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Tuesday, July 25, 2017

Pomegranate Yellowing and Leaf Drop

Q. A combination of overwatering and this heat caused my 9-year-old dwarf pomegranate leaves to yellow and drop on about 1/3 of the plant.  I turned off the water and hand watering it with small amounts of water. The only thing I did differently was give the plants a small dose of MiracleGro in the spring. Any suggestions? 
This pomegranate does not look all that healthy. The leaves should be much darker green. Probably watering too often caused it and the dieback. Use more water and apply it less often. Let those roots breathe!

A. This is not your common ordinary disease problem. It is humanitis! And the fertilizer did not cause it either.

Pomegranate is remarkably resilient in our climate if it’s not watered too often. Avoid watering these plants daily. Give it plenty of water when you irrigate and then hold off until the next irrigation. I water newly planted trees this spring every other day when temperatures are above 110° F.
Here's a pomegranate yellowing. Why? Because it was planted in a lawn that needs watering every day.

Watering once a week is enough in early spring and late fall. As it gets warmer, water more often. You should never have to water more than once every other day in the hottest weather!
            Leaf yellowing and drop can be a temporary problem with many fruit trees regarding water issues. Give the plant some time to respond if these branches are still supple and bend easily. 
            If these branches have dried and appeared dead, cut them off just above healthy growth. I have removed damaged parts during the summer months and the plant re-grew without problems.
            Use wood chip mulch on the soil surface to help preserve soil moisture during the heat. This gives me one extra day between waterings. I am giving new plants about 5 gallons, 3-year-old trees about 10 gallons, 5-year-old trees about 15 gallons and trees over 8 years old from 20 to 30 gallons depending on their size. A dwarf, 9-year-old tree is going to be in the range of 10 to 15 gallons each time you water.
            I have had no problems with loss of leaves during the summer but some of the 20+ varieties I have grown had winter cold damage. Some varieties of pomegranates, particularly those with Russian names, showed some winter cold damage. Older, common varieties sold for many years in the American market sailed through cold winters down to 10° F.

Shrub Dieback Due to Excessive Heat and Lack of Water

Q. I have several really tall thick pittosporum plants - some well over 7 feet tall and usually thick with foliage, but this year they seem to have suffered a LOT from the heat.  I checked at the base and the most damaged one -- down to a mere skeleton -- is getting water.  They are about 20 years old -- is there an "age limit" to plants like these?
Thats a good looking full-sized Pittosporum with good leaf color. Obviously healthy.

Are they THAT heat sensitive?  I'd hate to lose them all.  When, and how severely, should I prune?  Take the more damaged ones back down to sticks and hope for recovery?

Drought on Pittosporum due to high temperatures and wind.

A. That is what a full-sized Pittosporum is supposed to look like. I like the color in the form of the undamaged plant. 

The damage top and suckering from the base tells me the plant is putting on some new growth where it is easiest for it. When everything is optimum, the plant will always try to get larger and put new growth as high as it can. When conditions are not optimum, then it will try to put on growth in places where it spends the least amount of energy and trouble. 
Sprouting occurred due to the cuts made on the stems and the stem exposure to sunlight combined with...thats an easy place for the plant to put on new growth. You remove something and it will try to regrow in that spot to get that energy from the sun.

The damage at the top in the suckering at the base tell me the plant is not getting enough water when it is watered. Plus it was opened up with some pruning cuts at the base. I would add 2 or 3 more drip emitters to the base of that plant and try to cover at least half of the ground under its canopy with water. This means spread the drip emitters out about 12 to 18 inches apart under its spread. 

I would also put about one bag of compost under the large plants and water it in with the hose. Keep the area wet for the following 1 to 2 weeks. I think you will see a change in 2 to 3 weeks. Prune out the dead branches by cutting at a Y or joint between the dead branch and a living branch deep inside the canopy, 8 to 10 inches inside of it.

Monday, July 24, 2017

Fiddleleaf Fig Care Prevents Diseases

Q. My fiddleleaf fig houseplant has brown spots on some of the leaves. I'm watering it every other week. I have looked but can't find the cause of these brown leaf spots. I thought it might be a fungal issue, so I applied liquid copper but that didn't make any difference. Do you have any idea what causes these spots and what I can do to help this houseplant?

