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Thursday, December 18, 2014

What to Do Before the Freeze Comes

We already had a taste of freezing weather back in November in some parts of the Valley. Unless this is a very unusual winter, more is coming. In Las Vegas we can expect nighttime temperatures to drop into the mid to high teens degrees F (-10C).

  • Rarely does the soil freeze more than a couple of inches deep. 
  • The coldest time is just before sunrise. 
  • Clear, cloudless nights will be more likely to give us freezing weather. 
  • If you think it might freeze, go outside at night and see if the night sky is clear (cloudless).
  • If you cover plants at night, uncover them the next day as soon as the temperatures are no longer freezing.
  • Water the day it may freeze or make sure the soil is wet going into freezing temperatures.

Check weather forecasts. Look for future minimum temperatures AND WIND!!!

I like Weather Underground for the wind reason and you can see it here and bookmark it.

Protect from the wind. Remember, cold is bad enough but when it is combined with wind it will be much more damaging. Protect anything of value or that can freeze and cause damage by first blocking the wind. This can be as simple as throwing a light blanket over a tender plant or a thick blanket around pipes that could freeze.

Wrap pipes totally. Remember that metal freezes quicker than plastic. Plastic pipes will freeze but any metal fittings exposed to the wind will freeze more quickly and be more expensive to replace. It is always best to wrap exposed pipes with insulation starting a couple of inches below ground. Wrap ALL exposed metal parts above ground. Leave nothing exposed to the wind.

Drain pipes. If the pipe and metal components don't contain any water, they are less likely to be damaged when there is a freeze. Drain pipes by opening irrigation valves after you shut off the water to your irrigation system. Shut off the water to the valves and loosen the bleed screw on top of the valve or loosen the solenoid 1 1/2  turns (not all the way!), enough so water squirts out from the solenoid or bleed screw.

Protect Tender Plants. A good resource on protecting plants from winter cold was published by the University of Arizona. You can find it here.

Plants that you should consider protecting at the first sign of a freeze include: limes, lemons (not Meyers), and citron, bougainvillea, many hibiscus, pygmy date palm, plants that are flowering. Don't cover plants with plastic. The cold plastic touching the leaves can damage them.

Mulch. Put a 3 to 4 inch layer on top of the soil surrounding the plants during the day when the soil is warm. Mulch helps trap soil heat and keep it from freezing. Plants that might freeze to the ground (Lantana) will have a couple of inches of stems protected from the cold and wind with a mulch.

Container Plants. Container plants should be moved into the garage or the plant+container should be covered all the way to the ground. Remove the cover when temperatures are no longer freezing.

Lawns. If the lawn has frost or is frozen, DON'T WALK ON IT. Walking on frozen grass will damage the blades and leave footrpints due to the damage.

If damage does occur..... do not prune out the damage until all cold weather has passed.



Damaged Cactus Edges Probably Rabbits

Q. I have a cactus that has small flat paddles with no visible needles. The problem it has is that all of the paddles seem like they are chewed around the edges. Every time a new paddle grows, the edge soon becomes brown around the edges.

A. This is most likely rabbit damage. Just because you don't see any needles doesn't mean they are not there. There are plenty of cacti that seem to have no needles at all. But they are small and even more of a problem for humans and other animals than cacti with large needles simply because you are not as cautious around these types.
Rabbit damage to nopal cactus with very tiny spines
One primary reason for having needles, and particularly large needles, is to prevent animals from eating the pads. The spines, or needles, on cacti are at locations on the plant which are not random. If you look at them closely they follow a spiral pattern with spaces between them.
Nopal Cactus with large spines
When a plant has large spines or needles it helps prevent the animal from getting close enough to take nibbles. The smaller the spines, the closer animals can get and chow down.

Rabbits love cacti with very small spines. They will eat between the spines being very careful not to let their mouth come in contact with them. Of course the easiest place for them to chow down is on the margins of the pads, between the spines.

You most likely have rabbit damage and you will have to exclude them from the plant if you want to keep them from getting damaged. Chicken wire in 24 inch widths with 1 inch hexagon openings will keep rabbits away from these plants if they are put around the perimeter. Make sure the rabbit cannot put its nose under the bottom edge and get under it.

What Are These Weird Growths in My Oleander?

Q. A backyard grouping of four, 12-foot high oleanders that are 18 years old have very strange growths sprouting from the branches so I sent you a picture. Some trees have dry branches.  Others show sections of normal-looking leaves. Meanwhile, a dozen other oleanders look normal. My initial thought was that the strange group of four was not getting the proper watering.  So I have been giving those some extra shots.  But haven't noticed much change since the extra watering started about six weeks ago.

Readers witches broom of Oleander
A. Those clusters of strange growth coming from the stems are most likely witches broom of oleander caused by a fungal disease. It is often spread by pruning shears from plant to plant. It can also spread within the same plant or passed on to new plants when propagated from cuttings.
Witches broom also causes leaf tips to die back but it is usually recognized by those clusters of shoots coming from buds below the pruned area. Usually these distorted shoots grow a few inches and then die.

