Type your question here!

Thursday, August 31, 2017

Let's Talk @ RJ's Home Improvement and Backyard Expo Sept

Let's sit down and chat Sept 16 &17 from 11 am to 2 pm!

Pink Lady and Fuji Don't Need Pollenizers Here

Q. I planted a Pink Lady Apple and a Fuji apple together as pollination partners last March. My Fuji died over the summer. I like Fuji apples from the store but I'm wondering if I should try again with another Fuji tree or choose another variety?

A. Whoever told you Pink Lady apple tree needed a “pollination partner” in our climate is wrong. Pink Lady does not need one and neither does a Fuji apple. They are both self-fruitful here.
Fuji apples grown in North Las Vegas
            Stay with the Pink Lady apple. Pick a peach, apricot, plum or pluot to replace the dead Fuji apple. Don’t plant in the same hole but plant it a couple of feet away from the old hole. Amend the soil with compost at planting time.
Pink Lady apples grown in North Las Vegas
            Make sure apples are semi-dwarf. Don’t expect the same apple fruit attributes you have experienced before when fruit is grown in the desert. Different climates, soils and even rootstocks can change the flavor and texture attributes of fruit.
            Depending on the time of year, that Fuji apple you bought in the store was most likely a storage apple and not fresh. I like to smell fruit before buying it. When I walk past apples in the store, I want to be able to smell them as I pass by. I want to pick up a fruit, feel it and smell it before buying. Aroma is one indicator of freshness and not a storage apple. There are others.

Boomerang Lilac for the Desert. Yay or Nay?

Q. We love lilacs. My wife saw a new breed of lilac called ‘Boomerang’, a dark purple Syringa. What can you tell us about it? Can we plant it and can it survive? 

A. These 2 links to my blog might help.

            I do not know this lilac and I have never grown it in the Mojave Desert. All I can do is look at its description, the type of lilac it is and make some educated guesses. You can read about this lilac on the Monrovia Nursery website

            It has been touted as a dwarf, “re-Bloomer” which means it continually produces flowers all through the growing season and stays small which fits nicely into smaller residential landscapes.
            Reblooming lilacs are not new. But most of us think of lilacs that bloom only once for a couple of weeks and then it’s just a green bush the rest of the year until winter. Calling it “reblooming” is good for marketing.

Talk about Town

 Internet discussion groups say that the word re-Bloomer applied to this lilac is not very accurate. It does stay small, but people who have grown it say it’s more of a season-long “trickle of blooms” rather than reblooming over and over.
            I would not recommend planting this lilac in our hot, desert environment. First, it is not a Persian lilac, the type of lilac best suited for our hot desert climate. The breeding of “Boomerang” occurred in Canada and was intended for cold climates.
            If you decide to go ahead with this plant as your own personal experiment, locate it on the east or northeast side of the home in a place that protects it from afternoon and late afternoon sun. Let me know how it does.
            Amend the soil with compost at the time of planting and apply a surface mulch of woodchips to the soil that will continue to improve it, keep soil temperatures cooler and prevent the soil from drying too quickly.

Hibiscus, Star Jasmine, and Roses Same Damage

Q. This is a picture of my hibiscus leaf but my star jasmine and rose leaves have the same damage. Also, my hibiscus buds are falling off. I don't see any creatures. What do you think?
Hibiscus leaf with damage
A. When thinking about damage to leaves, the possibilities can be mind-boggling and confusing. The fact you tell me this same type of problem exists on the leaves of other plants usually means it is not a plant disease. If that is true, we can narrow down solutions to the problem better.
            Sun damage? When I first saw the damage to this leaf my first thought was “sun damage”. If this is an older leaf, then it could be damage caused weeks or months ago. If this damage is on newer leaves, then it is more recent damage and could still be going on.
            I am guessing this is damage to older leaves. I am guessing the damage occurred one or two weeks to a month ago, or perhaps even longer. The most important question is whether the newest leaves are showing this damage or not. If they are not, then the problem is gone and we are talking historically.
            If the problem is persisting on new leaves, then the problem still exists. Sticking my neck out somewhat, I think this may be an old watering problem during the very high temperatures of summer. If the younger leaves are not showing the same problems, then the plants were not getting enough water during the heat, but now are, since it's cooler and the need for water is less.
            If you have not done so, applying a 2 to 4-inch layer of woodchips to the surface of the soil helps during times of extreme heat and preventing this from happening.
            The issue of flower bud drop on hibiscus is usually water or temperature related; the soil is too dry or the air temperatures are too high. Woodchip surface mulch helps but make sure the plant is getting enough gallons of water each time it is watered. Growing it in bright, indirect light rather than full sunlight also helps.
            This plant may require adding another drip emitter. When temperatures begin cooling, you should start seeing flowers and less bud drop.