I really appreciate it when I am sent so many pictures. This helps a lot in diagnosing the problem.Fiddleleaf fig, Ficus lyrata
A. Fiddle leaf fig has made a comeback. It used to be very popular 40 to 50 years ago. Now it’s on the rebound for interior designers as a houseplant.
            Fiddle leaf fig in the wild starts its life as an epiphyte, similar to orchids. Eventually they root into tropical soils and live their life as a small understory tree, strangling the mother tree. Which means it likes filtered and indirect light. It can tolerate periods of time without soil moisture as well.
            Brown spots on leaves can be a disease problem, particularly if they are closely associated with leaf veins. Plant diseases on houseplants are not common in desert environments because of our low interior humidity. 
            Insects feeding on these plants are a bigger problem. Inspect the plant for spider mites, scale insects, mealy bugs and fungus gnats living in the soil which can cause problems similar to diseases.
            Plant diseases are closely associated with the health of the plant. To improve its health, and ability to ward off diseases, make sure it gets adequate light, water and fertilizer. If you need to stake this plant so it stands upright in a container, it is a good indicator it has not been getting enough light in the past.
            Lack of light is a common problem for houseplants because of our dark interiors. Larger houseplants slowly decline, beginning around 6 months after they are plunged into dark interiors. Smaller plants decline more quickly. If they are large plants, they have enough stored food to live for several months before they decline.
            This plant requires placement near a bright window but not in direct sunlight. Once a month turn the plant so that different sides of the plant receive light.
            When temperatures are pleasant outside, place this tree in a sheltered area on the north or east side of the home under a tree. During this time, it can start building up its food reserves for that long, dark haul inside the home during summer months. Never place it in direct sunlight which damages the leaves and causes them to drop.
           Lift the container. It is dangerous to water on a schedule unless you are confident this schedule fits the needs of the plant. Watering of this plant can be withheld until the soil is quite dry. Instead, lift or tip the container to judge its water content. Water is heavy. Potting soil containing water is much heavier than dry soil.
            Use a pencil. Sticking the pointed end of a pencil in the potting soil can help judge the moisture content. Pencils slide into moist soil much easier than dry soils.
            User soil moisture meter. They cost about 10 bucks at any nursery or garden center. They are good for judging relative amounts of water but not exact amounts of water. This moisture meter will tell you if the soil is dry enough to water or if it’s still wet and should not be watered.
            Avoid using straight tap water. Our tap water has lots of salts in it. Instead, use distilled or reverse osmosis water and blended with tap water 1:1 or more dilute. Give it enough water so that one 4th of the applied water comes out the bottom. This helps remove salts.
            Add fertilizer based on the growth of the plant. If the plant is growing rapidly, temperatures are warm and there’s lots of light, water and fertilize more often. Add a small amount of fertilizer to the irrigation water at every 3rd or 4th watering.
            Interior plants should be repotted every 3 to 4 years. This means gently lifting the plant from its container and shaving off a 1 to 2 inch layer of soil from the root ball on all sides. Use a sharp, sanitized knife. Disinfect the container and repot the plant using new potting soil.

Apricot Leaves Dried-Up in Midsummer

Q. A few days ago I noticed that most of the leaves on my apricot tree had withered and turned brown. The same thing, to a lesser degree and later in the season, happened last year. But in the spring it brought forth an abundance of blossoms and 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 am watering daily on a drip system for 35 minutes. So, wondering if you have any idea what is causing this and if I should be concerned.

This is most likely NOT borer damage. Borers typically ravage a single limb. This is over most of the tree. That most likely puts the cause in the trunk, roots or soil.
A. I looked at the pictures and 3 things come to mind right away. These center around daily watering which is a no no, the rock mulch I see around the tree and the possibility that not enough water is being distributed to serve all the roots. I don't know how much water you are giving the tree but I think the tree is running out of water before the next irrigation. I also think the rock mulch under the tree is terribly hot.

First, is the rock mulch. I like rock mulch when it is used around desert plants. I don't like rock mulch very much when it is used around non-desert plants such as fruit trees. I think you would help the tree a lot if you could rake back the rock a distance of about 3 or 4 feet from the tree and put a layer of 3 to 4 inches of wood chip mulch instead. You can get this free in North Las Vegas from the University Orchard or from Cooperative extension just south of the airport.