You may not see these symptoms show up for a couple of months after pruning have been done. This disease is also spread by insects and rainy, windy weather.

There are no chemicals that will control this disease. I would recommend that you cut severely infected plants a few inches above the soil this winter and let them regrow from the base. Make sure you sanitize your pruning shears. If you have some plants there are showing some leaf tip burn then cut these back at least 12 inches below the area showing these symptoms.

Do you want to read more about whitches broom? Click on this link.

Where to Plant Pear, Apple, Quince and Citrus

Q. I'm thinking about adding pear, apple, quince, grapefruit and blood oranges to my landscape and I'm wondering if you could give me advice as to the best place I can put these guys. I would like to espalier or trellis the quince.

A. The major limitation for all of these fruit trees is going to be winter cold temperatures for the citrus and summer high temperatures and reflected heat and light. In this part of the Mojave desert at a 2000 foot elevation most citrus trees, if not all of them, should be grown with care. This is not citrus country but if they are placed in the right microclimate they can be productive and healthy for many years to come.

East is a good exposure for quince because it tends to sunburn and get borers in full sun all day or hot locations. 
Pineapple quince with fruit in Las Vegas
Any of these fruit trees can be trellised or espaliered and suitable for side yards.
Apples and pears can handle full sun in open areas such as backyards if the soil is amended at planting and a four to six inch layer of surface mulch is applied to the soil beneath the canopy.

Apple trellised or espaliered in Las Vegas.
As far as citrus goes, you need a warm spot in the yard with little winter wind so they are protected from damaging winter cold and hope for the best. All of the citrus you like are tender to winter weather here but you will have the best luck with the most cold tolerant types of citrus such as kumquat, Myers lemon and grapefruit. 

Go to this website to learn about citrus varieties for the desert Southwest


White Fuzzies on Cactus Probably Cochineal Scale

Q. I planted a "cows tongue" or sometimes called "angel wing" cactus last spring and over the summer it began to develop some white cottony looking growth around each of the spines on the lower pads.  The white growth has continued and now covers much of the pads and some of the lower pads have actually fallen off. What is this white growth?  Is this a common problem with the cows tongue or is it common to all padded cacti and if so what can be done to rid the plant of the growth.  Someone had mentioned that it could be because of my watering schedule.  What do you think?
A. I don't have a picture of this problem on your cactus so I am following the KISS (Keep It Simple Stupid) diagnosis technique. The stupid part is to remind me that nine times out of 10 it is a common problem, not a rare event.

This is most likely problem is Cochineal scale, a common problems on cacti.
Heavy infestation of cochineal scale on Opuntia cactus.
If you touch it and it leaves a blood red liquid on your finger it is Cochineal scale. Both are scale insects hiding under that cottony growth and feeding on plant juices. When they reproduce and their populations increase, the feeding damage is so great it causes the plant or parts of the plant to collapse and ultimately die.
The red dye produced by cochineal scale when it is damaged. Notice how cochineal scale is commonly found close to the spines.
For either of these insects the control measures are the same. You can take a cotton swab and dab each of the cottony growths with alcohol or apply a systemic insecticide to the soil such as those containing imidicloprid so the poison will be taken up by the roots and moved to where this scale insect is feeding thus killing the insect.

The cochineal scale has an interesting history in Central America where this red extract was valued by Spanish colonizers as a dye until it was replaced by synthetic dyes. The actual insect was a very close relative of the Cochineal scale we see in our landscapes now. 

Tuesday, December 16, 2014

Remove Bottom Leaves in Cabbage to Reduce Pest Problems

Q. What can I use for bugs on my cabbage now?

A. The usual bugs on cabbage are aphids, whiteflies or cabbage looper. First off, remove the bottom leaves on the plants near the ground. They are nearly in full shade and no longer contribute much to the plant.
Cabbage leaves too close to the ground and cannot be sprayed on the underside. Most bugs will collect on the undersides of the leaves.
Once the lower leaves are removed it is easier to spray the bottom of the leaves, pointing the nozzle upwards.
These leaves are close to the ground, the underside is a great place for bugs to hide from predators and impossible to spray. In older plants they are tough so you will need to cut them off.
These insects also like to gather between leaves at the base. This is where you find cabbage looper eggs deposited. This is the white butterfly that likes to hang around cabbage and cabbage related vegetables, lay eggs that hatch into green worms that chew holes in the leaves.
A sure sign of insect problems are holes in the leaves. The plants should be sprayed at the first sign. Cabbage butterfly lays its eggs deep inside the crevices of the leaves. This area needs Bt or Spinosad sprays or dust.
You should have on hand at three to five of these organic sprays; insecticidal soap, Neem oil, Bt, pyrethrin and Spinosad and a good pump sprayer. Soap sprays will be used most often; twice a week. The others are applied less often, usually as needed.
Spray on top of the leaves as well as the undersides where most insects will hide and feed. Bt sprays like Dipel or Thuricide are used against pests whose adult forms are moths such as the cabbage looper. This spray or dust is applied between the leaves and left undisturbed for a few days so it can work.
Some insecticides say Bt right on the label while others may say Dipel, Thuricide or worm or caterpillar killer.