Make Sure Lawn Disease Is Actually a Disease

Q. I have never had fungus in my front or back lawn for decades. My front yard is good, but my backyard is absolutely horrid now. I had a clock problem but I never water during the night. I sprayed a fungicide and it did not help. Everyone tells me the fungus will always be there and continue to cause problems. I am concerned about the cost of continually buying and spraying fungicides in the future. 

A. Three problems cause lawns to fail; irrigation, disease and insects. By far, the majority of problems in the desert are irrigation problems. Without irrigation, lawns cannot exist. The reason for a lawn browning, however, can easily be misidentified.
            I follow a three-step process in lawn problem identification that relies on the elimination of problems in this order; insect, irrigation and finally disease.
            Insect problems are the easiest to identify between the three. Insect damage to a lawn may not follow any type of visual pattern because they usually involve some sort of “eating” of the roots, stems or leaves. Lightly pulling on damaged grass that neighbors dead areas usually reveals if it is insect damage.
            Irrigation. Browning of the lawn because of inadequate irrigation usually resembles the irrigation pattern. Identifying where the sprinkler heads are located, and then identifying the pattern of damage, oftentimes confirms if the damage is related to irrigation. Sometimes looking at individual blades of grass reveals tip burn or dieback from a lack of water.
            Disease. Browning from diseases may or may not follow a pattern depending on the disease and are the most difficult to identify. In the case of diseases, the only sure way is to send a sample to a pathologist but by the time you get the results it’s too late.
            Another way is to apply a fungicide. If the disease stops then it’s possible, but not always correct, the problem was caused by a disease. Browning of the grass caused by diseases can reveal some very interesting patterns when it is first starting. These patterns might be circular brown damage with a green center (frogeye) or in the shape of horseshoes, or no pattern at all.
            Looking for disease problems usually involves getting on your knees and looking at individual blades of grass growing closely to the brown area. Sometimes spotting or discoloration of individual blades of grass may indicate the presence of a disease.
            In any case, spraying a fungicide when insects or irrigation are the problem will not correct it. Go through this three-step method first before jumping to a conclusion about a disease problem and applying pesticides.

Artichokes and Those Nasty Little Black Bugs

Q. I contacted you earlier about my artichoke and tiny black bugs. I applied a solution of Garden Safe Neem Oil as a spray.  Hosed it down a couple times so cut off the top few inches of leaves.  No pests since then. The main plant is dying and there are several suckers growing.  I have been looking online for care of the plant.

A. Care for artichokes going in the desert is different from other locales. In my opinion, artichokes are very “dirty” plants. In other words, they have a lot of different insect and disease “issues”. The main problems I had was with aphids in the spring and whiteflies during the summer but all of them collecting on the bottoms of the leaves. I think this plant is dirtier than sunflowers!
Artichoke leaves at the base of the plant turning yellow because of aphids during the spring. Later whiteflies will become the major problem. You have to stay on top of spraying them if you going to keep them clean.You will find these critters on the undersides of the leaves.
            Those little black bugs were probably aphids. Aphids love artichokes! The problem with Neem Oil is the quality of the oil. Sometimes it works and sometimes it doesn’t. If you have found a good brand that works for you, stay with it.
            I also like insecticidal soap sprays for aphids. Both are nonselective so they kill just about every insect which is sprayed; good bugs as well as bad bugs so be careful where you apply them.
            Both of them usually require repeat applications a few days apart to keep levels of these pests manageable. Aphids don't like hot temperatures so their numbers decrease during the heat of the summer and are much easier to control then.
            Remove some of the artichoke leaves if they are too close together. Remove them at the base of the plant. This helps air to circulate around leaves which is important in disease prevention and insects are much easier to control.
            Artichoke plants don’t like the desert; temperatures are too high, the sunlight too intense and the soils are horrible. Artichoke plants look pretty bad during the summer months because of our desert climate. They perk up quite nicely in the fall and spring months.
            Do as much as you can to grow artichokes in an environment closer to their ideal; provide protection from the late afternoon sun, improve the soil with compost at planting time and apply organic mulch to the soil surface surrounding them. I have not done it, but I suspect they will perform better under about 30% shade.
            We eat their flower buds before they become flowers. For this reason, this plant benefits from a spring application of phosphorus just like tomatoes, roses, squash and cucumbers.

