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Sunday, July 15, 2018

Goldenrain Tree Was Planted More in the Las Vegas Valley in Years Past

Q. I have a Goldenrain tree in a pot I got several years ago.  It’s about 10 feet high with a diameter of about 1.5 inches. What are the pros and cons of planting it in a desert landscape here in Las Vegas? What planting recommendations would you give?

A. I think it’s a good, nondesert tree. It is better suited growing further north than us but it handles dry arid environments very well. It is considered “drought tolerant” in Midwestern or California landscapes but it is not a desert tree. I would put it on an irrigation valve with other non-desert trees like most ash and pine trees.
            Because this tree has been left in its container for a few years, the roots will most likely be “rootbound”. There is not much you can do to correct this problem if it’s there. This tree may never fully establish in the landscape because of the circling roots inside the container.
            I have never seen it grown with rock mulch covering the soil surface but I don’t think it would be a good soil environment for it in years to come. It would, like most ash trees, grow better in soils covered in woodchip mulch.
            Even though it can handle a southern landscape exposure if it isn’t intensely hot, I would plant it on the east or north side of the home if possible. If that’s not possible, then surround it with other plants to keep it a bit cooler and the roots moist and give the roots somewhere to grow. The trunk sunburns easily so leave lower limbs on the tree until it gets older.  
            Because this is the Mojave Desert, plant this tree in soil mixed with compost. The soil should be dug three times wider than the container and the excavated soil should be mixed with compost when it is replanted. Be sure to run water from the hose as you are planting this tree to remove air pockets. Stake this tree upright for one growing season before they are removed.

Cactus Can Grow Too Fast if Given the Chance

Q. My cactus is falling over. I think I give then too much water.
Cactus falling over due to succulent growth from too much of everything

A. Rather than too much I think you are watering too often. There is a subtle difference. Let the soil dry more between irrigations. Other factors can contribute to this problem.
            The term “watering too much” has two different meetings; watering too often or giving the plant more water than it needs each time it’s watered. Both refer to “watering too much” but may produce two different results. Watering frequently damages plants that originate from environments where they don’t receive water frequently.
Cactus breaking due to its own weight and succulence
            If the soil dries between waterings and forces the cactus to use its own, stored “internal water”, then this will slow its growth. If the cactus is never forced to use its own internal water, the plant grows unchecked, using whatever water is available.
            Desert plants, including many cacti and succulents, are water “opportunists”. When water is present, they suck it up which feeds new growth. Frequent watering of cacti causes new growth to become “succulent”. This type of growth is easily damaged by wind or even by its own weight.
Cactus blowing over in the wind

            If the roots of these cacti are also restricted by the container, or water is applied close to its trunk, the top may get too large to support itself.  We say it is “top-heavy”. It is very likely to fall over or break during winds or heavy rain.
            Other factors can increase succulence. This includes fertilizing too often with high nitrogen fertilizers and not providing enough light.
            Provide your cactus a container or pot that is wide. It doesn’t have to be deep but water should drain from it soon after watering. Apply fertilizer once a year about one month before you expect it to bloom. Apply water when the soil is dry. When watering, you are telling it to grow.

Expect Mushrooms after a Rain in the Desert

Q. Mushrooms have sprung up overnight around some new daylilies we planted in a new raised bed. My husband thinks the soil the plants came in contained mushroom spores. We've never had mushrooms in our yard due to our dry air. Are these toxic? Will they hurt the plants?
Mushrooms popping up in some newly planted landscape plants

A. Don’t worry about mushrooms popping up in planted areas. This is quite normal, particularly after a rain, during periods of high humidity and particularly where there is shade. The potential for growing mushrooms exist anywhere dead wood can “rot” or decompose.
Mushrooms popping up in woodchip mulch after a rain
            Mushrooms pop up from soil mixed with woodchips, a thin layer of wood chip mulch on the surface of the soil, tree roots that have died, wood from construction that was buried and from the dead interior of trunks of even living trees.
Slime mold, another fruiting body of a fungus, popping up in a wet area of woodchip mulch
            Mushrooms are the sexual stage of many different fungi and easily identifies them as part of the “rotting process”. Sexual stage just means that these mushrooms release mushroom spores from the “caps” of the mushroom. The spores are moved about by air currents.
            A few fungi are “bad guys” and create plant diseases. Others are “good guys” and responsible for breaking down undecomposed wood into humus, compost or what might be called “black gold”. Your mushrooms are from “good guys”. But that doesn’t mean they are safe to eat!
            Most fungi that make mushrooms are classified as “saprophytes”. This term means they feed off only dead things, not living things. In other words, they are “decomposers” and not responsible for killing plants.
            Do not worry about these mushrooms harming your plants but I would still knock them over and let them rot so they aren’t accidentally eaten. Once knocked over, they will shrivel into nothing very quickly.
             Mushrooms oftentimes pop up after rains, during periods of high humidity, and disappear in two or three days when things dry out. The fungus network that created the mushrooms is still there, decomposing away, but does not send up any new mushrooms again unless there is rain or high humidity and plenty of wood to decompose.

