Fruit Trees and the Benefits of Wood Mulch

Q. Could you provide me with a copy of the mulch trial you conducted on fruit trees several years ago? You randomly applied mulch to different fruit trees and grew some without mulch. I lost this information.

This is a picture of the mulch trial performed at the University Orchard in North Las Vegas. A variety of fruit trees were planted with and without 3 to 4 inches of wood mulch at their base. They were all watered and fertilized the same. Mulch was wood chips made from trees that were removed from residences. Mulch was donated by First Choice Tree Service.

A. I conducted this mulch trial in 2009 – 2011 with the First Choice Tree Service on bare root fruit trees planted in our desert soils according to my specifications using 50% compost mixed with raw desert soil in a volume to volume ratio.

Look at the change in soil color after a very short time when wet soil is covered with woodchip mulch. The wood chips "melt" into the soil with time, decomposing and adding nutrients, stimulating microorganisms and make a healthy environment for earthworms.

            Mulch is a layer or blanket applied to the surface of soil. Mulch can be made from wood, bark, rock, newspaper, cardboard or even plastic. But if this is applied to the surface of the soil and left undisturbed, it is considered mulch.

This is Redwood decorative bark mulch. Bark mulches do not provide the same nutrients as woodchip mulch which is much better. Would chip mulch is made from the entire tree, not just from the bark.

            A 50% mixture in a volume to volume ratio, means, for instance, a 5 gallon of compost mixed with a 5 gallon bucket of raw desert soil. In a few months of watering this results in a raw desert soil with less than 1% organic matter increasing to between five and 10%, not 50%. If you want to know why, attend some of my classes.

            Peaches, plums, pluots were planted in holes about 3 feet wide and deep enough to accommodate their roots and no deeper. The holes were not deeper than this because water added to planting holes drained water in less than six hours.

This fruit tree was covered with a layer of rock mulch about 2 inches deep. Organics that were added to the soil at the time of planting will be gone in 3 to 5 years. These organics will be replaced with a mineralized soil that has no organics in it, soil life is dying and water drainage is getting increasingly worse.

            Fruit trees were planted using a 50% (volume/volume) mixture of compost and raw desert soil. All fruit trees were staked the first growing season and pruned in the same fashion after planting. No fertilizer was applied except for phosphorus to the bottom of the planting hole at the time of planting.

            All fruit trees were watered the same using a 3 foot wide basin, 4 inches deep, filled with water. All trees were staked and surrounded by chicken wire to prevent rabbit damage.

Irrigation basins around fruit trees, if they are not being watered by drip irrigation, should be level, large enough to be half the size of their canopy and 3 to 4 inches deep. Irrigation basins must get larger as the tree gets larger to provide enough water to the tree.

            Half of the fruit trees were randomly mulched with a 4 to 6 inch layer of wood chips made from local trees removed from home landscapes locally by First Choice Tree Service. The other half of the fruit trees were surrounded by bare soil.

            Mulch was kept away from the tree trunks a distance of 12 inches. The mulch was made from a variety of local trees not including palm and mesquite.

Mulch like this with a variety of different types of wood, not 100% bark, makes a great addition to the surface of desert soils. Don't let this valuable commodity go to waste in our landfills.

            At the end of the first growing season, fruit trees surrounded by surface mulch were more than twice the size than those without surface mulch.

            This mulch is available for free on a serve your own basis from the University Orchard in North Las Vegas and made available to the Orchard by First Choice Tree Service. If you want a large volume delivered, contact First Choice Tree Service.

Desert Soils Need Organics Added!

Q. I'm planting new fruit trees this year. I've noticed there seems to be a consensus that backfilling should be done with only native soil, without any amendments. However, is there an exception in Las Vegas where the soil is exceptionally poor?

A. This does not apply to desert soils with extremely low organic matter content. Some desert soils are okay to plant in directly with few problems. Others are not. Your soil organic matter content should be about 5%. If it is lower than this, add organic content to the soil such as a good quality compost. 

This is the kind of desert soil we typically see in the Las Vegas Valley. This soil is very light brown and cannot be done dry with a shovel. You must use a pick. This soil has nearly no organics in it. To plant in the soil without adding organics is sheer disaster.Some people call this mistakenly "caliche'. It is not. It is a sandy loam with zero organics but digs like caliche if not amended.