Whiteflies are controlled with insecticidal soap, pyrethrum or Spinosad sprayed alternately, a few days apart. Sprays need to be directed at the pests so it must be applied to tops and bottoms of leaves.
A popular brand of insecticidal soap


After harvest you will still have bugs in the cabbage and other leafy greens. A rinse in a clean sink with water containing 1 tablespoon of household bleach per gallon will kill any bugs remaining. Rinse all vegetables with clean water before preparing them.

Monday, December 15, 2014

Pyracantha Good Choice for Moderate Water Use Landscape




My only comments are that this can be fairly prone to borer problems if put into full, intense desert sunlight so that the sun damages its thin bark. There are definitely some varieties that birds like more (fruit) than others. Some varieties birds (Mockingbirds in particular) just won't touch. There are some varieties where the fruit can be made into pyracantha jelly. Google it. Other varieties have no flavor at all or sweetness and hence birds don't like them. Make sure you get pyracantha that have sweet berries if you want to fight with the birds over who gets them. Try them to see if they are sweet or not.

The colloquial name "firethorn" refers to the stinging sensation you can get when the thorns puncture your skin. It is not poisonous.

The fruit is closer to an apple anatomically (of course a very tiny apple) than a berry.

It can get aphids, spider mites, iron chlorosis and cotton cushion scale. It is in the rose family so it is not a desert plant and does best with wood surface mulches. It will get root rot if the soil is kept too went or the soil does not drain easily.

Creosote Bush, Mojave Native, for Desert Landscapes



Be very careful in watering these plants. They will die easily if they are watered too often or fertilized too much. They have a tendency to be a "nurse" plant for others in their shadow.
Creosote in the front and back. The difference? The ones in the front were along a desert road and were cut off by a road grader. The ones in the back were not and got woody. That's the secret if you want them small and bushy. Cut them to the ground when they are established and let them regrow.

Moringa Symposium in Manila Philippines Next November

International Symposium on Moringa

Manila, Philippines, 15-18 November 2015

Date of the symposium has been changed to 15-18 November 2015 (instead of 19-22 November 2015)!

For more information please go to http://www.ishs.org/symposium/488

Further details can be found in the brochure as well at http://avrdc.org/download/workshops/moringa%20brochure_REV7_FINAL.pdf

International Society for Horticultural Science PO Box 500 - 3001 Leuven 1 - Belgium
Phone: +32 16229427 Fax: +32 16229450

check out http://www.ishs.org/calendar for a comprehensive list of ISHS meetings

Harvesting the Sun - A Profile of World Horticulture by ISHS http://www.harvestingthesun.org

Get in touch:
If you'd like more information on a particular meeting, get in touch with the convener of the symposium.
For a specific query, to check out our FAQs or to contact ISHS go to www.ishs.org/contact

Why did I post this? I LOVE moringa (mulungay). It has a wonderful flavor for shrimp and meat dishes particularly cooked with coconut milk and hot peppers!

Sunday, December 7, 2014

Pruning Oleander Correctly Is Very Simple

Q. I purchased dwarf oleanders two years ago in five gallon containers. They are doing fine but are about four feet high. It is my understanding the plants can be pruned. I need to know the best time to do so and how far down to go without harming them.

A. Pruning oleander is very simple, much simpler than many other plants. You can prune them any time of the year without any problems. Having said that, they are usually pruned during the winter, late winter or very early spring.

Prune them with a loppers; the one that has two handles and you have to use both hands. Count the number of main stems coming from the base of the plant. Identify the two or three that are the oldest. They will be the largest in diameter.

 Remove these oldest ones within a couple of inches above the soil. You are done for this year! It takes about ten minutes and no mess to clean up! If there are some unusually long ones remove them from the base as well.

Repeat this about two or three years later. Continue this cycle of removing the largest diameter every three years or so.

Please do not use any hedge shears unless you don’t like the flowers. Having said all this, the absolute best time to do this in southern Nevada is February but you can do it any time without damaging the plant!

Euonymus Plants Have White Spots and Dying

Q.My euonymus plants are dying. These are all plants that have been in the ground 8-10 years. Now, they are getting a white spot on their leaves and shortly afterwards the plants die. The plants in my backyard did this last year, and now plants in the front have the same symptoms. Some people said they needed more water. That didn't do anything for the white spot. I tried cutting off the spotted leaves. That might help, but I am not sure. Is there anything I can spray or dust the plants with to stop the fungus?