Xylosma Yellow Veins May Be Due To Lack of Nitrogen

Q. My xylosma bush leaves are dark green with yellow veins, the exact opposite of an iron shortage. I planted these from 5-gallon containers this past January. As the leaves get older, they become more yellow. What is the problem and what can I do
Leaf vein yellowing on xylosma

A. You are right, a lack of available iron commonly affects the color of leaves on newest growth. Mild iron chlorosis in plants is identified with yellowing leaves with their veins remaining a darker green. Newest leaves grown from the plant get yellower and yellower as the season progresses and the green color of the veins may disappear altogether.
            Sometimes the chlorosis is so severe the entire leaf, including the veins, become yellow and the edges of the leaves begin to scorch during hot weather. Besides leaf yellowing, shortages of iron appear always on the newest leaves while the older leaves remain darker green.

 Yellow Vein

            Green leaves with yellow veins has been reported in citrus, frequently grapefruit, and called “Yellow Vein”. I have not seen Yellow Vein on xylosma but there’s a first time for everything.
            In the 1950’s Yellow Vein was demonstrated to be from a lack of nitrogen. Applying high nitrogen fertilizers, like ammonium sulfate, corrected the problem in citrus the following year.
            Wood chips applied to the surface of the soil can also cause a shortage of nitrogen to growing plants if they are not fertilized. Other possibilities include chemical damage but probably no other plant nutrient besides nitrogen.
            What to do? Flush the soil around the roots with lots of water and then apply nitrogen fertilizers such as 21-0-0, compost or blood meal. Flushing the soil with water first might remove any chemicals present causing this problem.
            Apply a nitrogen fertilizer after flushing with water or the water could wash most of the nitrogen away. Apply high nitrogen fertilizers to the soil about 12 inches from the trunk and water it in. Follow label directions on the amount to use since it varies with each fertilizer and depending on its nitrogen content.

How Much of a Soil Base Does a New Lawn Need?

Q. We have a 200 square foot lawn that gets morning sun and late afternoon shade. The whole thing is brown now and I think it's because we overwatered it for the last few months. When we first put down the sod I don't know if we had a good enough base. How many inches of good soil should we should have above the hard stuff?

A. First things first. You cannot have a good lawn without a good irrigation system in our desert climate. Please be sure your irrigation system was designed and installed correctly.
            There is a lot of engineering that must be considered when designing an irrigation system. Make sure you have "head-to-head coverage" and your operating water pressure lies within guidelines of the sprinkler manufacturer. Select pop-up sprinklers that clear the surrounding grass at the maximum mowing height.
            Soil preparation is important before establishing lawn. But lawns have been successfully established on poor soils and the soil improved after lawn establishment. I don't recommend doing it this way but it can be done.
            It seems like no soil preparation before establishing the lawn would save money but it actually doesn’t. Inadequate or no soil preparation prior to planting makes a lawn difficult to manage, particularly during the summer months. Lawns established the “inexpensive way” are subject to more disease and irrigation problems.