Mix it with the soil taken from the planting hole OR bring in a soil mix and use that to fill the planting hole around the tree roots or container “ball” of roots. Be careful of adding too much organic content to the soil. This can work against the establishment of roots in the surrounding soil. 

This soil is in a valley in northern Arizona. It is also light brown and extremely hard to dig. But the soil is very productive once it has been reclaimed with organics and water. It is also a sandy loam with virtually no rocks, a perfect soil for crops once it is been reclaimed.

This is the situation with research done in Oklahoma, Arizona and other states. These practices of “not adding organic matter” to the soil at planting is from their research with soils significantly high in organic matter.

This is the orchard in North Las Vegas covered with wood chip mulch 4 to 6 inches deep. The wood chips come from trees that would normally be taken to the landfill. If these trees are chipped and applied to the surface of the soil where there is water, the soil becomes dark brown in less than one growing season. Remarkably, we even find worms.

Many soils of the Mojave Desert with very low rainfall are extremely low in organics. Soils in the desert that are relatively high in rainfall or were previously farm land (under irrigation). These are frequently already high enough in organics and adding more does little, if any, good. Using the deserts of the Southwest as an example (Sonoran, Mojave, Chihuhuan, Great Basin) they range in historical rainfall from 4 inches to over 10 inches of rainfall each year. This is a 250% difference depending on locale!!! Of course we will see different types of plants and a difference in plant density and canopy size when we compare desert environments with a difference in rainfall of 250%!!! This is reflected in soil differences there as well. We see differences in organic content, salts, pH, etc.

The Sonoran Desert is different from the Mojave Desert primarily because it receives 250% more rainfall. This rainfall leads to a higher density of plants, plants which become larger and are different from the plants in the Mojave Desert. The presence of plant life and rain lead to higher organics in the soil which also contributes to better plant growth. The Mojave is really a desert!

How do we know what the organic content of a soil is?

We can send it to a soil testing laboratory and spend maybe $75 to $100 and wait for three weeks for a reply or use our noggin and get a rough approximation. The soil testing lab will give you a precise amount in the sample sent to them. If the sample sent to them is representative of the soil that interests us, the it may be fairly accurate. But, garbage in, garbage out. If the sample is NOT a good representative of the soil that interests us then it is garbage.

Rich, productive soils are dark brown in color, not light tan. The presence of organics in soils turn light tan soils into dark brown soils. Adding 50% organics such as compost to a desert soil does not result in 50% organic matter content. It will probably be somewhere around 5 to 10% when it's all done.

Look at the soil.

Soil color is a pretty good indicator of soil organic content. Rich soils, full of organics are brown to black. The lighter the color, the less organics in it. If the soil is moist and dark brown, you probably don’t have to add anything. If it is light tan or very light colored, even when moist, it probably needs organics added despite the recommendations from Oklahoma or Arizona.

This is a true desert soil, so low in organics that its color is almost white. What to do? Add organics, in this case in the form of compost or manure. Mix it all together and water it. To get a really productive soil you will continue to do this for the next 2 to 3 years. The soil will settle down and start giving you big benefits.

Dig in the soil.

If you need a pick to dig or a shovel barely scrapes the surface, AND it is light colored….ADD ORGANICS!!!! Add organics in a ratio of about 1:1 by volume or container. Add a five gallon bucket of compost to this cement-like soil. Adding organics/compost in a 1:1 ratio (v/v) will NOT result in 50% organic matter content but probably in about 3 to 5% content after watering, settling, and growing for one season. Next year add 25% by volume (v/v) if it is a garden soil or apply about one inch of compost to the soil surface around a plant and lightly scratch it into the soil surface, and water it in. Keep compost at least (approximately) 6 to 12 inches from the “trunk” or stem of the plant. Beginning the third year, add compost around the tree/plant at the beginning of its growth cycle primarily for nutrients and improved biological activity.

Add organics to the soil when planting anything in our desert. Smaller amounts of organics are needed for lawns, a moderate amount is needed for trees and shrubs but a high amount is needed for vegetable and herb production.

Las Vegas soils, most of them, are extremely low in organics. ADD compost to these soils at the time of planting fruit trees, ornamental rees and shrubs. You have one time to do it and after that it is very hard to do if not done at planting time.

When to Stop Cutting Asparagus

Q. When should you stop cutting asparagus? We've had a good crop again but seem to have quit harvesting too soon in prior years so want to go as long as possible, we enjoy eating it!