Powdery mildew and leaf death. Powdery mildew is deeper inside the canopy were it is shady.
A. I am not sure what you mean by a white spot, whether this white spot can be rubbed off or whether it is permanent. These plants do get powdery mildew which looks like leaves have been dusted with white flour in some locations.This disease occurs on plants in shady locations.

If it is powdery mildew it usually means they are not getting enough sun or the canopy of the plant is not open enough for air movement. Powdery mildew, unlike other fungal diseases, requires very little humidity to become a problem. It is spread by splashing water from overhead irrigation hitting the leaves and splashing on others carrying the disease to these leaves and so it spreads.
You can buy a dust or spray to control powdery mildew but that just circumvents the problem and it will come back. The long term way to control it is to get more sun on the plants (move or prune them to open the canopy up), improve their health with fertilizers and appropriate watering. If the plant is under watered the canopy will be very open and I doubt you would have powdery mildew unless it is in shade or partial shade.
A white spot can also mean scorching of the leaves due to direct intense sunlight. This type of damage cannot be rubbed off with your fingers. It is permanent damage to the leaf. If this is the case then the plant may be in the wrong spot (intense sunlight or lots of reflected heat and/or light from windows and a west or southwest exposure and planted in rock.
 If this is the case then you need to move it away from this intense location into one that is more cooling with less intense sunlight. This is not a desert plant and cannot handle this kind of exposure. It does not like rock mulch very much so put it in organic mulch on the soil surface.
If it has only one drip emitter, put two or three depending on its size. If you are watering every day then water deeply every other day or every third day now. Make sure you fertilize this plant in the spring with a good tree shrub fertilizer.

If you want to move this plant, you can move it to a new location in October, moving as much of the soil with it as possible, and mulch it. Predig the hole and move it and plant it in less than 30 seconds once the roots are exposed.
Euonymus does much better with a wood surface mulch.Neem oil is a pretty good organic control for powdery mildew.

Why Does My Orange Tree Have No Fruit?

Q. I have a dwarf orange tree planted a little over a year ago. There have been no oranges on the tree. I have fertilized and I think I've been watering it correctly. The tree appears to be healthy just no fruit. Any suggestions?

A. Dwarf orange is not much help to me. The subject of oranges is huge. I need to know what type of orange it is, whether it has produced flowers or not and no fruit, or no flowers and no fruit. Varieties vary from early ripening - about 8 months from bloom - to late - up to 16 months from bloom.
There are three main groups: The normal fruited, without navels and with light orange colored flesh; the navel oranges, with a distinct navel development at the end; and blood oranges, with red flesh and juice.

There are about 73 varieties but US production focuses on Valencia, Washington Navel, Hamlin, Parson Brown, Pineapple and Temple. For home gardening there are many more than these six available from nurseries.

Remember, in southern Nevada growing citrus is marginal. Our winters or just too cold. That is the major limiting factor. The usual reason for not producing fruit are winter freezes.

Citrus should be planted in protected areas out of winter wind. They should be protected in the wintertime from cold. There is an excellent publication from Arizona on protecting citrus from cold weather.

Discouraging Root Growth Around Irrigation Pipes

Q. Having had several somewhat expensive repairs because of root damage to my sprinkler system, I am wonder if you have any suggestions for preventing/lessening such damage. I was told by one sprinkler technician that putting copper (he suggested pennies) in the ground would discourage root growth in the area. Is there any truth to this?

A. I am guessing the root damage was lifting the pipe out of the ground because roots were growing under the pipes. Roots will not grow into pipes unless there is existing damage to them, allowing for their entry but then there would be water everywhere. The other type of intrusive growth would be in drip irrigation emitters.

The best ways to avoid damage are to bury pipe deep, plant woody plants far enough from irrigation pipe so that it does not become a problem (preferably outside the irrigated zone of the plant) and use the appropriate type of irrigation pipe.

The best way to keep roots from lifting pipe and damaging them is to bury the pipe deep, as it should be. Irrigation laterals (pipe coming from irrigation valves directly to a sprinkler or other type of emitter) should be a minimum of twelve inches deep (0.3m).

Irrigation lines that are under constant pressure (pipes before the valves) should be a minimum of 18 inches deep (0.5m). All plastic pipe used for irrigation should be a minimum of Class 200 PVC when installed after or downstream of the valve. All pipe under constant pressure (before the valves) should be Schedule 40 PVC.

Class and Schedule refer to the internal pressures that these pipes can withstand which is related to the thickness of the walls of the pipe. All pipe installed should be "fresh" pipe, undamaged by the sun.
Class 200 PVC pipe on the left and Schedule 40 on the right
The PVC in most irrigation pipe is rapidly damaged by the sun if left exposed to it. You will see this damage by discoloration of the pipe. In extreme cases it will turn the PVC black from discoloration due to damage. Once this damage from the sun occurs, the pipe becomes very brittle and has no capacity for bending. It will shatter easily if bent.
Sun damage to white PVC irrigation pipe

Do not use, or do not let a professional use, PVC pipe which is discolored. Pipe exposed to the sun should be painted or wrapped. Paint will protect PVC from the sun's damaging ultraviolet radiation.
As far as pennies are concerned. This idea comes from the fact that copper is very toxic to plants.

