not Cared for

Q. My friend has a lantana plant and the leaves look good from the top to about the bottom few inches and then they turn yellow. What might be the cause of this condition? My lantanas are getting very thin and "leggy". Do you think I should wait until December to cut them to the ground as some say?

A. These plants originate from wetter climates and richer soils. As these plants get older and woodier at the base, they tend to lose their leaves toward the bottom and keep the leaves on the more succulent stems and new growth.



Different Lantanas for home landscaping in the desert

This is worse if the plant is not in full sun or if it is very dense. Regular applications of fertilizer helps along with correctly pruning the plant. Prune these plants to within an inch or two of the soil surface in February if they are leggy. They also need plenty of water so if water is being restricted they will also look pretty bad.
Pruned Lantana 2 to 3 inches high in February if there is cold damage or it has become leggy

Lantana loves full sun and do very well provided the soil has been enriched and it is receiving fertilizer. If planted in rock mulch the soil will become mineralized or lose its organic matter content over time and the plant then does poorly.
Get lantana on a schedule every couple of months with a decent fertilizer for flowering plants. In the spring apply compost or composted chicken manure or something similar around the plant and water it in thoroughly with a hose. You want to re-build some organic matter back in that soil again.
I had several reports of grubs feeding on the roots of these plants. When this happens, the plant begins to decline. It might not be obvious to you unless you dug the plant up and examined the soil.

If you believe this could be a problem, you would apply a granular insecticide or a liquid drench around the outside perimeter of the plant. Granular organic insecticides containing rosemary and thyme oil work as well as conventional insecticides containing imidicloprid.

Climate and Soil Change the Quality of Fruit

Q. Last week I heard about a variety of apple called the Pink Pearl, not Pink Lady.  Will Pink Pearl apple trees survive the Las Vegas growing season?  Do you know where I can get a sapling?

A. I have heard of Pink Pearl apple but I don't how it will perform here. Nearly any apple tree will grow in our climate but it’s really a question of how good the fruit will be. It originated in Humboldt County, Northern California, and it ripens sometime in late August or September. In Las Vegas it might ripen a couple of weeks earlier than that.
Pink lady Apple fully ripe in mid to late November in Las Vegas

The eating quality of a specific variety of fruit is affected by the climate where it is grown, the soils and how it is managed. Pink Pearl has a good reputation in northern California but its quality is unknown in our hot desert climate. I would hate to see you wait four or five years only to find out the fruit is not good quality.

I am confident it will set fruit for you provided it gets pollinated. In its place, I would advise you to select an apple that ripens very early in the summer or in the fall months and avoid apples that ripen during the hot summer months. My experience with apples that ripen in July through August here has not been promising. 

Avoid Bad Haircut When Pruning Rosemary

Q. I have a rosemary bush in the front yard that's very healthy but has grown quite big in the seven years since it was planted. Is there a technique to trimming? I tried once before and it looked like a really bad haircut.
Rosemary with a bad haircut from overzealous hedge shears
A. Any older, woody plant will have its leafy growth on the perimeter of its canopy. If the plant canopy is dense, which is typical of rosemary, all of the leafy growth will be in a 2 inch layer along the outside of its canopy.
Leafy growth needs sunlight. Shade causes leaf drop and prevents leaves from developing. Dense plant canopies don’t allow sunlight to the interior. This means that the woody growth in the interior will be leafless, bare, naked. If you begin cutting away deeper than 2 inches then you will expose the interior, bare wood. This does look like a bad haircut.
The good thing is that bad haircuts are not permanent. New growth emerges from these bad haircut areas because of sunlight and the stimulation the plant receives when it is pruned.
Rosemary pruned around the tree