Asparagus is harvested or cut just above the soil surface. It is best not to leave the severed spears too far above the soil surface or it gets in the way of weeding and other management practices. Cutting below the soil surface allows diseases to enter the plant.

A. The textbook answer is 6 to 8 weeks of cutting and then you should let it go and rebuild its crowns beneath the soil for next year’s harvest. That information was back when asparagus spears were thought to be marketable only if they were the diameter of your thumb.

Three grades of asparagus based on diameter of the spear. The highest quality asparagus has spears large in diameter. The smaller diameter asparagus is becoming popular as a lower-cost alternative. Asparagus produces a lot more small spears than the largest ones.

            That’s kind of changed and now we see asparagus much smaller than that and marketed as such. The other answer is to continue to harvest until you see a noticeable decrease in the diameter size of the spears. When they start to get too small for harvesting, stop and let the beneath ground part of asparagus rebuild itself.

When planting asparagus the crowns are planted 12 to 18 inches apart and 8 to 10 inches deep. I like to plant them on either side of drip tape or drip tubing in a triangular pattern with rows that are wide enough to walk between and harvest.

            Asparagus will rebuild itself better if you can provide some nutrients as the crowns are putting away storage for next year. So after harvesting, laid down at least an inch of rich compost or you can also use manure.

Purple asparagus is a novelty which brings a little higher income but purple varieties do not produce as many spears. They have a higher sugar content and are a bit sweeter than the green types. I stick with varieties that have done well in the hot Southwest such as the University of California or UC types. Purple Passion has done well for me.

            The crowns should be 6 to 10 inches deep depending on the soil so laying manure on top of these areas should cause no problems. Make sure you water it in and don’t water too often because the crowns are fairly deep. Put them on a similar irrigation cycle to fruit trees if they are planted deep.

My New Sod Lawn Never Grew But Died

Q. About three weeks ago I laid tall fescue sod in my backyard.  I put some top soil under it for a base before I laid it.  I religiously watered the sod twice a day. Today I removed the sod because it was all dead. No roots emerged. Where did I do wrong?

A. I am not sure you did anything wrong. If you kept the sod wet after it was delivered and planted it right away, it should have grown.

Sod comes either rolled like this or in flat rectangular strips. Make sure the sod was recently harvested and kept moist. It should be placed in the shade until it is planted. I would never buy fescue sod during the summer months. Warm season sod such as Bermuda, paspallum, zoysia, buffalo or St. Augustine could be purchased during summer months.

            I have seen problems with sod when it was laid on very hot ground. During the middle of summer, bare soil can be 165 to 170° F, hot enough to “cook” the roots of grasses laid on top of it. If you spray Roundup on bare soil, wait 7 to 10 days before laying sod or planting seed because this chemical can damage it.

This sod was laid on hot, dry soil during the middle of summer and not watered until after all of it was installed. The hot, dry soil seared the roots of this sod and caused it to die in patches.

            If soil temperatures are hot, lay the sod during very early morning hours. If it must be done during the heat, lightly spray the soil with water just ahead of where you are laying it. The spray of water helps cool the soil as you’re laying it. The downside is the soil can get quite muddy.

            The best time to plant fescue seed is from the middle of February until about May 1 and then again from mid-September until middle November. With sod, extend the season a couple of weeks longer in the spring and later into the fall.

Fescue sod is sometimes grown with plastic netting and a very thin layer of soil. The sod is held together by the plastic netting which makes it very light. Sod roles can be huge and installed much like a carpet when sold this way.

            Topsoil put down for sod should be at least 6 inches deep or more. Another option is to apply 100% compost, 1 inch deep, and rototill it into the soil as deep as you can. Roll the soil before laying the sod. After laying sod, roll it again with a water roller or steel drum roller after it has been irrigated two or three times. Rolling it and keeping the soil wet helps to “knit” the sod into the soil beneath it.

When installing sod make sure that the seams, where the sod comes together, has no gaps in it. It is always a good idea to water the sod as it is being installed and then roll it so that the roots and soil make good contact.

            Pull on the sod after two weeks and see if it is staring to “knit” into the soil beneath it.

Knitting is growing roots into the soil from the sod. If it is knitting, then water less often but water it longer.

Did You Know African Sumac Has Boy and Girl Problems?

Q. I have two similar African Sumac trees. One faces north the other south.  Both are about the same age, watered and fertilized the same. The south tree almost continually puts out ground shoots while the north tree seldom does. Any ideas why?