Copper sprays are used to control some fungal diseases (Bordeaux sprays), copper is used to control mildew which are plants, copper is used to control algae and mosses which are plants, copper will kill plant roots when used as an appropriate pesticide (yes, it is considered a pesticide if it kills plant roots!) and copper nails will kill trees if pounded into the trunk a few inches apart.

The copper that kills is called elemental copper and must be available to react with plant roots. Perhaps plant roots in direct contact with pennies will be killed but plant roots just a few inches away probably will not. This would mean that if you were to protect the pipe you would have to line the pipe with pennies.

Just a side note. Whenever we pound anything into a tree we need to make sure the damage is minimal. Of course pounding anything into a tree damages it but some things are more damaging than others. Zinc galvanized nails will damage a tree more so than stainless steel. Whenever anything is put into a tree it is always best to make sure it is stainless steel if it has to be done at all. 

Oleanders In Containers Not Blooming

Q. I have two pink dwarf oleanders planted in 18 inch clay pots which are healthy looking but very few blossoms. One of my “expert” friends says simply that "oleanders don't like pots". Another "expert" says that I'm watering too much. Are either of these guys right or do you have any suggestions that might get some some blossoms?


Oleander flowers
A. We have dwarf oleanders at the Research Center in containers and they bloom just fine. The usual reasons for a lack of flowering are not enough light and pruning them incorrectly. Oleanders use a lot of water when it’s present.

There might be a couple of things you could try. Oleanders should be in full sun. They love the heat, and they love water and fertilizer to perform their best.

If the container is smaller you might have to water more often. 18 inch containers are not that large and don’t contain a lot of soil. If the soil volume is not large, the plant may not have enough water in the soil to last between irrigations.

Oleanders that are not getting enough water will look normal but have a very open canopy and not bloom well. Containers are not very forgiving when it comes to water. The water in that soil can be used up fairly quickly.

You can try using a soil moisture meter that you can buy from the nursery for about $7 and check the soil moisture before you water. Water when the meter is about half way between wet and dry, do not let the soil go totally dry.

Next, use a fertilizer like Miracle Gro or Peters and water it into the soil about once every six to eight weeks. Oleanders growing in the ground do not need to be fertilized as often.

Next, cover the soil in the container with mulch to help keep the soil moist. About three inches would be enough.

If oleanders are young or if they are pruned with a hedge shears they will not produce any flowers or very few. Don't prune it with a hedge shears if you want flowers, contrary to how you see it done around town. 

Will Eggplant Produce Through Fall and Winter?

Q. Will my eggplant plant continue to produce through the fall and winter?

Thai purple eggplant

A. They are warm season vegetables so they slow down considerably as temperatures drop.
Although eggplants will keep growing and flowering, they are more productive if cut back and allowed to regrow during late summer. Cut plants to about 6 to 8 inches in early August, cut at a crotch, fertilize and allow them to regrow.
Fertilize and keep soils moist to force them to regrow. The second crop will be ready to harvest in about six weeks after cutting them back. In Louisiana, eggplants are sometimes trellised and sheared late in the season for increased yield and quality.
The ideal temperatures for eggplant is 70 to 80 degrees F in the day and 65 to 70 F at night. Very few places, outside of a greenhouse, gives those types of temperatures consistently. Obviously, they do well in temperatures higher and lower than this. Fruit abortion can begin around 95 F even though the plant itself can handle heat.
Eggplant flower

As temperatures drop in the fall, eggplant still sets fruit but fruit set is not as reliable and fruit development is slower. Eggplant is generally more sensitive to cooler temperatures than its cousins, tomatoes and peppers.
Flowers consistently set fruit down to 60 F nighttime temperatures. Eggplants begin to get chilling injury at temperatures below 50 F.
Staking may be necessary if plants get big and full of fruit. Fruit touching the ground will spoil. Harvest fruit when they are one third full size and shiny. Over mature fruit will be spongy, the seeds begin to harden and the fruit surface becomes dull rather than shiny.

Snap fruit off of the plant but they will keep longer if they are cut from the spiny stem. Mulching helps fruit to set and improves fruit quality.

Sunday, November 30, 2014

Lawns Need Fertilizer Before It Gets Cold

Q. What does a lawn need In November or December?

A. You didn’t tell me what kind of lawn you have so I will assume it is tall fescue or an overseeded Bermudagrass. I like to recommend your final application of fertilizer for the year right around Thanksgiving. This last application of a high nitrogen fertilizer helps keep it dark green through the winter.
            This application must go on before it gets really cold. If you wait too long and apply it later in December you run the risk that your lawn will enter into dormancy and start turning brown. Once it turns brown, it is difficult to get it green again until temperatures begin to warm.