Daily watering of trees during the summer is not a good thing. If you can apply more water to the trees and then wait one day before your next irrigation it would be helpful. Tree roots begin to suffocate when water is present in the soil all the time. Giving the soil a chance to dry and admit some air to the roots can be quite helpful to the tree.

When the tree is watered, water should be applied to at least half the area under the canopy of the tree. This may require you to add more drip emitters then you have. A tree that size should have at least 5 to 6 drip emitters and would do better if there were more than that. These emitters should be placed about 2 feet apart under the canopy and about 18 inches from the trunk. 

A tree that size probably requires about 15 to 20 gallons every time you water. This means if you have 6 drip emitters, they should be 3 gallon per hour emitters if you are watering for one hour. If you are watering for 30 minutes, you should use 5 gallon per hour emitters.

The Perfect Apricot Storm. Borers.

Q. During the past month of high heat one limb on our apricot tree appears to have died.  All the leaves on this limb dried up while the other leaves on the tree stayed green. The limb is about 1-1/2 inches in diameter near the base.  In addition to rough discolored bark there are a couple of amber-orange blobs of sap in this area of the limb (photos attached).
This borer infested limb can be replaced in three years or less in our climate and in production in three to four.

Any hope the limb will survive and recover next season? Should the limb be cut off now?  Could this be a disease that will spread to other limbs?

A. Paul. You have described perfectly the symptoms of boring insects (borers) in fruit tree. One limb dies while the others are healthy and frequently there is sap coming from the limb in blobs or round balls.
There's the little varmint! Under the thumb.

Take a sharp knife and remove the bark where you see the sap. If you are confident the limb is dead, remove all the bark down to where the limb is still alive. Cut the limb off in this area and hopefully the remaining stub will resprout with some suckers yet this year that can, eventually, replace the dead limb. With some TLC that can happen in three years or less.

This winter select three or four of these suckers as possible candidates to replace the dead limb. Next growing season you will make your final selection of one or two to replace the dead one.

No insecticides will do much good on these. The insect is most likely gone and the limb is dead. Cut and replace the dead limb with new growth.

Saturday, July 22, 2017

Desert Landscape Design is Combination of Art and Science

Q. We recently moved into a new single-story home and want low maintenance, desert hardy plants. The plan called for 4 Japanese Privet trees and we became suspicious. My husband and I know nothing about ANYTHING that grows and so went to Springs Preserve to ask questions. The designer there assured me they would be, "Just fine". The landscaping was completed at the end of March followed by horrific winds and the trees looked pretty battered but I figured that they would recover. But then...the heat!

Fast forward to now and we have one tree completely dead, two are looking rather ghastly and one seems to be okay. We are following the watering schedule outlined by the landscape company, 7 days a week, 2 times a day for 15 minutes each. 

We could use some guidance as to what happened and what my other possible plant choices could be?

A. You should have trusted your instincts. You're instinct was spot on when something didn't seem right to you. Let's see… You are putting in a desert landscape and using plants native to Japan... Are there deserts in Japan? Oh yes, the desert Japanese privet, I forgot about that one!

Again, I have to thank Sunset magazine for letting me use these pictures that appeared in that magazine over 20 years ago. I used them many times in classes that I taught over the years.This is an example of the Prof. Jones minioasis concept of desert landscape design. It emphasizes three watering zones; high, medium and low.

Of course, I'm joking with you and I hope you can appreciate a little humor at your expense. I have about 8 posts on my blog about using Japanese privet in landscapes in the Mojave Desert. About 4 or 5 of those are how they do not tolerate dry soils and they perform much better growing in lawns.

You did the best you could. You checked with who you thought were knowledgeable people and they assured you everything was going to be okay. Well, they were wrong.

A slide from a PowerPoint presentation I used in my classes.I am not a landscape architect nor am I landscape designer but my classes focus on water and energy conservation through exterior design.
I don't like to get involved in plant selection. It is my least favorite topic in horticulture. But the majority of these plants, and the most expensive plants on your plant palette, should come from dry climates not from places like Japan. I will forward this email to a knowledgeable person who loves this topic and she can respond to you.