             How to improve it after the lawn has been already planted? Irrigate the lawn and while the lawn is still moist, aerate it with a gasoline driven aerator. Stay away from sprinkler heads and hopefully the irrigation pipe was installed more than 4 inches deep or you’ll break the pipe.
            After punching holes with an aerator, apply a top dressing to the lawn and rake it into the holes followed by an irrigation. A good quality top dressing is screened to 1/8 inch minus and can be purchased from Viragrow in Las Vegas. It's the same top dressing used on golf courses. Do this once a year for the next 2 or 3 years in spring or fall and you will see a dramatic improvement IF the lawn has a good irrigation system.
            Don’t bag your lawn clippings. Recycle them back into the lawn. Most lawnmowers now are recycling mowers and chop the lawn grasses fine enough so there are no problems afterwards. If you have an older mower that is not a recycling mower, retrofit it with a mulching blade and mow the grass more slowly than you would normally. Don’t bag the clippings.
            Ideally, new lawns should have a 12 inch base of good soil. If that is not practical, then a 6 inch base would be the minimum. Removing that much soil and replacing it with good soil would be expensive and a lot of work.
            It would be better to mix a 1-inch layer of compost with your existing soil and mixing or tilling it in. No fertilizer is needed the first season after planting if a good quality compost is used.

Apricot Watering Can Lead to Lack of Drought Tolerance

Q. Most of the leaves on my apricot tree withered and turned brown. The same thing, to a lesser degree and later in the season, happened last year. But this spring it brought forth an abundance of blossoms, fresh, green and healthy-looking leaves and produced lots of good fruit. I checked the soil, and it is not dry, but slightly moist. I water daily on a drip system for 35 minutes. 
Apricot tree browning and losing its leaves every year. Probably running out of water as the temperatures get hotter.

Rock mulch is never a good idea surrounding fruit trees. Desert soils over time lose their organic content and this leads to poor drainage of the soil in the third fourth and fifth years after planting.

A. I looked at the pictures and 3 things come to mind when I read your question; daily watering, rock mulch and giving the tree enough water. I don't know how much water the tree is getting in 35 minutes but perhaps the tree is running out of water before the next irrigation.
            First, the rock mulch. I like rock mulch when it is used around desert plants. I don't like rock mulch used around non-desert plants such as fruit trees. You would help the tree by raking back the rock a distance of 3 or 4 feet from the tree and replacing it with 3 to 4 inches of wood chip mulch where there is water applied. Wood chip mulch is free from the University Orchard in North Las Vegas or Cooperative Extension just south of the airport.
            Daily watering of trees during the summer is never a good thing and can be tricky to manage. If you give the tree more water during an irrigation and then wait one day before the next irrigation, it would help the tree and perhaps eliminate this leaf drop. Perhaps more water could be added if there were more or higher gph drip emitters under the canopy.
            Apply water to at least half the area under the canopy of the tree. This may require more drip emitters than the tree has currently. A tree that size should have at least 5 to 6 drip emitters and would do better if there were more than that.
            Place emitters about 2 feet apart under the canopy and no closer than 12 – 18 inches from the trunk. A tree that size probably requires from 15 to 20 gallons every time it’s watered. If the tree is watered for 60 minutes and the tree has 6 drip emitters under its canopy, they must be 3 – 4 gallon per hour emitters. If watering for 30 minutes, use 5 gallon per hour emitters.

Be Careful How Juniper is Trimmed!

Q. My junipers are starting to die and turn yellow from the top. I water them twice a day; at 7:00am and 7:00 pm for 45:00 minutes. The nursery told me to water them every other day, 4 days a week, for 1 hour.What should I do to save them?
Junipers are not desert plants and may not fare very well over time when surrounded by rock mulch

A. I saw the pictures you sent. They appear to be sheared as well. Because of dense, internal shading due to their thick canopies, the "leaves" inside the canopy of these plants die and turn brown. It is only the outer perimeter of leaves that stay green. The inside stems aren't dead but the "leaves" or "needles" attached to them die and turn brown from a lack of light.
            When these plants are sheared, the dead, brown needles in the interior are revealed. Some junipers "re-sprout" from these brown, seemingly dead stems but others may not. However, new growth is slow when they “resprout”.
            Spider mites can also cause needles to brown and drop off. Don't assume your plant has spider mites unless you confirm their presence.
            I use a white piece of paper and "slap" a brown branches against the white piece of paper several times. This dislodges the spider mites from the needles onto the white piece of paper. By staring at the white piece of paper for 10 or 15 seconds, you can these tiny spider mites crawling around on it. You must look closely because they are the size of the period at the end of this sentence.
            Washing plants prone to spider mites once a month with a stiff stream of water removes surface dust from the needles or leaves. Removing the dust and dirt also helps control spider mite populations. Soap and water sprays also work if spider mite outbreaks are light.
            Junipers are notorious for dying if the soil is kept too wet. Their roots suffocate easily in wet soils. The first sign of overwatering is browning of the tips of the stems. This can be from soils that don't drain easily or when these soils are irrigated too often.
            Be careful of that. Juniper roots like to be on the dry side between irrigations. I think this is what the nursery was hinting at.
            It’s hard to judge how many minutes to give them but each of them should be fine if they receive 5 gallons of water each, distributed under their canopies. This would require at least 2 drip emitters but 3 would be better.