            Hopefully you have been applying a decent lawn fertilizer through the year. Good turfgrass fertilizers have half of their nitrogen content in the organic form or slow release. They also are relatively low in phosphorus compared to the other numbers. If you have been using good turfgrass fertilizers through the year, all you need to apply is straight nitrogen now such as ammonium sulfate or blood meal for organic growers.




            The usual rates recommended on the bag, in my opinion, are much too high. You can usually reduce that rate by 25% easily. If you are returning your lawn clippings to the lawn with a mulching mower you can reduce it to half of the recommended rate.
            You missed the ideal time to remove thatch with a dethatcher. That should’ve been done in mid-September to the first part of October. You can aerate your lawn or punch holes in it with an aerator any time of the year but mid-to-late spring is a great time for that.

Wait for Cold to Pass Before Pruning Grapes

Q. Should I cut my grapes back now or wait until spring?

A. I don’t like to finish pruning my grapes until about March 1. This is because I don’t know what kind of damage they will sustain this winter because of the cold and wind. If I prune them back to very short spurs or canes now, I run the risk of losing my crop or a majority of it.
            I usually prune grapes in two steps in our Las Vegas climate; the first step I remove most of this last year’s growth down to about 18 to 24 inches long. Then I wait for the majority of the winter to pass.
Leaving growth really long through the winter
            The second step occurs close to the first week of March. This is the time when I prune the remainder of last year’s growth down to about one or 2 inches long if I I am producing on spurs and about 12 to 15 inches long if I am producing on canes.
Spur cut back leaving only 1 to 2 inches
Do not cut your grapes back yet. Wait until the major cold weather has passed.

Assess Plant Cold Damage in the Spring and Fix It

Q. Are there are any plants I need to prune or trim down before the frost comes to the Las Vegas valley this year?  I noticed that oleander suffers greatly from frost, foxglove, asparagus ferns, potato vine and a purple flower trumpet flowered plant are kissed when the frost comes. Should these be covered also?

            Then we have the variability of the weather. It was not too long ago that we had unusually
Difference in cold damage between two different types of Oleander
warm winters where it hardly froze at all. Then we had a terribly brutal winter with the coldest temperatures hitting us in February when plants were just waking up from dormancy.
            Then we have variability in the plants themselves. As far as oleanders go, there are winter tender types and there are very cold tolerant types.
            My basic advice is to leave most ornamental plants alone. Wait until the coldest part of the winter has passed, or you begin to see the beginnings of new growth, and then remove what has been damaged. Oleander and asparagus fern can be pruned to within a few inches of the ground and they will recover.
Oleander will recover by summer if it is pruned to within a few inches of the ground. in late winter
            This doesn’t hold true with citrus. Citrus planted in cold locations will have to be protected if you want it to survive or you want fruit.

Green Bell Peppers Turn Colors When Mature

Q. Some of my California Wonder bell peppers are turning half black instead of red. Otherwise, they seem fine. It seems it happens the most when it cools down. Are the safe to eat?
 
Mini red bell peppers
Yum Yum Gold Peppers
A. There is a huge assortment in bell peppers. Years ago they all stayed green and when they ripened, they became partially red. People liked them. The market grew for red bell peppers.

Then breeders bred for the development of a solid, red color. Now we have beautiful red peppers that are held on the plant a little longer to get that red color to develop. The same was true of yellow, orange and even purple peppers.

But nearly all of the bell peppers start off green. Producers harvest them when they are large but immature so they stay green. If producers spend a little bit money for seed, get hybrids that turn a beautiful solid color and leave them on the plant long enough, they will get more money for them. And you get charged more at the store.

 We harvest peppers before they are mature if we want them green. However, if we get a cold snap this may cause them to develop their mature color sooner. In your case, I am guessing you have a pepper that turns dark purple when it is mature.

The clue was it was half black instead of red. Your pepper is just fine to eat and it actually might be a little sweeter because of the cool weather. By the way, that purple color is probably anthocyanin, a rich antioxidant.

How to Correct Brown Spots on Indian Hawthorne Leaves

Q. Two of my Indian hawthorn bushes developed unhealthy looking brown spots on their leaves. It started on the southernmost of the two bushes and then the second was affected. These are in the middle of a row of bushes planted along the sidewalk when the house was built in 1986. None of the bushes get a great deal of direct sunlight, but bushes on both ends of the row, with conditions about the same as for these, are looking all right. Can you tell me what is wrong with these two bushes and how to fix it?
 
Indian Hawthorne with leaf browning
A. From the picture this looks like a soil related issue. The soil around the plant looks like it is fairly rocky and I am guessing unimproved over the years. 