But I would tell you this:

  • The first question a landscape designer should ask is what your activities are outside now and what might they be over the next 10 years. This lays the foundation for creating exterior livable spaces. Plant materials are secondary to the design and used to enhance these livable spaces.
  • Your landscape design should include a high, water use area, a medium water use area and a low water use area. The irrigation design reflects the landscape design and helps sustain the plants growing in it.
  • High water use areas are used to help lower energy costs such as for AC and to create pleasant environments for people to use these outside spaces.
  • High water use areas should concentrate on plants that shade your south and west walls. You do not need trees or plants that get above 20 feet tall for a single-story home. Plants much above that height just waste water.
Minioasis design concept and Hydro zoning rely on irrigation systems designed for plants having high, medium and low water requirements. Red is high, green is medium and blue is low.Again, thank you Sunset Magazine.

This type of landscape design concept is Dr. Warren Jones minioasis landscape design concept developed over 40 years ago at the University of Arizona in Tucson. It is talked about in his book, “Plants for Dry Climates”. This is still a valuable resource to use when deciding on a desert landscape design and plants to grow in it.

I attached some graphics for you to look at. I also included a finished desert landscape design that has a pool and lawn area. Yes, desert designs can be anything but should lower water costs, energy costs and use desert or desert adapted plant materials for the majority of its landscape.

Fruit Trees Don't Need Daily Watering in the Heat

Q. I bought this apricot tree in March and it flourished and I got lots of apricots from it within a couple months. It started to turn hot and the leaves started to turn brown I have watered it very well daily as it's exposed to full sun and it seems like it's withering and I can't figure out what's going on. Here is a few pictures of the whole tree and some of the leaves and even the bark

A. Avoid watering daily. Fruit trees do not need to be watered every day even if it's 115 F. I am watering hundreds of fruit trees that were planted in March of this year as bare root.  These trees were not in containers, and I am watering them every other day right now during this heat. But when they were planted, compost was mixed with the soil used for planting around the roots. As they were planted, water was added to the planting hole so that everything was a slurry, a muddy mess, all around the roots.

Apricot leaves will scorch more if the tree is not healthy. Make sure it's given an iron fertilizer in January or February.
Water with a hose during establishment. These trees were watered with a hose 3 or 4 times in one week before the drip irrigation was turned on. A depression 3 feet wide was put around each tree so that water from the hose would collect around the tree and the soil would settle around the roots.

Woodchip mulch. Finally, a 4 inch layer of wood chips surrounded each tree at least 3 feet in diameter. The woodchips were kept 6 inches away from the trunk so that water, in combination with the woodchips, did not rot the trunk where it entered the soil. These trees will not need to be fertilized for 2 years because of the compost used at planting time. You can get good compost from Viragrow in North Las Vegas.
Apricot tree may scorch when surrounded by rock on the surface of the soil when it is 115° F

Drainage. Take a post hole digger and create vertical holes or chimneys in the soil about 18 inches from the tree in 4 locations if drainage is a problem. These vertical holes will help drain water away from the roots and help prevent them from suffocating. Pour compost into these 4 holes and fill them. Then I would cover the soil around the tree with woodchips, not rocks, 4 inches deep. Keep the wood chips 6 inches from the trunk of the tree.

Monitor soil moisture. I would buy a soil moisture meter used for houseplants that will cost you less than $10 at Lowes or Home Depot. When you take a soil moisture reading, push the tip of the meter into the soil about 4 inches deep and look at the needle. Don't water the tree unless the needle is in the middle of the meter (5 on a 10 point scale).

Reader Not Sure What to Do with Aloe

Q. Not sure of what to do with this plant, Any suggestions?
A. Aloe doesn't like it in the same spot you might plant a cactus. It likes a little bit more protection from the sun and it also likes improved soils. I would plant it on the east side of a building or the south side if it's getting some filtered light. Northside is possible but there needs to be lots of reflected light. You can plant it in a desert landscape surrounded by rock but in a few years it might not grow very well, turn yellow and begin to dieback to the ground.

It's a succulent so you have to plant it and water it differently from a cactus. It will like more soil amendment such as compost mixed with the soil around its roots at the time of planting. You will have to water it about like a shrub growing in your yard, maybe twice a week or when you see it begin to shrivel.