Watering Pomegranate Daily Works for Some

Q. Respectfully, au contraire, Mr. Morris regarding your advice to not water daily. I rescued my beautiful, full-grown pomegranate several years ago from certain death by daily watering, continuing to date.
Pomegranate rescued by watering every day

A. I realize your comment is not really a question but I want a chance to discuss it here. Yours is an exception. It depends on the soil, its drainage and how much water is applied. Daily watering can work under some circumstances and under these circumstances it might be the right thing to do. However, it can be dangerous to recommend it for plants particularly in our environment.
            Pomegranate is a drought tolerant fruit tree compared to most other fruit trees. You can search any posting on irrigation and pomegranate and all posts from knowledgeable growers will say the same. I would hate to tell people who to irrigate pomegranate based upon one person’s success.
            It is well known that shallow, frequent irrigation of woody plants, trees, shrubs and fruit trees for instance, cause the roots of plants to grow close to the surface of the soil where there is a good mixture of water and air. When plant roots grow close to the soil surface, they lose their potential tolerance to dry conditions or drought.
            If the soil surface is dry, the roots of plants will grow best at depths in the soil where roots find a happy balance between water and air. Allowing the soil surface to dry discourages roots from growing there but encourages them to grow deeper in the soil.
            Deep root growth provides a “buffer” during times of “drought stress” when water is not freely available. Deep root growth also provides a more stable plant during high winds or when they have a heavy fruit load.
            Sometimes watering this way does not seem to “pan out” but homeowners find that watering daily with shallow irrigations is easier for them. I agree that under rare circumstances, such as very sandy soils, shallow frequent irrigations are needed. But most of landscapes should not be watered this way.

Sissoo vs Ash for Landscapes

Q. We are considering planting Sissoo or Raywood Ash in our front patio which is covered with pavers. Are root problems a concern for Sissoo? I have concerns about dieback in Raywood ash because of diseases described in Northern California and Europe. Does our climate reduce the chances of disease problems? 

A. To me, the choice between Sissoo or Raywood ash is like picking between an apple and an orange; they don’t do the same job in the landscape. People choose Sissoo as a fast-growing personal shade tree while the Raywood ash is not fast-growing and is not much of a personal shade tree.
            Sissoo is much more likely to freeze during the winter here than Raywood ash. Because of their mature size, I don’t consider either one of them as good choices for a single-story residence in a desert climate.
            I observed a few Sissoo planted at homes in Las Vegas but most of what I know about this tree’s performance after planting is from homeowners in Arizona. The major complaints are its large size, limb breakage in strong winds, heaving of sidewalks and patios by its roots, general litter from leaves and fruit and root suckering throughout the landscape.
            Love it or hate it. There seems to be two opinions about this tree; people love it and others hate it. Not much in between. Homeowners who planted it in Las Vegas were surprised by its size and considered removing them after a few years.
            Raywood ash is not fast-growing like Sissoo but easily handles our winter temperatures without damage. But the trunk can be damaged by intense summer sunlight. It does not produce root suckers. Raywood ash is more “ornamental” with its beautiful fall color.
            Raywood ash is susceptible to a disorder, disease if you want to call it that, called Ash Decline. This disorder has been a problem in Las Vegas since the 1980s beginning with Modesto ash and later with Raywood ash. I generally don’t recommend planting ash trees susceptible to this disorder in the Las Vegas Valley.
            Both trees should not be planted in a desert landscape surrounded by rock. You’re asking for trouble if you do. Instead, plant them in lawns or surrounded by other plants that require moderate to high amounts of water.

Figs Eaten on Tree Could be Rats!

Q. Your advice has helped me get a couple of dozen figs off my relatively young trees this year.  However, the attached photos show where there were two figs a few days ago and now they are entirely eaten.  I have a net over them so I don’t think it’s birds and I cannot see bugs anywhere on the plant.