African sumac is a cute little tree when it's small and placed close to a home. It should never be this close. Place it no closer than eight feet to the home. This tree has too many stems. Remove all of them except for three or five, never four. Odd numbers are more pleasing to the eye then even numbers.

A. Put African sumac trees in the same category as mulberry and many of our ash trees regarding their sexuality. African sumac has separate male flowers and female flowers and they grow on separate trees. This means that some trees are male, and some trees are female. The female trees are the problem.

African sumac flowers emerge during the winter months because the tree originates in the southern hemisphere. Flowers can be male or female. Trees can be male or female. Male trees do cause some allergy problems. Female trees drop their seeds on the ground and can be invasive.

            Female trees produce seed. Seed drops to the ground and germinates easily everywhere. They also produce suckers so they can sucker from the soil as well as spread their seeds. Birds like to eat these seeds so they help in dispersing them.

African sumac that is 8 to 10 years old. It has a good shape for shade but it does have some problems. A number of people who have planted them in the past have regretted it. Be careful and learn about this tree before buying it.

            African sumac is regarded as invasive in several states. In the desert, it can be invasive along natural waterways because the seed germinates easily. Nice-looking tree but I don’t care for it for these reasons.

Would of African sumac is not terribly hard and can split under a snow load when the leaves are present. They can also be quite messy.

Getting Rid of the White Fuzzy's on Cactus

Q. I have cacti that attract the red insect that covers it with the white cotton like substance. Would it help if I cleaned them off and then sprayed the cactus with Volck oil?

A. This is a red cochineal scale insect causing this white, cotton -like substance. They live under this cottony mass, sucking plant juices from the cactus and protected by their cottony house. If you push on this cottony mass with your finger, the insect leaves a red dye on your fingertip.

            I used to spray cactus with a sweep nozzle on the end of a hose to knock off the white cottony stuff. It works but during the warm summers they are back infesting the cactus with their white cottony stuff in about one week. The secret to long-term control is knocking off the cottony stuff and then immediately spraying the cactus with a pesticide.

            Oils like Volck Supreme by Ortho or Neem oil works for a while after you knock off the cotton mass. But they will be back.

            I have not verified this but I heard that Volck Supreme oil has been discontinued by Ortho, the manufacturer. But that rumor has been floating around since 2014. Monterey and Bonide make good oils as well. All of them are insecticidal oils and kill insects by “smothering” them.

            If you apply oils during the summer, apply in the early morning when temperatures are cool. The label warns not to use it when temperatures are too high. Spraying oils during hot summer months can result in plant damage. Never spray plants with flowers that are open because of honeybees.    

            This insect will return so repeat sprays will required as these cottony masses begin to build again. There are other insecticides available giving better control but they have their downside so I hesitate to mention them. Try the oils first. Also try soap and water sprays.

How to Win the War on Weeds in Your Landscape

Q. People in this house before us had grass in the front and in the back. Before selling the property, they put plastic sheeting over the grass and rocks on top of that. The plastic, I think, is just keeping everything moist underneath it and the grass and weeds just keep on coming up.

Weeds growing in a desert landscape.. Developing a good landscape design that minimizes the wet areas in a landscape will help to control weeds.

A. Putting plastic under rock mulch is never a good idea. Think of it this way: plastic is temporary. Rock is permanent. Never put something temporary under something permanent.

            Putting temporary plastic mulch under permanent rock mulch always results in plastic emerging through the rocks at some time. This is unsightly, weeds emerge through holes in the plastic and the plastic eventually emerges through the rock. This requires the owner to pull the plastic out from under the rocks to keep it from becoming unsightly.

This is a black plastic that was put under the rock in a rock landscape. Sooner or later the black plastic develops holes and begins to tear or rip. When this happens it begins to emerge from the rock and becomes very unsightly.

            A more effective and permanent mulch under the rock is made from landscape fabrics. These fabrics are either woven or spun with tiny holes in them for air and water and have a long durability. They last a lot longer than plastic.

Nutgrass which is sometimes called nutsedge,
a very tough weed to destroy when it gets in your landscape.

            They are expensive compared with plastic. And landscape fabrics do not prevent Bermudagrass or nutgrass from coming through it, a couple of very tough weeds to control.

            Instead, put down a thicker layer of rock, 3 to 4 inches deep and no smaller than ½ inch minus. Over time, dirt accumulates in rock mulch and weeds grow in it but at least they will be easier to pull or kill.

