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Monday, June 23, 2014

Viragrow Delivers! : Pepper Leaves Curling. Bugs Again!

Viragrow Delivers! : Pepper Leaves Curling. Bugs Again!: Leaves curling on pepper. Typical pepper leaf curled on the plant. Flip leaf over and we see evidence of aphids feeding. We see ...

Sunday, June 22, 2014

Olive Tree Dropping Leaves, Leaves Yellowing

Q. I have an olive tree that is approximately 20 years old.  It loses leaves year round and in excess. Some leaves are yellow but most are green. It is planted in lawn. It is watered twice a day for a total of 10 minutes. What can I do to stop this excessive leaf loss?

A. Olive trees are evergreen so they will constantly lose leaves during the year. The heaviest leaf fall should be in the spring during new growth or during the winter if there is a hard freeze.
Not the readers olive tree.
            These trees are tremendously versatile and can withstand droughty conditions as well as fairly wet conditions. They can handle a wide range of soil types.
            They handle abusive pruning techniques. That is the main reason they are used here.
They are resilient and respond quickly after being damaged, either by humans or the environment, as long as they get enough water. Being planted in lawn, I would assume they are getting plenty of water.
            If the canopy of the tree is beginning to thin, it is because there is not enough new growth to replace the leaf drop. If the lawn is fescue in good condition and well-managed, it should be receiving plenty of water. If the lawn is bermudagrass, then that is a different story.
            Fescue lawns require frequent irrigations because of their shallow roots compared to trees. Olive trees are deeper rooted and require water less often but with higher volumes so the entire root system is irrigated. Growing in bermudagrass they might require supplemental water besides lawn irrigation.
root knot nematode on tree roots. this is mulberry but it will be similar.
            Olive trees growing in lawns usually develop roots closer to the soil surface than without grass because of the shallow lawn irrigations. I would not think leaf drop would be a big problem unless your soils stay wet between irrigations.
            Normally soils that stay wet are described as heavier soils and have a high percentage of clay. This should not be a problem in sandier soils.
            Olive trees have few pest problems but one that can cause excessive leaf drop and stunting of growth are nematodes. The usual nematode is the root knot nematode, the same one that damages many vegetables, fruit trees, ornamental trees and shrubs.
            The only way to find out if this little guy has invaded the roots of your tree is to dig down through the grass, find some olive roots, and inspect them for little knots or round balls growing along the length of one or two-year-old roots.
            Even if you find them there, there is nothing really you can do to get rid of them. The recommendation would be to fertilize and water the tree separately from the lawn to encourage more growth. More growth helps to cancel out the stunting effects from the nematodes.
            Have someone knowledgeable about pruning do some selective limb removal throughout the tree canopy. By removing some of the unnecessary limbs, more growth will be forced into the remaining limbs and will provide better light penetration into the canopy.

Reviving Crepe Myrtle After Neglect

Crepe myrtle with annual fertilizer applications
Q. I inherited an established crepe or crape myrtle tree when we moved into a bank-owned vacant home two years ago.  The landscaping was pretty distressed.  I replaced the rock mulch with bark and the drip system seems to be working fine.  The tips of the leaves are dry and brittle and it blooms very little.

A. You are probably going to have to give this crepe myrtle a jumpstart. It is good you put down a wood mulch with this type of tree. I hope this is wood and not bark mulch.
            Since it is summer now you want it to push some new growth so you can see the tree’s strengths. Fertilizer is okay to apply now to trees and shrubs.
            Use a normal tree and shrub fertilizer and apply it a foot or two away from the trunk and close to its source or sources of water. Water it in with a hose.
            Construct a moat or a doughnut around the trunk of the tree at least 4 feet in diameter and 4 inches tall. This is nothing more than an irrigation basin to hold water. Fill this basin with water from a hose once a week for the next four weeks. Let your irrigation system run normally during this time.
Crepe myrtle trunk and bark
            Let irrigations push the fertilizer into the root area of the soil over the next couple of weeks. At the same time, add an iron chelate along with the fertilizer. The best iron chelate is iron EDDHA. You can find it in most nurseries now.
            When the weather cools off in the fall, around September, spray the foliage with Miracle Gro fertilizer used for the promotion of flowering. Try using a hose end fertilizer applicator so you can get it to spray that high.
            If you can't spray that high, apply it to the soil and water it in.
            Next spring start pruning out the deadwood in the canopy. Don't climb in the tree, but rather I would use a ladder. This is time-consuming because you will be cutting a lot of tiny branches along with some larger ones. Basically you are thinning out the canopy and getting rid of branches on top of each other or crossing each other.
            I question if your tree is getting enough water. If it is a sizeable tree it will require 30 or more gallons during each watering. You will have to look at your irrigation emitters and the time on your irrigation valve to figure this out.

Cut Lantana Back in February, Water and Fertilizer for Good Growth

Lantana regrowth when cut back to about 2 inches in February
Q. Why does Lantana grow and bloom with wild abandon everywhere but in my yard.  These plants are two years old and going nowhere.

