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Saturday, January 2, 2016

Pruning Miniature Peach Is a Little Different. I can help.

Q. Do you know of any person, to be paid, who will come to my home and prune two dwarf peach trees? I am 84 (widow) and really don't know how to prune these trees. I have tried for 5 years now and  know what I  do  is wrong; I need help. I have asked our landscapers (live in a condominium association) and they don't have any one in mind.

Please, do you have any suggestions as to where and how I might obtain help?

Miniature peach requiring pruning
A. I can help you with that but you must agree to learn how to do it. I do not do it as a landscaper or a service company but I will help you learn how to do it for yourself. 

If these are miniature peaches, they do require a different way of pruning than peaches that are kept small through pruning. First, we make sure branches on the lower part of the trunk will not touch the ground when they are loaded with fruit. We will focus on thinning out some of the branches so that there is better light penetration inside the canopy. Lastly, we will thin out the new growth so that there is fewer of them. You will be required to thin the fruit in March so that the remaining fruit becomes larger and higher-quality. If you need me to show you how, I can do that as well when that time comes.

Pruning of peach should be done before February 1 in our climate. If you are interested, I'll be happy to show you how. It will be within your budget. You should have an appropriate pruning shears and a small loppers. I will bring mine but you should have your own. If you don't have tools or the appropriate ones, let me know and I will bring good ones for you that are reasonably priced and you can reimburse me.

When to Prune/Protect Myers Lemon Depends On…

Q.When is the best time to prune a Meyer lemon tree that is planted outside and should they be covered when the temperature goes below freezing?

A. First of all, citrus does not require a lot of pruning unlike some other fruit trees. You would focus on removing crossed branches, broken branches or branches too close together. Generally speaking, prune citrus right after you harvest the fruit. Myers lemon may begin flowering in January or February and that becomes a bit late because the fruit will not finish until December of the same year, 10 months later.

Flowers of Myers lemon
This is why it is important to remove the fruit on Myers lemon by the end of December or it may interfere with flowering the following January or February. Growing citrus in our climate is always risky because of winter freezing temperatures. With most cold sensitive plants we would want to wait until after the last possible freezing event. This would put it into perhaps mid-February.
Immature fruit of Myers lemon in container
Waiting this long, even though it's the right thing to do with winter tender plants, is a problem with Myers lemon because it begins to flower so early. So we have to take our chances and prune right after harvesting in early January before flowering begins.
This table taken from University of California Riverside document below

Myers lemon should handle temperatures down to about 20° F. The amount of damage depends on the temperature but also on the length of time the temperature remains. So 20° F just before sunrise is a lot less damaging than reaching 20° F at 3 AM and staying there until sunrise. 
Immature fruit of Myers lemon in container

The number one reason we have fruit failure in Myers lemon in our Las Vegas climate is because of late freezing weather. Even though Myers lemon can withstand temperatures close to 20° F, the flowers or young fruit cannot. They begin to bloom in January or February and may have flowers or very small fruit on the tree and a light freeze comes by and ruins the crop. Then I get emails about why my lemon tree didn't produce any fruit this past year or last two years. 

It is extremely important to put citrus in warm microclimates in Las Vegas yards and out of the wind in our winter cold climate. You will need to cover Myers lemon whenever temperatures get close to freezing, 32° F, if they have flowers or small fruit. If they do not have flowers or small fruit than they can withstand colder temperatures.

Another point worth mentioning is that cold hardiness varies during the winter depending upon the weather. During a normal winter, temperatures slowly but continually drop colder and colder until we hit our winter minimum temperatures. Temperatures stay cold during the deepest part of the winter and then minimum temperatures begin to climb as we approach spring.This past fall was nearly perfect as temperatures, generally speaking, dropped lower and lower at a very slow pace. This gradual drop in temperature was reflected in our nice fall colors which remained for about a month in November and December.
We had some nice fall color like this during November and December In Las Vegas due to the gradual drop and fall/winter temperatures
Some fall/winter/spring weather is not this nice. Sometimes we can get a sudden drop in temperatures in the fall that can catch normally cold hardy plants off guard. Then we see damage to these plants at temperatures warmer than their minimum temperature.

The reverse can happen in the spring when we have very low temperatures, followed by an unexpected early rise in minimum temperatures then followed by a sudden drop to freezing weather. This sudden drop below freezing after a warming spell can damage trees at temperatures above their minimum.

Sorry for the long winded answer but cover Myers lemon that has flowers and fruit as soon as you hear temperatures might reach freezing.

Friday, January 1, 2016

Lemon Disappearance Due to Rats

Q. We have a critter attacking our lemons. It does not eat the fruit, only the peel. It eats the peel so cleanly that only the bare fruit is left hanging on the tree. The white pith is gone to. It is a strange thing to see a naked lemon hanging on the tree. Do you have any idea what this critter could be?
Pomegranate hollowed out by rats
A. This is most likely rats. I have not seen nor has it been reported to me directly but several reports in the US and Australia attribute the eating of lemon peels but not the pulp to rats. This can happen to fruit on the tree or on the ground.
            Rats will also gnaw on the bark and branches of citrus trees.
Contrary to this, it has been reported that rats will eat the pulp of oranges and pomegranates but not the rind or outer covering. It is not understood why but lemon peels and pomegranate juice is high in Vitamin C and calcium.

Rats produce their own Vitamin C inside their bodies so it is not clear what they are going after by selectively eating rind and not the fruit. It is also reported to me that rats will eat guava fruit and papaya in the tropics, another source of high Vitamin C.