One of the better hoes I have used in rock mulch is the Hula hoe, sometimes called a stirrup hoe or simply  scuffle hoe.

            The secret to good weed control is killing weeds as soon as you see them. During the first year, this requires weekly visits to your landscape and removing them with a hoe, pulling, using a fire weeder or chemicals. If pulling them, water the area first and pull them 30 minutes later. They are much easier to pull.

            The first time controlling weeds, knock them all down by hand, fire or with chemicals and remove any weeds with flowers or seedpods from the property. In one to two weeks, weeds will come back with a vengeance. Control these infested areas as soon you see them. The third week, other areas will emerge with weeds. Control them immediately as well. Do this persistently and weekly for the next 2 to 3 months, pulling or killing them as soon as they appear.

More black plastic emerging from underneath rock applied to the surface as a mulch. Never put a temporary mulch like plastic under a permanent mulch such as rock.

            In the second year, most of the weeds will be controlled. Just control the “hotspots”. By the third season, hotspots will appear occasionally and then control is needed only as weeds become problems. Yes, this sounds like a lot of work but most will be under control in 2 to 3 months and the work becomes easier.

            The mistake people make is diligence, staying on top of it. Once weeds become established, you lose the “war against weeds”.

Roundup aka Glyphosate Not Doing the Job

Q. This year has been the worst for weeds and grass coming up through the rocks. I’ve tried Bayer Advanced, All-in-one concentrate which acted like a fertilizer and strengthened their growth! I got Roundup weed and grass killer concentrate. Two weeks later and the grass is coming up like I planted it. What do you suggest I use to spray on this grass to kill it? 

Roundup is a proprietary name developed by Monsanto for the weed killer which contained the active ingredient Glyphosate. It was developed and did its best job killing grasses.

A. Roundup weedkiller is an excellent grass killer if applied properly. Please remember this weedkiller will not kill plants in less than a week. It needs at least seven days to take effect in warm weather and more days during cooler or cold-weather. You might see some yellowing or change to the leaves in fewer days than this. It depends on the plant.

There are other products now which contain the active ingredient Glyphosate and are essentially the same thing as Roundup but at a considerably lower price.

            Use the concentrated product rather than ready to use if you never used it before. The ready to use form is excellent if you used Roundup in the past, you know which weeds you are killing and how they will react to this weedkiller.

            When mixing this product read the directions carefully. The directions tell you how many ounces of water should be mixed with the concentrated product. If you never used this product before, use the highest number of ounces mixed in a gallon of water allowed on the label.

            Water the weeds with a hose to wash off any dirt. Dirt on the leaves can interfere with how well it works.

            Mow tall weeds or have them cut with a line trimmer before applying Roundup spray. The Roundup spray mixture must contact green leaves for it to be effective. Roundup does not enter through roots but through leaves so only use enough water to get the leaves wet.

            Don’t sprinkle irrigate for at least 12 hours after they are sprayed. Keep kids and pets out of the area for 48 hours. If you are not confident with this application, then hire someone or have a friend or neighbor apply it for you.

Note: there is a lot of controversy surrounding the weed killer called Roundup and its manufacturer Monsanto. It is not my job to tell you what chemicals you should be using ethically. Weed killers were developed so that manpower or labor could be reduced by professionals. However, I do believe it is best to use human labor to remove weeds whenever possible.

National Organic Program Alert on Fraudulent Organic Certificates

NOP Posts Fraudulent Organic Certificates 

The USDA Agricultural Marketing Service (AMS) National Organic Program (NOP) is alerting the organic trade about the presence of fraudulent organic certificates. Fraudulent organic certificates listing the following businesses are in use and have been reported to the NOP:

• Chia-Brand LLC
• Mult Blindagem LTDA  (Certificate No. 53540-12)
• Worldwide Wholesale Warehouse, Inc. (Certificate No. 51368-13)
• Supattra Import & Export Co., LTD
• Multi Purpose Trade Marketing PTY LTD
• Desert Harvest, Inc.
• Yunnan Dianhong Group Co. Ltd.

Review these and other fraudulent certificates online at: Fraudulent Organic Certificates.

These certificates falsely represent agricultural products as certified organic under the USDA organic regulations, violating the Organic Foods Production Act of 1990. Fraudulent certificates may have been created and used without the knowledge of the operator or the certifying agent named in the certificate. 

For more information on this subject Visit here