Figs eaten, possibly rats

A. Any animal that is an omnivore will eat figs. Birds usually peck at the fruit and it is obvious the remaining fruit was pecked apart by a bird. Birds get under netting unless it is tightly pinned to the ground. You can visualize where the bird landed on the branch and did its damage.
            June beetles are flying now and they will also devour figs. They seem to prefer yellow or white figs. However, the bird netting should keep them out. These insects will be gone in a couple of weeks and your tree will continue to produce fruit.
Pomegranate fruit definitely by rat
            Other critters, like rats, eat them ripe or unripe and leave exactly what you are seeing; the fruit entirely gone except it’s stem still attached to the tree. Look at where the fruit was eaten and ask yourself the question, “Is the branch strong enough to support the weight of a rat?” If the answer is yes, you know rats are in the area, it looks like a rat ate it then it probably did.
            Other possibilities include ground squirrels. They like to steal grapes when they are ripe and can climb trees as easily as rats. Ground squirrels will completely clean out almond trees overnight.

Drip Irrigation Fails Without Flushing

Q. I changed my drippers to adjustable types and have problems with them working in my backyard. I fix them either by adjusting or removing the heads. Now they work fine. This happens throughout the year but I have never seen so many fail at the same time. My front yard also uses adjustables but don’t have the same problems. I was thinking about going back to drippers for reliability. 
Variable flow or adjustable drip emitter above and below.Do you like to play Whack a Mole? If you do, then you will love adjustable chip emitters.

Close-up of an adjustable or variable drip emitter. I don't hate them but I don't like them very much and give precision drip irrigation a bad name.
These are precision drip emitters that met or release water at specific volumes over a given time, usually one hour. They are color-coded by the manufacturer to indicate how many liters or gallons per hour they release. The pointed end is pushed through a hole created by a punch specifically meant for drip tubing. Do not use a nail or Phillips screw driver to make these holes. Spend four dollars and buy a punch.I call these types of emitters "precision drip emitters" to differentiate them from variable drip emitters which are extremely imprecise in their delivery of water.
This is a flag-type precision drip emitter called so because of the triangular flag. The flag has a stem attached and can be removed from emitter for easy cleaning. I like them because they are so simple to use, inexpensive and easy to clean if they get plugged.
A. I call “dippers”, “drip emitters” or “emitters” but I think we are talking about the same thing. I work with drip irrigation all over the world. The major reason drip systems fail is because the system is not cleaned and “flushed” regularly. Flushing and cleaning drip systems must be part of a regular maintenance schedule.
            When cleaning and flushing a drip system, the primary filter or screen must be cleaned

Screen filter called a "Y-filter" because it's at an angle like the letter "Y".This black housing can be twisted open and inside there will be a screen filter which should be washed and flushed to remove sediment and debris. There is a round On the top which can be opened for flushing the inside of the screen but it does not remove everything.
thoroughly, every “dead end” must be opened and flushed with several gallons of water and emitters should be inspected for plugging when they are operating. If emitters are plugged, they must be cleaned or replaced if they cannot be cleaned.
The ends of polyethylene tubing or drip tubing can be bent over and this double ring device can be slipped over the end. This double ring keeps the tubing bent over to stop water flow but also allows the end of the tubing to be opened quickly and flushed to remove debris and sediment.Some people have used electrical tape to do the same thing but these are inexpensive and fast.
This is auto flush for drip irrigation. The double ring above must be open manually. This can be inserted inside the drip tubing and flushes the polyethylene pipe every time the valve comes on. I would still recommend flushing the lines manually periodically and after repairs but this helps reduce some of the labor.
            A major problem is created when drip systems are repaired and but not flushed afterwards to remove dirt that enters the drip lines. If drip irrigation lines are cut and repaired, I guarantee dirt entered these drip lines. It is mandatory that the “dead ends” associated with the repair are flushed immediately afterwards.
            Drip system filters are cleaned and the system flushed because dirt or sediment in the water collects inside the filters and eventually plug drip emitters. Flushing the irrigation lines removes algae and bacteria that plug emitters as well.
            How frequently to clean and flush a drip system depends on the quality of the water and how much water flows through the system. Irrigation systems should be flushed more often in summer than winter.
            How long it takes to flush and clean depends on the design of the system. Poorly designed drip systems take longer to flush and clean. When designing drip irrigation systems, minimize the number of “dead ends” so that flushing the system takes less time and there are fewer places that accumulate “dirt” and slime.
            Most drip irrigation systems attached to municipal water are flushed once a month if the municipal water delivered is clean. Sometimes it is, sometimes it isn’t, depending on the age of the municipal system.
            Even though filters must be installed as part of every drip system, small amounts of sediment pass through these filters and eventually become a problem if the system is not flushed and cleaned regularly. Failure of drip systems is gradual, not like an “on and off” switch.
            Drip systems attached to well water should be flushed more often because this water is “dirtier”. How often depends on the quality of the well water which varies from well to well. Typical cleaning and flushing might vary from weekly to biweekly during the summer months.
            Algae and bacteria (you might call it “slime”) grow inside every irrigation system. Algae and bacteria are not problems with most sprinkler systems but can be problems with drip emitters because the “emitter” holes are so small.
            In my opinion, drip irrigation systems must be flushed and filters cleaned on a regular basis depending on the quality of the water and the gallons used. The drip emitters used should be easy to clean and inexpensive. Variable drip emitters are inaccurate in their delivery of water but are subject to the same plugging as all other drip emitters.