Shaping plants should begin when they are young. You cannot wait until they are several years old to begin shaping them unless you are willing for that plant to have a bad haircut for a while.
Pruning rosemary depends whether you want it as an ornamental or you plan to harvest the rosemary for cooking. If you are harvesting rosemary for cooking you want to harvest soft succulent growth.
Alternatively you can harvest the woody growth and strip the leaves off. Commercially pruning is done with a shears because it is faster. Again, if you cut too deeply with a shears it will look like a bad haircut.
After pruning always make sure there is enough warm weather for regrowth to occur. Water and fertilize the plant to stimulate new growth and recover from pruning.
If you want your rosemary to be an ornamental, it can adhere to any shape you want to give it. It can be sheared or it can be pruned with a hand pruners. During this last holiday season we saw upright rosemary pruned into small Christmas trees available at nurseries and garden centers. Just don’t cut the plant too deeply.
Rosemary pruned more formally like bangs in a haircut

I prefer a more normal look. This is done by reaching deep inside the plant and removing older wood with a hand shears. By reaching inside to make cuts they are hidden by the remaining growth. If you prune like this, it will never look like the plant was pruned; just smaller.
Rosemary pruned informally


Look for the longest growth, follow the stem back inside the canopy to a place where it joins another branch. Cut and remove the longer stem and leave the shorter one. This would be done in several places each year to keep it restrained.

Pick the Right Variety of Roses for the Desert

Q. I have some of these roses that are the kind that they said are ground cover type but they did very poorly in the Summer, when it was hot. Now I have planted them in the shade and they leaves are turning white then falling off. Could it be that these expensive roses from the Cal coast will not do well here? My other roses are looking great now and getting higher and higher.  These ground cover roses have never looked or done well.

A. Some of the best roses available to us are from Weeks Roses http://www.weeksroses.com/ out of Ontario, California. 

Actually this is a very good climate for roses. The very worst time of the year for them is Midsummer. When planting roses they need full sun and lots of soil amendment at the time of planting. They benefit from 2 to 3 inches of wood chip mulch on the surface of the soil surrounding the plants. 

They don't have a lot of pest problems like they would in wetter parts of the country but in the shade you might expect powdery mildew. Powdery mildew will cause the upper surface of the leaves to turn white and fall from the plant. Powdery mildew seldom occurs if roses are growing in full sun and if they are irrigated through drip irrigation, not overhead irrigation. Overhead irrigation encourages the development of powdery mildew on rose leaves and flowers.
 
Powdery mildew of roses
When selecting roses stay with recommended varieties for the desert. This list of roses can be found on the weeks roses website at http://www.weeksroses.com/_RoseInfo/climate.html


Saturday, January 17, 2015

Fruit Tree Pruning Workshop Saturday AM January 24

Location: South Jones and Patrick Lane area. Exact location will be sent to participants after they register for this class on Eventbrite. There is no fee for this workshop.

Eventbrite - Fruit Tree Pruning Workshop
Older and fruitful Gravenstein apple
 Limited to 25 people only due to the size of the yard. I will be demonstrating how to prepare your equipment, make correct pruning cuts and how to prune apple (20+ years old and one young one), apricot (5 to 7 yrs old), peach (3 to 5 year old), dwarf peach (container), fig (3 to 5 yr old) and pomegranate.(3 to 5 yr old). Location is a residential property in the Southwest of the Las Vegas Valley near South Jones and Patrick Ln. (north of CC 215, southern part of the loop).
Older and fruitful apricot


Tuesday, January 13, 2015

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Monday, January 12, 2015

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I Am Looking for Fruit Trees to Prune

I want to try something different this year.

In previous years I conducted fruit tree pruning workshops at a university facility. This year I would like to try something different. If there are homeowners who would like to cooperate in a community fruit tree pruning workshop in their home landscape, I would be interested in pursuing it during the month of January. We can talk about large fruit trees but I am not prepared to climb them for demonstration purposes.

Interested parties can contact me at Extremehort@aol.com and we can exchange phone numbers.