I think you'll see a big response by taking a bag of decent compost and spreading it under the plants one or 2 inches thick and watering and in. The other thing you might try is replacing any rock mulch under the plants with wood chips that will slowly decompose and improve the soil. 

If you put the compost down now and water it in, you should see some improvement in the plant when it continues growing in the spring. The second thing you could try doing is spraying the foliage with liquid good quality fertilizer. 

Miracle Gro or Peters would be a good choice. Use one or 2 teaspoons of liquid detergent in a gallon of fertilizer spray to help it penetrate the leaf surfaces. I would try spraying the foliage during the winter. If it's in a warm spot, you may see a response before next spring. Otherwise you'll have to wait until growth resumes early next year.

Monday, November 24, 2014

Download My Notes and Presentation on Salinity

You can download my two presentations, and the presentation notes, on salts and salinity problems in landscapes that I presented at the Desert Green Conference in November. The Presentation Notes should be downloaded to read along with the presentation.

Click on the link below. Viragrow sponsored my presentations at the conference and they are posted on their website, not here. As with all of my presentations, they are copyright protected but are free for use by individuals, any nonprofit organization or corporate trainers.

These are PDF files. The presentations are quite large so it will take some time to download if you have a slow connection. I have tested all of them and they all download. They are on the website. Just scroll down to find them.

Go on this link to download my presentations and notes.



Sunday, November 23, 2014

Do You Have Bottle Tree Problems? Contact This Guy.

These trees are native to Australia. We have been planting Australian bottle trees here in the Las Vegas Valley since the 1980's. Doug offered to help with your bottle tree questions. 

Att: Bob Morris…That was a great answer to the Bottle Tree query about watering.

I grow Bottle trees……I am happy to assist with any queries you may have with Bottle Trees.


Regards, Doug Sowerbutts.

Bottle Tree Plantations
PH: 0412 222 535

You Can Download My Presentation on Fruit Tree Pruning

This past week I made a 20 minute presentation to the Southern Nevada Arborists Group (SNAG) on establishing the architecture on fruit trees. You can download my presentation as a PDF file as well as notes for the presentation. They are quite large so it may take some time to download if you have a slow connection. I was supported my presentation by Viragrow so it is posted on their website. I tested the link and it works.

Click here, go to the website and download my presentation and notes

How to Clean Drip Emitters That Are Plugged

Q. How do I unplug drip emitters that are plugged?

A. Drip emitters can get plugged from salt accumulation and debris. Never cut irrigation lines that have drip emitters on it with a hacksaw blade. The plastic debris created by the hacksaw blade is nearly impossible to keep out of the irrigation lines. I will guarantee you that this debris will end up
Salt accumulation on drip emitters.
in your drip emitters and plug them. Cut PVC irrigation lines with a PVC cutter. It leaves no debris to plugged emitters. You can cut polyethylene pipe, the kind used for drip emitters, with a pruning shears.
PVC cutter
Make sure the ends of the drip lines can be cleaned by opening them up and letting water flow for 15 or 20 seconds about once a month. You can buy little figure 8 devices to go on the end of the irrigation lines or you can bend them over and slip on a small piece of PVC pipe to hold that shut.
Figure 8 for closing the end of a drip irrigation line

Secondly, put drip emitters facing up, not down. If salt accumulation is the problem and the emitters can be removed without damaging the drip system, remove and soak them in vinegar for a couple of hours.
Button drip emitter
If you cannot open the drip emitters to clean them, try poking a needle or pin through the opening to see if you can unplug them. In the past I have knelt down on the ground and lifted the emitter to my mouth, after I washed the outside, and sucked on the emitter to try to get debris cleaned from the opening.
If you cannot remove the emitters from the drip line, you might have to replace them. Make sure when you buy drip emitters they are the kinds that you can open and clean easily. Flag drip emitters are inexpensive and can be cleaned easily. Button emitters can be more difficult.
Flag emitters are easy to clean
Drip tubing with built-in, in-line emitters can be the most difficult. If you buy the built-in emitters, by a name brand such as Netafim, Toro, etc. make sure you have a filter on your drip system somewhere after the valve.

If you work on drip systems and have to cut the tubing, after you repair it, flush the system with water by opening the ends and letting it run out the ends. If you don't do this, debris will get pushed into the emitters and can become a problem. 

Planting Potted Fruit Trees in the Landscape

Q. We are ripping out an old, dead lemon tree and would love to plant my potted dwarf citrus trees in its place about a foot from the garage. I have a dwarf lime, Meyer lemon and a Page mandarin. They would be getting slightly less sunlight, but still would get sun for most of the day. They have all been in pots for about 4-5 months. Do you anticipate any problems with this idea?