A. Next February cut the stems of your Lantana back to about 1 1/2 inches from the ground. Fertilize the Lantana with a good quality fertilizer that promotes flowering (rose fertilizer is an example) and water it in lightly. That should take care of the problem.

Wood Mulches for Desert Soils are Remarkable

Desert soil typical of the Las Vegas valley with caliche
If you don't think wood mulch is important for tree growth in desert soils then you need to study this picture of fruit trees in their second year of growth. These are bareroot fruit trees, supplied all the same size, from Dave Wilson Nursery. Fruit and nut trees include plum, pluot, almond, peach and apple. All planted in the same manner in a typical desert soil in Las Vegas. The only difference was the application of wood mulch to the surface of the soil at the time of planting. Not bark mulch, wood mulch that was diverted from landfills and used as a mulch instead and supplied by a tree service company, First Choice Tree Service.

This is their second year of growth. The soil is classified as a sandy loam but hard as concrete because it lacked soil organic matter. The pH of the soil was right around 8. The salinity of the soil was over 40 mmhos or dS/m. Boron levels varied but about 8 ppm on an average. This soil was about as bad as any soil can get and still grow something. This is very typical of raw desert soils in the Las Vegas Valley.
Wood mulch in the orchard and improved soils

How it was done

Irrigation was installed using 2 gpm bubblers. Irrigation was bubbler and basin, with a six foot basin surrounding each tree. Holes were dug with picks and shovels four feet in diameter and deep enough only to accomodate the roots of the bareroot trees at planting time. All rocks larger than a baseball were removed and the soil taken from the hole was amended with an equal amount of dairy compost. Before planting all holes were leached to remove some salts with about 20 inches of water applied to each basin.

Trees were planted in late January into the basins and watered in as they were backfilled with amended soil. A starter fertilizer, about three pounds of 16-20-0, was mixed with the backfill at the time of planting. All trees were watered thoroughly as they were being planted to remove air pockets. Trees were staked and rabbit protection was provided to the trunks as either paper guards or wire screening. A basin was constructed around each tree and included the 2 gpm bubbler. Basins were about four feet wide.
Soil under mulch after three years of tree growth and irrigations

Finally a coarse wood mulch, coming from freshly chipped landscape trees in the valley, was applied to a depth of four inches in the basin of half of the trees. Orchard aisles were also covered in wood mulch between trees that were mulched. The trees grew for one complete season with and without wood mulch. This picture was taken two months into the growing season of the second year.

Why Do My Oleanders Have Yellow Leaves and Dropping?

Q. I also have questions regarding watering Oleanders (see attached pics). I have 2 separate hedges I'm currently grooming and both are in full sun exposure for about 6 hrs. My lawn currently waters them for 15 min. per day and they also each have 2 drip feeders at a rate of 2 gph each for 15 min. 3 times per day. The issue I'm having is the leaves are yellowing rapidly and appears to be worsening as the months go on. I did fertilize them this spring with 2 tbs of chelated iron to the soil and 1 tbs of liquid magnesium per bush. Did I over fertilize? I'm hoping this issue is not series as in leaf scorch.

A. Most of the problems on your oleander appear to be from the older growth and shading. I would prune them differently. I would remove one or two of the largest stems from the base of each plant, not prune at the top. You would do this next February, just before new growth. You will see new growth coming from the base and where the cuts are and in places where it receives light. Every year or every 2 or 3 years you will do the same to encourage new succulent growth from the base. Continually pruning at the top of the plants, hedging, will create big old wood at the base with no leaves. As the wood gets older, it drops its leaves. If you want to have leaves, you have to continually renew young growth from the bottom.

Why Are My Limes So Hard?

Q. Please tell me why our 12 year old lime tree only ever gets hard limes. They have never softened up. We grow them in the desert.

A. I don’t know which lime you have and there is no reason that would be obvious why limes would not ripen in a desert climate. The biggest problems with lime is its sensitivity to cold or freeze damage. If that doesn’t happen, then it should be fine as it is grown in warm desert spots throughout the desert Southwest.

The Mexican lime does not ripen until September or possibly early October. The Bearss or Persian lime ripens in June or possibly early July. 

Usually when we talk about limes it is the smaller Mexican lime we refer to in home yards. The limes in the grocery store are a larger lime, oftentimes nearly seedless, and it is the Bearss, Persian or Tahiti lime. The Key lime is more tart than the Bearss lime. Persian lime is a bit easier to grow and pick because it is relatively thornless compared to other limes.

Commercially limes are picked when their background color turns from dark green to a lighter green. The Persian lime will turn yellow when ripe, so yellow they can be confused with a lemon because of their larger size and yellow color. Pick them before they fall off the tree but when they soften a bit when you squeeze them.

So I am thinking you are picking too early. Wait until they start to fall from the tree this time, mark your calendar and next year work backwards from that date and pick them about two weeks prior.