Leaf Chewing Damage to Plants Present Special Problems

Q. We've noticed leaf damage this year on our rose bushes, apple and pear trees. More than previous years. But, peach, apricot, and pomegranate seem unaffected. Some of our roses were decimated. Any idea what pest causes this and how to control it?

Leaf damage from chewing insects. Very typical of  adult June beetle damage.

A. The picture of leaves you sent show uneven missing parts, many areas with parts missing down to the veins of the leaf.  This type of damage is from insects that have mouths specialized for chewing leaves. Heavy damage means there is a large population you have not seen in the past.
Typical June beetle
            Unless you see this type of damage throughout the year, there is no reason to spray chemicals now. Damage from these types of insects is probably over. Instead, concentrate on getting the plant producing replacement leaves. Let me explain why.
            Common insects that chew leaves include grasshoppers, many different types of beetles, weevils, and others. Some of these insects chew leaves throughout their entire lifecycle (e.g. grasshoppers) and others only during part of their lifecycle (most of beetles). Sometimes the damage progressively gets worse (grasshoppers and some weevils) and other times it lasts only two or three weeks and it’s gone (many beetles).
Metallic Green June Bettle
            Most of this type of damage that begins in summer lasts perhaps three weeks and stops. This is because the damaging stage of this insect is over. The lifecycle of this insect has moved to another stage of development and most likely will not be a problem. If you spray now, you wasted your money and time.
Grape fleabeetle
            When this type of damage suddenly occurs this time of year, it is usually from the adult stage of large insects like scarab beetles. They feed for two or three weeks before they die. An example are June beetles. Chewing damage from smaller beetles, like flea beetles, occurs earlier in late spring. Smaller insects like flea beetles can produce a second “crop” of adults so sometimes damage is seen in the fall as well. But the damage comes on fast and it’s over fast.
Grape fleabeetle damage
            Exceptions are grasshoppers where all stages of its lifecycle have chewing mouthparts. With insects like grasshoppers, we see leaf damage early in the season that progressively gets worse as the season wears on. Grasshopper control is best done as soon as possible if there have been problems in the past.
Probably root weevil damage
            Chemical pesticides reduce damage next year if you kill the chewing adults as soon as damage starts. If you wait until the damage is extensive, it’s too late. The leaf-damaging adults are gone, the damage has been done and have laid their eggs for next year.
            Instead, concentrate your efforts in rebuilding what was lost. Apply fertilizers to the soil and water them in. During hot summer months, use half of the recommended rate on the bag or container. Apply it twice, four weeks apart. Avoid applying fertilizers after August 1 to plants that are tender during cold winter months.

Eliminate Fruit and Seed from Plants But not the Flowers

Q. I have some trees and shrubs that produce fruit and seed I don’t want. Can I spray them and eliminate the fruit and seed? What’s the best spray use?

A. Probably the most popular fruit eliminator on the market is Florel. It is synthetic but mimics natural plant hormones.
            I have never used it for eliminating fruit on anything but olives. The label does allow you to use it on many other plants for fruit elimination. Read the label before you buy it.
            The problem with plants not listed on the label is knowing how much to mix in the spray. For this product to work, the flowers must be open and the spray must come in contact with the open flower. 
            Since flowers on trees open over a period of time, flowers on the top, south and west sides open first. Spray the tree twice to get good fruit control. Spray the plant when 20% of the flowers are open first and repeat the spray in one or two weeks when it is 80% of full bloom. It won’t give you 100% control but spraying twice increases how much of the fruit is controlled.
            I can’t tell you how many days to wait for the second spray because it varies with the weather. If temperatures are hot, flowering will finish in two weeks. If the weather is cool, the time of flowering could extend as long as 3 to 4 weeks. Play it by ear.

Use of Oregano Essential Oils to Control Food Spoilage

Essential oils (EO) have stood out for their potential application as antimicrobial agents, playing an important role in ensuring food quality and safety. In addition, the synergistic effect of EO blends can improve action spectrum for more effective applications. 

The purpose of this research was to evaluate the in vitro antimicrobial activity of oregano, sweet fennel, and cinnamon EOs, and their blends, against the pathogenic bacteria Escherichia coli and Staphylococcus aureus, and the fungus Penicillium spp. The antimicrobial activity was determined by the diskdiffusion method, at both microbial optimal growth temperature and refrigeration temperature. 

Different EO volumes were investigated, and an effective inhibition was observed for the concentration of 3 μL. Oregano EO has proven to be effective in all assays, when compared to the EO combinations.

International Food Research Journal 25(2): 540-544 (April 2018)

Go to the Journal Article