Requirements.
  • Fruit trees should be between newly planted up to 5 or maybe even 7 years old.
  • Home landscapes should be open to the invited public.
  • Permission to prune fruit trees and use them for demonstration purposes.

How Do You Sterilize Pruning Equipment?

Q. You often discuss the need to "sterilize" your garden tools to prevent transfer of disease. How do you "sterilize" these items?

A. A. What I mean by “sterilize” is exactly what is meant to a medical doctor and for some of the same reasons. Not sterilizing pruning equipment before its use is a terrible oversight. People overlook cleaning and sanitizing equipment because people don't understand why it is needed.
99% of the time unsterilized equipment is not a problem. It’s that 1% of the time when it becomes a problem. These are the times I receive questions about the dieback in olive, mulberry, silk tree and perhaps even ash trees.

Diseases are transmitted. Several important diseases are transmitted on pruning equipment. These include sooty canker (fungal disease of mostly ornamental plants), fire blight (bacterial disease of
Mimosa or silk tree die back due to Verticillium wilt.
many ornamental plants and fruit trees), crown gall (bacterial disease of many woody plants), slime flux (bacterial disease of many plants), Exocortis (viroid disease of citrus and tomatoes), bacterial spot (Xanthamonas, a bacterial disease), sudden oak death (fungal disease), figure mosaic virus, rose mosaic virus, tobacco mosaic virus, Fusicoccum viticolum on grape (fungal disease), Pierce's disease of grapes (5% transmission rate, bacterial disease) and others. I did not include tropical plant diseases like papaya ring spot virus and banana wilt.

Sooty canker on ash.
Cut flower growers and florists also realize the importance of sanitizing knives and pruners to prevent infections from entering the cut flower and promoting its longevity.

Whenever we enter fresh plant tissue with a pruning shears or saw the equipment needs to be sharpened, cleaned and sanitized. Adjusted and sharpened pruning equipment provides a narrow point of entry which minimizes plant damage around the cut. The concept that gardening tools should be kept clean, adjusted and sharpened is less controversial since this makes sense to people.
Equipment should be adjusted, sharpened and sterilized at the beginning of a pruning day. Equipment used for pruning should be sterilized for the same reasons we sterilize hypodermic needles and scalpels. Several important diseases are transmitted on pruning equipment. You can read more extensively about this topic this week on my blog.
Sanitize and sterilize pruning equipment. Here I am using an alcohol wipe after cleaning, sharpening and adjusting the blades.
Unlike a medical procedure which usually enters the body in one location, pruning involves entering the plant multiple times at different locations. So when pruning we must be concerned about transmitting a disease from plant to plant and the possibility of spreading a disease on the same plant to multiple locations.
If trees are healthy, then there is no reason to sterilize or sanitize pruning equipment between cuts or between trees. If the disease is present or you suspect a disease, sanitize between every cut to prevent the disease from spreading within the tree.

Sterilizing methods have been researched and there is some disagreement about what works best. Sterilizing solutions recommended include household bleach, Pine-Sol, rubbing alcohol, trisodium phosphate (TSP), and household disinfectants. 

Household bleach (ex: Clorox): 25% solution (1 part bleach + 3 parts water)
Pine oil cleaner (ex. Pine-Sol): 25% solution (1 part cleaner + 3 parts water)
Rubbing alcohol (70% isopropyl): 50% solution (1 part alcohol + 1 part water)
Denatured ethanol (95%): 50% solution (1 part alcohol + 1 part water)
Trisodium phosphate (Na3PO4): 10% solution (1 part Na3PO4 + 9 parts water)
Quaternary ammonium salts: use as directed on product label
Household Disinfectants (Lysol, etc): full strength

Personally, I have used alcohol and even a cigarette lighter when nothing else was available.
By the way, bleach can be very corrosive to steel. When using bleach, oil your equipment at the end of the pruning day.