Citrus Not For Every Backyard in Las Vegas

Q. Why does your list of recommended fruit trees have no citrus? I understand the problem with freezing during the winter but nurseries and garden centers here sell citrus. If I could provide some sort of wind block from cold winter winds and some frost protection, would lemons or oranges have a chance or are they just generally doomed? 

A. Generally, I do not recommend growing citrus in the Las Vegas Valley. Is citrus grown here? Yes, it is growing successfully in many backyards. So why don't I recommend growing citrus? Because many planted in our Valley die during freezing winter temperatures. Some don’t.
            Successfully growing citrus is better than a crapshoot. The overall climate of the Las Vegas Valley is too cold during the winter to recommend citrus. However, there are protected nooks and crannies in people's backyards that allow for citrus to be grown. These protected nooks and crannies are called microclimates.
            The major limitation for citrus here is cold winter temperatures. Cold winter temperatures are made more lethal when accompanied by strong winds. Remove these two obstacles and citrus does well.
            After an ideal microclimate is found, citrus must be healthy to survive our extremes of heat and cold. Amend the soil with compost at planting time. Do not apply citrus fertilizers after August 1. For long-term health of the tree, avoid surrounding it with rock and desert landscaping.
            And finally, choose fruit that you want combined with tolerance to freezing temperatures in your microclimate. Tolerance to winter temperatures is best with kumquat followed by mandarin orange, Myers lemon (only Myers) and grapefruit. Least tolerant to cold are the limes, true lemons like Ponderosa or Eureka and some of the specialty oranges.
            Planting citrus here is not for everyone. Proceed with caution and look at it as a fun experiment in gardening.

Removing Fruit from Citrus Can Benefit

Q. I have a 5-year-old orange tree and this year it has produced quite a bit of fruit. Many hang at the very end of branches and some are in clusters. I've read somewhere to prune these fruits However, I am not sure when to do that.  Do I prune them now?

A. Removing the fruit so that other fruit can become larger is a type of pruning called “thinning”. It is also done if the amount of fruit could break limbs or cause other fruit to be pushed off the tree.
            Thinning or removal of fruit from the limbs of fruit trees with a focus on increasing the size of the remaining fruit is done when the fruit is still very small. Usually about the size of your thumbnail. If the fruit becomes large before it is thinned not much benefit will be passed on to the remaining fruit.
            Some fruit trees are not thinned because removing fruit doesn’t seem to make much difference and increasing the size of the remaining fruit. This is the case with most nut trees, figs, pomegranates and citrus.
            Most citrus is not thinned so the remaining fruit becomes large. However, if the weight of this fruit threatens breakage of the limbs, then, of course fruit is removed to eliminate that possibility. It is best to remove the fruit early but if that is not done, remove the fruit as soon as you see the threat of limb breakage.Otherwise, support the limbs so they don't break and do some light pruning after harvest.