Euryops Daisy Can Get Leggy and What to do About it

Q. I have a daisy bush that during winter lost all the lower greenery. Should I cut this way back to make the bush look full again, & when etc.  All help appreciated !
A. Looks like it is a Euryops daisy. Those are tough because they get leggy with lots of bare wood. It is best to not get it get leggy by cutting it back in late spring (February or March) and get it to grow from these cut ends. 

Remove about one-third of the growth. It will make a more rounded shrub that way with a tighter, more compact form and lots more flowers. You are growing a flowering shrub so don’t forget to fertilize it every six weeks through the growing season. 

You can also cut it back lightly as the flowers finish blossoming. You would do this by cutting off the spent flowers along with several inches of stem., It will produce two or three flowering stems at the point where each stem was cut.

Growing Green Tea in the Hot Desert

Q. I live in Henderson and would like the challenge of growing Camelia sinensis var. sinensis (common name Tea Plant) here in the desert.  I am willing to put in the work if it means I can grow and brew fresh green tea from my own garden.  Do you have any thoughts or resources that you know of that I might be able to do more of my own research?  I am confident that anything can be grown in Southern Nevada with the proper care.

A. Growing tea will be a challenge but it can be done here. It is grown commercially in South Carolina and Alabama (mostly black oolong and green tea) at a similar latitude to Las Vegas. The problems you will face include soil improvement, protection from winter cold, protection from damaging winds, low humidity and high light intensities. It can handle the high temperatures if it gets some light shade and protection from late afternoon sun (after about 2pm). 

It goes without saying that the soil will have to be heavily amended with organic matter such as good quality composts. Tea can be watered with drip irrigation. Tea can be started from seed or cuttings. You could grow from seed, evaluate the plants that are productive separately and then take cuttings from your best selections and propagate these.

Light shade would mean no more than about 30% shade. This can be done with shade cloth or lattice on top of the growing area. One method you might try is to plant along a cement block wall that is facing south. Put your shade cloth above the plants and have it extend about 30 inches beyond the plants to the south. This will help provide some light shade during the summer months but allow the winter sun to shine under the shade cloth due to the lower sun angle in the winter.

I would also construct some wind barriers to the outside of the plants so that wind is redirected away from them or the wind is slowed enough it limits the damage from torn and wind battered leaves. Improve the soil existing there by heavily composting that soil or grow them in raised beds using composted soil mix. Paint the block wall dark brown or black to absorb winter heat so it can radiate heat from the wall during the night in the winter.

As temperatures drop to near freezing at night (around the first or second week in December) cover the growing area in plastic and also attach a thermal blanket that you can drop over the plastic at night. I would not use just a thermal blanket. It might not be enough. Thermal blankets alone will only give you about 6 F of protection while using plastic and the blanket will give you a lot more protection.

In the morning draw the blanket up and allow sun to heat up the growing area. If it is a warm day (above 45F) you can open the plastic as well. If it is a particularly cold day (below 40F) I would leave the plastic on but vent it the best you can for a few hours when it is warmest. Then recover it again when temperatures start dropping again into the danger zone around 4 PM or later. In our climate these types of days are rare.

In plastic protected culture of plants it is important to provide temperature control, control of humidity, control of wind and ventilation to exhaust the “bad” air during the night. This helps to prevent disease problems.

You will harvest the new growth, 2 to 3 leaves, and dry them carefully and not in full sun here or with high temperatures. Dry them outside in a shady location. One pound of leaves will produce about 1/4 pound of dried tea.

Small Front Yard Tree Not Messy

Q. I want to plant a tree in my front yard where it gets southern exposure sun and space is approximately 9 feet from house where it will be planted.  I want something that does not get over approximately 20 ft. at maturity, does not drop fruit, seed pods or anything messy, and is drought tolerant.  I was considering a Western/Mexican redbud, Hawthorne, Raywood Ash.  What do you know of these trees?  Do you have any better recommendations based on my needs?

A. Here are a few notes on the trees you mentioned from Andrea Meckley:

Western Redbud - litter form leaves in the fall (plant is deciduous) and spring flowers  Multi-trunked so not a good shade tree.  15' wide x 13' high at maturity meets goals.

Hawthorn - I assume you refer to "Majestic Beauty' Hawthorn Patio tree-Evergreen with little leaf drop and April flowers that are not much of problem.  Prefers morning sun, not southern exposure.  Matures at 20'h x 8'w although I have not seen much larger than about 10' high in the Las Vegas area.

Raywood Ash - Leaf litter in late winter because tree is deciduous.  Matures at 30' h x 20' w.

Here are a couple of trees to look at with your requirements.  
With the information you gave, the Mulga Acacia (Acacia aneura) sounds like the one I would suggest.

Mulga Acacia - Evergreen with small spring flowers are not a big litter problem.  Matures at 20'h x 15'w.  Can be a shade tree with a ball head or lower branches kept on for more shade.  Hardy.   Considered 'bulletproof'  on the Southern Nevada Regional Coalition Plant List. 

Smoke Tree - Leaf debris (deciduous) in late fall.  Matures at 15' x 15'. Multi stemmed, so leave natural for more shade or prune for tree form.

From Andrea Meckley