Sterilizing and sanitizing solutions have a life span. Dispose of these solutions at the end of the day and reformulate them again when needed. If there is a lot of pruning and equipment is particularly dirty, then sterilizing solutions will need to be reformulated more frequently. 

One excellent method that reduces disease transmission from a piece of equipment is air drying it.  Unfortunately, when you are pruning the cuts are made fairly rapidly and the blades never really have a chance to dry between cuts which increases disease transmission potential, particularly bacterial, viral and viral-like diseases.

How often should you sterilize equipment? Equipment should be adjusted, sharpened and sterilized at the beginning of a pruning day. If trees are healthy then there is no reason to sterilize her sanitize pruning equipment between cuts or between trees.

When you encounter a tree that is diseased or you are not sure if it does have the disease, I would recommend sanitizing between every cut to reduce the potential from spreading it within the tree.

Workers who are moving between properties must sterilize equipment between properties at a minimum. They should be taught that if a tree or shrub looks unhealthy, they need to sterilize between cuts. This is when a rag for wiping off debris and cigarette lighter that can fit into your pocket becomes handy. Any attempt is better than no attempt.

Root pruning. Sometimes I recommend pruning roots of plants. When cuts are made on roots of plants it is important to keep the pruning cut exposed to the open air for 24 to 48 hours before allowing it to come in contact with the soil again. This helps prevent disease transmission from the soil to the plant of soilborne diseases which are numerous.

Encouraging Monarch Butterfly in the Mojave Desert?

Q. I've been thinking about growing milkweed plants to help in the Monarch fight. Two varieties look worth pursuing Asclepias EROSA and SUBULATA. Any thoughts?

A. I grew up in the Midwest and in the path of Monarch butterflies migration routes to Mexico. In fact, as a boy I volunteered to monitor Monarch butterflies for a research study done in Canada back in the 1960's.

After moving to southern Nevada I have not seen any Monarch butterflies in the 30 years I've been here in the Las Vegas Valley. My understanding is there are two migration routes; one from the eastern population of Monarch butterflies and one from the Western population.

Map of Monarch butterfly routes

The eastern population misses us completely in the Western population is pretty much restricted from us by the Sierra Nevada Mountains.

Encourage and sustain local populations. I agree with you wholeheartedly on encouraging our local populations of butterflies and moths. They had a lot of beauty and grace to our landscape and provide some pollination and a food supply. Instead of focusing just on milkweeds I think a diversity of plant material for attracting these insects might be important.

Be careful of pesticide use. Also, reducing or eliminating pesticide use in the butterfly garden area would be wise. There are a number of pesticides that are harmful including two that I recommend frequently to organic gardeners: Bt and Spinosad. When considering pollinators both of these insecticides can be lethal, in particular Spinosad to bees.

Always apply pesticides, if they must be applied, at times when these creatures are not active. This means the very early morning hours. Many of our moths fly at night so I would avoid applying pesticides at dusk if a major concern are night flying moths.

Further reading. I put together some links on general information on Monarch butterflies, moths and butterflies of southern Nevada and how to make a butterfly garden. I wish you much success.

Wikipedia on Monarch butterflies
Donate to Wikipedia

Threats to Monarch butterflies

Butterflies of southern Nevada.

How to make a butterfly garden in the southwestern desert of the US

Time of the Year for Holes to Appear in Trees

Q. I noticed that the woodpeckers have attacked our Palo verde tree. There are probably 60 holes around the truck and main limbs. The sap is running even though the holes are just under the surface - not deep. Any advice how to prevent further damage and do you think this can eventually kill the tree.

A. The only thing is exclusion and putting up some wire mesh to keep them from the trunk. They will still get into the lower limbs since it is hard to put wire mesh there.

Sapsucker damage to apple (above) and eucalyptus, aka gum (below).
I have seen our fruit trees attacked, the same ones, year after year and the trees still seem to be doing well. I know it causes damage but it seems to be not life threatening so I would let it go.