A. Four to five months in a pot is not a problem. The roots are still exploring the soil in the container and have not been in long enough to cause a problem. In a warm location protected from the wind they should be fine.
These are small trees but put your drip emitters a foot to 18 inches from the trunk away from the garage to encourage root growth away from the foundation. This will keep the soil close to the garage drier and less likely to cause salt damage.
It would be better and more attractive if the plants were trained against a trellis or espaliered. You will need to keep the branches pruned off of the tree that are growing toward the garage.
Espalier citrus after planting
Some people will have a problem with it being planted that close to the garage. It is not going to be a problem for the garage. The roots will not be a problem for the foundation. We see citrus espaliered near a wall or foundation a lot. 
Remember that citrus is borderline in the Las Vegas Valley at the middle elevations. It just gets cold here and they may or may not work depending on the location. Pick a warm microclimate in your landscape that doesn't get a lot of wind. Cold winter nights below freezing I would throw a blanket over them.


Grubs Feeding on Lantana

Q. This season our Lantana has done poorly. For each plant we dig up there appears a bunch of grubs. What's going on?

A. I was alerted to this problem by a reader. The Lantanas were not doing well. That is surprising because they grow like weeds in the Mojave desert with a little bit of soil improvement, fertilizer and water. 

When they dug this Lantana to replace it, they found these grubs in the hole. Grubs like to feed on soft, succulent plant roots. They are general feeders so they will munch on many different plant roots. Fortunately they are pretty easy to control with traditional pesticides as a liquid a soil drench and organic pesticides. 

The organic pesticides that seem to work on a natural oil-based products such as thyme oil, Rosemary oil and others. They can also be controlled with insecticides made from bacteria or beneficial nematodes. They come in a variety of trade names but look for them in your organic section of the pesticides.

Grubs that were feeding on the roots of a Lantana. Taken by the reader.

Preparing Planting Holes for Italian Cypress

Q. Two of my Italian Cypress trees died so I am replacing them. What size do you suggest I buy and how to I prepare the area prior to planting and correct way to plant them?

A. Get the smallest plants you can find if that size is acceptable to you. I would start with five gallon plants if it were me. They will catch up to larger plants in a very short time.

Amend the soil with about 50% compost to a depth equal to the depth of the container. The whole should be dug a distance 3 to 5 times the diameter of the planting container. It is more important to dig the hole wide than it is deep. If the soil is particularly hard to dig beneath the container then I would take a posthole digger and dig a chimney at the bottom of the container and fill that hole with amended soil to improve drainage.

Thoroughly soak this area several times after you planted the trees. Five gallon plants should not need to be staked. With improved drainage they should be able to handle more frequent irrigations without problems if that is necessary.

Fertilize them once in January or February with an all-purpose tree and shrub fertilizer.

Put them on a valve with other trees and shrubs. They will do fine on the same valve with most of your landscape trees and large shrubs as well as fruit trees.

What Killed My Gopher Plant?

Q. What do think the problem would be with my three gopher plants? They seem to be getting enough water.
Gopher plant collapsing during warm weather
A. This plant is a Mediterranean plant which means it likes soils that drains easily, hot summers within infrequent irrigations and cool rainy winters. Normally this plant is very prolific and grows well in our desert soils. In fact you may see it pop up here and there once it's been planted.

Whenever I see branch die back on plants like this it usually indicates there is too much water remaining in the soil between irrigations. This means it is either watered too often or the soil does not drain very well or both. If this is the case, you will not solve this problem by simply giving it less water. You either have to take up the plant, amend that soil and replant it or move it to a new location that has improved soils and can handle frequent waterings.

If you cannot change how often the water comes on, you will have to change how rapidly the soil can drain the water. You will not change the soil by adding sand. This will make it worse. You have to use amendments such as compost and perlite.

Once you have solved this problem you could cut this plant back to three or 4 inches in height and have it regrow again. Dead portions of the plant you can remove completely. Fertilize lightly in the early spring.

Do's and Don'ts to Protect Plants From Freezing

Q. Are there any do’s and don’ts you can give regarding covering plants to protect them from the winter weather here in Las Vegas. I have some small citrus that are in the ground. 

A. This past week we had freezing damage up in the Northwest part of the Valley. Probably the single best publication on this topic comes out of Arizona and you can download it below. I have never thought much about using Christmas tree lights around trees or shrubs unless you can capture that heat. And those little LED lights don't put out much heat. In my opinion, the most sustainable way is to find landscape microclimates and cover plants with a blanket of some sort. 

Stay away from open areas that get windy and narrow passageways between homes. These narrow spots tend increase wind speed. The two damaging factors are low temperature and wind. Focus on these two factors to protect your plants.I worry a little bit right now with this unexpected cold weather about early snowfall. There are still a lot of leaves on the trees and if we get some snow, will see plenty of damage.

Streets that run North and South in the Valley tend to get colder than streets running East and West.I like to call these urban canyons.

Protect from cold damage click here

Cold damage to Sago Palm
Cold damage to bottlebrush
Cold damage to star Jasmine
Cold damage to Mesquite
Cold damage to agave