Water and fertilizer. Because it is not a cactus, it should be watered and fertilized more often. I would fertilize it once or twice a year in the spring and early summer. It will respond very nicely to compost applied to the soil within 6 to 10 inches of the plant, no closer. Then water it in. Water it about every two weeks or when you see it start to shrivel.

Your Aloe vera can be propagated very easily by removing the soil around its roots and cutting off any new "starts" or pups with a sharp knife or pruning shears. If you don't do this every couple of years they will get overgrown.

They make good container plants but like I said you will have to take it out of the container every few years when it starts to get overgrown and divide it, cut off the pups for replanting. If you cut off the pups and lift them from the soil right away, put them in the shade for a day so the cut end has a chance to heal over. Don't plant it with a fresh cut.

You can also take a long sharp knife and cut the soil between the mother plant and the pup. Cutting through the soil will also cut the attachment to the mother plant. Do not lift it but leave it in the soil next to the mother plant for a few weeks. This will give the pup a chance to grow more of its own roots. Then go ahead and lift the pup with a long knife, pushing it up through the soil beneath from beneath it rather than only pulling it from the soil by its leaves. You can replant it in a container or new spot immediately.

As far as the health/medical benefits of aloe, It has a lot of uses. I think you will get a lot of comments from this post so stay tuned.

How to Produce More Flowers on Desert Lady's Slipper

Q. A long time ago I asked you for any details you might have for this somewhat gawky, but pretty plant, with its small red flowers come spring and summer.  Hummingbirds love them. The botanical name is: Pedilanthus macrocarpus. I am interested in trimming, feeding and any other details particularly to encourage more large blooms of the red flowers. We have two of these plants facing Southwest, and one is about 5 feet high and straggly.

A. I don't really know much about this plant. When I start investigating a plant, any plant whether I know it or not, I start digging for information usually from University documents and reliable nurseries. This plant has been given is "Lady's Slipper"And it is a perennial succulent.

This plant is from Baja and the Sonoran Desert. That tells me a lot. Yes it can tolerate desert soils and desert conditions but it does like to have a drink of water periodically. I also suspect this plant will grow better with a little bit of organics mixed in the soil at the time of planting. Or some organics added to the surface of the soil where there is water and let it decompose around the plant. It might also like to be misted periodically since it’s from Baja.

It seems to be tender to freezing temperatures below 30° F. It may not handle intense desert sunlight so it's best growing under trees in those exposures or on the east side of the building.

I couldn't find information on what triggers the flowering of this plant but information from Arizona State University says this plant blooms more profusely during the winter months. It remarks that summer flowers are not as striking. Flowering might be triggered by temperatures, daylength or rainfall.

So let's talk about how to get more flowers, and larger flowers, on this plant.

More flowers. The more growing points this plant has, the more flowers it will produce. Generally, pruning this plant to improve flower production should be done at its base; removing entire stems from deep down inside the plant rather than any kind of shearing or cutting off the terminal ends of the branches. 

Some of the longer stems can be cut back so that they will grow more stems to produce flowers. These are called "heading cuts". One heading cut will produce 3 to 4 new stems that can produce flowers.

Fertilizer. I believe in the use of compost for soil improvement and adding nutrients, fertilizer, for the plant growing in desert soils. Apply perhaps one quarter cubic foot of compost to the soil at the base of this plant in early spring. Try supplementing this plant with a high phosphorus mineral fertilizer such as triple super phosphate or bonemeal. 

Apply all fertilizers containing nitrogen in half rates the label states. Begin applying phosphorus fertilizers about two weeks before it is known to bloom. Do not apply any nitrogen fertilizers or compost after August 1 through November.

Sunlight. Make sure it has at least 8 hours of sunlight. Keep it out of spots where it has intense sunlight such as your walls facing West or South.

Water. Water it sparingly as you would a desert plant, but deeply when you do. Try watering once every 2 to 3 weeks. Use its growth as an indicator whether to water again. If it's not pushing a lot of new growth, water it more often. Apply water a distance from the plant equal to up to at least half of its height.

Drainage. This plant must have good drainage or it will die or fall over.