You could try some hot pepper sprays just before they begin damaging plants. Mark the event on your calendar. They are migratory so putting on some sprays might discourage them and force them on to your neighbor’s trees.

Imidacloprid and Bee Decline Linkage

Q. I don't like what I'm reading about Imidacloprid and wanted to know if there is a better insecticide that won't harms bees.

A. Trade names for this chemical name include Gaucho, Admire, Merit, Advantage, Confidor, Provado and Winner.This particular pesticide has a lot of problems and will probably be eliminated in the not-too-distant future because of these problems. Unfortunately, this pesticide is extremely good at what it does and fills a pest control niche that few other pesticides, if any, currently can fill.

We need other choices. The niche that it fills is a very effective borer killer that is systemic and for the most part gives you season-long control. Some of the same reasons it is so good may make it also dangerous to use. Even though the label allows for its use on fruit trees for example, I discourage people from applying it to those trees because it is systemic. I believe that any systemic insecticide has the potential to enter the food that we eat.

Method of application protects bees. Methods of application have a lot to do with exposure to bees. Those pesticides which are applied as a liquid or as a foliar application to the leaves and stems of plants have a higher probability of coming in contact with bees than the same pesticide applied as a soil drench. Soil drenches are liquids applied to the soil and rarely come in contact with bees.

Common products containing Imidicloprid.
Be careful of plants treated. However, this particular insecticide is systemic and can be transported from the roots of plants to the flowers that bees may visit. So in the case of this particular insecticide applying it as a soil drench may still be a problem for bees that visit flowers of plants that were treated with a soil drench. The larval form of many butterflies and moths rely on the leaves of some plants as a food source. Systemic insecticides applied as a soil drench may also be a problem for these insects.

Best use for this pesticide? If we are to continue to use this insecticide perhaps its best use might be as a soil drench on trees and shrubs that are nonflowering and are not used as a food source by anything that we value.

Alternatives? As for alternatives, I do not know one that is this effective for borer control. If we are talking about borer control then prevention is the key. This means preventing sunburn to these plants and keeping them actively growing and healthy is a partial solution.

As for other insect pests that it controls you have many alternatives. However, these alternatives will probably not be as persistent so you will have to apply them more often.

Whenever your focus is on protecting bees you must consider how toxic the chemical is toward these critters, avoiding applications when plants are in flower, applying foliar pesticides at very early morning hours or at dusk when bees have gone home, using pesticides which have a very short life after they are applied and are not persistent in the environment. And even more importantly we must begin to think about the use of pesticides as a last resort, not a first choice when there is a problem.

Pruning Japanese Blueberry to Encourage Growth

Q. I have 13 Japanese blueberry's they have been planted for quite a few years. They have grown tall but only one filled out from the bottom to top because of some shading. This shading is now gone. What can I do and when to stimulate the growth and hopefully have them fill out all over. 

Japanese blueberry picture from another reader.
 A. Severe shading can cause branch or limb dieback. Reduced light to branches can also cause leaf drop and poor growth on living wood.


What to do? Determine if these branches are alive or dead. If they are dead then all you can do is remove them back to the trunk or back far enough to healthy wood. Grasp these branches and bend them. Dead branches will snap like a dry or dead twig. Living branches will bend and not break as easily. If you bend a living branch back far enough of course it too will break so you have to be careful when bending them.

Wait and hope.If they are dead and you have pruned them back, all you can do is wait and hope that light reaching inside the plants will “sprout” new growth and fill in over time. If they are alive then do not prune them all the way back but cut off just a few inches of the ends just far enough to cut into living wood.

Dead branch of Japanese blueberry from another reader.
This might be one or two inches or six or more inches depending on where living wood is located. These types of cuts are called “heading cuts” and remove the terminal buds and will stimulate the plant to fill in bare areas.

When to do this? Do this in about early to mid-February next spring. Fertilize the plants at that time with a tree and shrub fertilizer or even a lawn fertilizer and give the plants a two or three deep waterings with a hose a few days apart. The water from the irrigation system will move the fertilizer into the root area. The fertilizer should be a high nitrogen fertilizer. It would be helpful to give them some iron applied to the soil as well at the same time.

Again More Rabbit Damage!

Rabbit damage to chard. Picture courtesy of another reader.
Q. We live in Sun city Summerlin the rabbits are eating our plants Star jasmine, silver spoon yuccas, and even canary island date palms lower leaves. We have tried Shake-Away Fox and Coyote Urine Granules and scaring them but nothing has worked. Any suggestions or tips would be helpful.

A. These kinds of products are deterrents. Once they are hungry those will not stop them and they will eat even less desirable plants. The only real way to get a handle on them is exclusion (fencing)
which can look horrible. Planting less desirable plants (Arizona fact sheet found on the link below) will help push them to more desirable plants they can find in the neighbors yards.

Rabbit resistant plants Arizona


Fire Barrel Cactus Adds Interest to Desert Landscapes




Care and Pruning of Pyracantha and Honeysuckle

Q. I am writing and enclosing photos of my pyracantha and honeysuckle. I cannot find info on the issue/treatment. A friend suggested I email you after reading the LVRJ column.

A. Thanks for the pictures but they were not very helpful without more information. Let me tell you what I know about these plants and maybe that can help.

Both of these plants grow well in our climate in a mixed, non-desert landscape. They are not desert adapted or desert plants so they will not perform well with rock mulch.

Over time, they will perform better using wood mulch on the surface of the soil.

They should be irrigated at the same time as other non-desert plants. They should be on an irrigation valve that provides water as frequently as other nondesert trees and shrubs.

Most landscape plants require at least one fertilizer application each year in the spring or late winter. You can apply these spring fertilizers into March. Any general landscape, tree and shrub fertilizer will be good.

Pyracantha occasionally develops yellowing due to iron chlorosis so an application of EDDHA iron chelate to the soil at the same time as the fertilizer would be advised. Apply both within a
foot of drip emitters on top of the soil. The iron chelate needs to be covered with mulch.

Pyracantha has a history of borer problems, particularly if it is planted in a southern or westerly exposure in rock mulch with lots of heat and intense sunlight. Borers can be active in the plants and the plant can still appear healthy for one or two seasons.

After a season or two of borer attacks branches turn brown and begin to die back. They normally die back to where the borer damage while the rest of the undamaged plant below this remains green. Prune these dead branches out and let the plant regrow from these areas.

Pictures from reader
Because of the dead branches, the interior wood and trunk will receive intense sunlight. This intense sunlight increases the chance of sunburn to larger limbs and the trunk. This sunburn damage attracts boring insects (borers) to those locations.
Borer damage in purple leaf plum


For this reason, shade from the canopy on the interior wood of the plant is extremely important. Many woody plants in the rose family, which includes Pyracantha, are subject to damage from intense sunlight due to their thin outer bark.

Most of our fruit trees are also in the rose family and are subject to sun damage and borer
problems. Pruning should be pruned to maintain a moderately dense canopy. A canopy which is not so open provides filtered sunlight to the interior of the plant and reduces sun damage. You don't want it pitch black inside the canopy but you do want filtered light, not intense sunlight, for any length of time.

Honeysuckle is a good vine to use here. However, it tends to get woody at the bottom as it gets older. This woodiness at the base can be managed by pruning it correctly. Woodiness at the base is promoted when the vine is pruned only at the top. Several years of pruning the top results in an unattractive plant that is mostly wood without much foliage.

When pruning this plant this winter, instead focus pruning efforts on the area close to the soil surface. Find large stems originating from this area and remove one third of this older wood close to the ground. This removes a lot of plant material from the vine but promotes new growth from the pruned stems.

Limb dieback of peach due to borers

These types of pruning cuts encourage new growth from the base of the plant. Next winter remove one third more at the same location and you should be back on track and reversing the aging of this plant, making it more juvenile. Focus your pruning efforts closer to the ground.

Sunday, January 4, 2015

Can We Plant in December and January?

Q. We are re-doing our whole front yard and just finishing up the drip lines. Is it too late in the season to put in new plants now?  We are planning on lantana, society garlic, red yucca, Mexican bird of paradise, and some deer grass.

A. We have entered the coldest part of the winter now in Las Vegas. We can expect temperatures to reach anywhere from mid teens to mid-20's late in the night depending on where you live. All of the plants you mention, except red yucca, could be damaged if you plant now. Larger, cold hardy trees and shrubs would still be okay to plant. Wait until after the coldest period of winter has passed to plant, about the first to the second week of February.

After you plant you should consider applying mulch to the soil surface surrounding them just to give them a little bit more protection. Whenever you are planting trees and shrubs into residential soils you want to mix good quality compost in the backfill surrounding plant roots. Use an equal amount mixed with the backfill surrounding plant roots.

Which Is the Best Pomegranate Variety?

Q. Which varieties of pomegranate are good to grow in the Las Vegas area?

Wonderful pomegranate grown in  Las Vegas
A. Southern Nevada is a good pomegranate climate, similar to the climates where pomegranates originated in south central Asia, Persia, Pakistan, Afghanistan and India.In areas: or than this pomegranates can freeze back. In warm but humid climates pomegranates have disease problems that we never see.

In the United States we have a wide selection of pomegranates available to us that have been collected from throughout the world. Some of the newer selections may be cold sensitive in parts of our Valley. I would stay away from unknown varieties unless you want to experiment.
Beautiful yellow pomegranate with red arils grown in Tajikistan

For the most part, all of the pomegranates available commercially do well. Of course the flagship pomegranate variety is ‘Wonderful’ with its beautiful outer and inner ruby red color. In actuality pomegranates come in a wide range of colors from dark purple to nearly black all the way to lemon yellow and off-white.
Pomegranates come in a wide range of colors on the outside but the inside of the fruit can vary from dark red to pink to white and from seeded to nearly seedless (soft seeds)

You will not go wrong with varieties such as ‘Sweet’ or ‘Eversweet’. A local favorite, sometimes referred to as seedless is ‘Utah Sweet’, a selection from ‘Sweet’. A variety from the former Soviet Union receiving rave reviews is ‘Parfianka’.

Other varieties I have liked include ‘Sharps Velvet’, ‘Red Silk’, ‘Pink Satin’ and ‘Grenada’. One variety I have been less than thrilled about is ‘Ambrosia’, and early producer but no flavor. I have seen no winter damage on any of the varieties I mentioned above.

What Causes Leaf Browning in Lilac?

Q. Since late September my five foot lilac planted on the West side of the house has been showing signs of stress. The lilac made it through the summer fine and all green but has recently shown browning of the leaves despite continuing to bud.  I read that fertilizers are not recommended or necessary but I am tempted to try.

A. Both common and Persian lilac grow in our climate. They will not do well in a rock landscape. They prefer soils higher in organic matter. If they are surrounded by rock, they will begin to decline in about 3 to 5 years, leaves will begin to scorch, you may see some branch die back, leaf drop and a reduction or no flowering at all.

Some varieties of lilac perform better here than others such as the early bloomers. An old reliable common lilac is Lavender Lady hybrid one of the first low chill lilacs produced. This particular variety requires less chilling and blooms well here. Another variety to consider might be Excel which also have a lower chilling requirement and is a very early bloomer. I would proceed with caution on low chill, late bloomers such as Angel White, California Rose and Esther Staley unless someone has had a proven record of good blooms and color.

This could be a location problem. A Western exposure is too hot for it. It likes sunlight but not combined with intense heat. It is best to have it in a location protected from late afternoon sun.

But I totally disagree that lilac doesn't require fertilizer. It not only requires fertilizer once a year applied after blooming but, under desert conditions, benefits from compost or organic amendments added to the soil. Lilac will perform well with some unamended arid soils but our desert soils in Las Vegas are just too low in organic matter. Lilac likes a richer soil than unamended desert soils can provide. It likes compost, wood chips as a surface mulch and fertilizer.

Saturday, January 3, 2015

Can I Plant My Gift Hydrangea Outside?

Q. My kids sent me a hydrangea for the holidays.  I know I have to keep it as a houseplant.  When I lived in New York, mine were huge outdoors. What do I need to do keep them alive and thriving?

A. Hydrangeas are not meant for planting in our climate and soils. Hydrangeas given as gifts are like poinsettias; intended to be grown in greenhouses for a one-time gift event. But what the heck, give it a shot!
There are some varieties of hydrangeas that are more suitable for growing outdoors than others. Western Sunset Garden Book has recommended varieties you can try. If you are lucky enough to have gotten one of these varieties as a gift then you may have a fighting chance of keeping it alive.
They need a bright location on the north or east side with filtered light. Add compost to the soil at the time of planting. The plants need an organic surface mulch that decomposes, enriching the soil, such as wood chips. It should be fertilized with an acid fertilizer every 6 to 8 weeks.
If you want to go whole hog on this plant then get some aluminum sulfate and apply it to the soil when you plant and in early spring. Aluminum sulfate does a better job acidifying the soil than sulfur. Acidifying the soil helps keep the flowers of vibrant blue color.
You are fighting an uphill battle on this one but if you really want it to work you must spend time and money on this plant with soil preparation, mulch and specialized fertilizers such as aluminum sulfate.

Otherwise, I would not bother and enjoy it for what it was intended; a gift on a special occasion from loved ones.

What is Causing Citrus Leaves to Yellow?

Q. What is causing the leaves on my lemon tree to turn yellow?  This has been happening gradually all year.

Readers lemon leaves
A. Leaf yellowing of citrus is caused by any of these problems or in combination: high light intensity, micronutrient deficiency such as iron, irrigation and drainage problems and salinity. If the yellowing occurred during the winter and it was more of a bronze appearance then I would say it was due to winter cold.

Looking at the picture you sent, some of the leaves have leaf tip burn. That could be caused by salinity or a lack of water. It is possible it could also be too much water or poor drainage but I don't think this is the case unless you are watering it several times a week.
Without more information I am guessing it is a combination of high light intensity, micronutrient deficiency and possibly salts. If the leaves were more “bronzy” looking I might also conclude it could be high light intensity if it is in a location with lots of reflected light.
Yellowing of citrus leaves due to high light intensity

Flush salts from the soil. Apply a large volume of water to the irrigated area under the tree to flush salts that might be causing a problem. Do this two or three times over a period of a few days then revert back to normal irrigations.
Water no more than every ten days right now. Make sure the volume of water is sufficient to wet the soil 18 inches deep. When new growth resumes, resort to irrigating more often but this time of the year irrigating 10 days apart should be adequate.
Unkinown nutrient deficiency of citrus but probably manganese or iron. Since iron deficiency is common in the Las Vegas Valley the KISS principle tells us to treat for iron

If there is rock surrounding the tree, pull it a distance of 3 feet away from the trunk. If wood mulch surrounds the tree, you do not need to pull it back. Make sure wood mulch does not contact the trunk of young trees. Keep wood mulch 6 inches away from the trunk.
Next, apply iron chelate containing EDDHA beneath the tree in January near a source of water. Cover the iron chelate with wood mulch to keep it out of the sun or make sure it is placed beneath the soil surface.

Magnesium deficiency of citrus
Next February or after fruit set apply a normal amount of fertilizer. Organic fertilizers are best. You should see a change in the color of the new leaves next spring during growth.