Research on rats and Vitamin C in the early 1900's report that rats may benefit from extra Vitamin C in their diets in growth and reproduction. Better get the rat traps out. 

Winter Watering Schedule for Lemon

Q. I have a Eureka lemon tree and a Rio Red grapefruit tree. Is it best to stop watering them through the winter weather or should I continue with their regular watering schedule?
Eureka lemon growing in Las Vegas Nevada while fruit still immature

A. They should have a winter watering schedule and water to them should not be turned off. Get a general idea when to water by monitoring the soil moisture with an inexpensive soil moisture meter. Purchase these at most nurseries or garden centers where they cost less than $10.
Simple moisture meter use to get a general idea of the water content of the soil

A winter watering schedule should be somewhere between 10 days and two or three weeks. Plants in containers must be watered much more often.

Push the tip of the meter as deep as you can in the soil somewhere beneath the canopy of the tree and midway between drip emitters if they are present. Do it in two or three locations. These meters are inaccurate but they give you a general idea if the soil is dry or wet. Water when they meter is midway between wet and dry.
            Trees that have leaves present use more water than trees without leaves. A layer of wood chips as a surface mulch will cause you to water less often. A lack of water or very cold weather may cause leaf drop

Apple Tree Not Dropping Leaves

Q. My apple tree is still full of leaves and hasn’t lost one yet. Should we wait to prune once it starts losing leaves or is it okay to prune in the next couple of weeks? The leaves have turned a purply brownish color but are still very much alive.

A. Go ahead and prune. We have not had a freeze hard enough to knock off the leaves. The tree is fully asleep for the winter.

Actually you can start pruning fruit trees as soon as they stop growing in late fall. We normally wait until leaf drop because we can’t see where to make the pruning cuts easily. You can also wait to prune until near February and that will be fine as well.

Leaves can be removed by running your hands down the branches if they are in reach. Try shaking the limbs or rap them lightly with a broom and they should drop as well.
If you want the leaves to drop on their own, turn off the water to the tree until leaves begin dropping and then resume your irrigations as needed.

As for me, I would just wait for normal leaf drop if it is difficult to see where to prune.

Walnut Husk Rotting with Worms

Q. Our walnut tree is at least 10 years old and producing wonderfully for the past 3 years. This year toward the end of the season, the husks started getting black. I opened one and saw little white worms. I opened the nut shell and saw no damage to the nut itself, so we did nothing. By the end of the season, most of the husks were on the ground, all black. Of the husks with nuts, the nuts were okay but there were a lot of husks with dried up black nuts. We also noticed this larger branch on the tree that seems to have split its bark.
Damage to husk of English walnut
Damage to English a walnut limb
A. This sounds like walnut husk fly damage to the husk. If walnut husk fly damage starts early enough to the husk they can cause a nut failure just like you describe. If damage to the husk is later in the summer, the nuts inside will fully develop.

Walnut husk fly adult is around the size of a housefly and lays eggs just below the surface of the husk. This blackens the outside of the green, immature husk and causes it to get soft. Eggs from walnut husk fly hatch into maggots, or worms as you call them, feeding on the inside of the husk.
After a few weeks, older maggots fall from the husk to the ground and burrow into the soil where they spend the rest of their life before emerging as adults the following summer. They emerge as very colorful, mature flies ready to repeat the cycle. This lifecycle is repeated once a year with egg laying on husk starting in mid to late summer.

            The University of California has an excellent fact sheet on the Internet concerning the walnut husk fly and located at http://www.ipm.ucdavis.edu/PMG/r881301211.html. Control measures are mentioned but a bit difficult. If there are other walnut trees in the area this could cause an increase in the population of this pest in coming years if they are left uncontrolled.

Damage to tree limb

The pictures of the tree limb you sent look like borer damage to me. The same borers that attack fruit trees such as peach also attack walnut. Pull off the loose bark from the limb and look for damage from borers on the surface of the exposed wood.

If borers damage is present, remove all of the loose bark with a sharp knife. If the damage to the limb is more than halfway around its circumference, remove the limb. If it is less than half, the tree has a good chance of recovery if all the loose bark is removed down to healthy wood.

Covering a Joshua Tree During Freezes?

Q. I transplanted a Joshua tree into our new backyard in March. It is doing great. Do I need to cover it as temperatures dip down below freezing? 

A. No, you do not need to protect it with any kind of freeze protection through the winter. They are good down to about 10F. Make sure you are watering it infrequently or it can develop root rot and die. Fertilize it once lightly in the early spring with a fruit tree or rose fertilizer.

Just a quick note on covering plants. If you are using a plant cover that does not allow much light through it, you should be taking it off during the day and replacing it whenever you think temperatures are getting too low. If you are using a frost blanket or frost protection which allows light through it, you will not need to take it off during the day. However, you should remove it as soon as danger of those freezing temperatures have passed.

Desert Horticulture Meetup Group Has Been Organized for Jan 23

I started a new Meetup Group on desert horticulture. The first meeting will be on January 23. The focus is on successful horticulture for fun, pleasure and profit in the desert. Get in on the ground floor because the direction of this group will depend on the members.

Find out more about the Desert Horticulture Meetup Group

In the first meetup we will have introductions and I will give a brief presentation about our desert environment and the problems this environment presents to us in horticulture. At the conclusion we will discuss our future plans as a Desert Horticulture meetup group.

Who: Anyone
What: Growing plants in the desert for fun, pleasure or profit
When: 9 AM, Saturday, January 23, 2016
Where: Viragrow meeting room, 1100 East Delhi St, North Las Vegas, Nevada

Tuesday, December 29, 2015

Brown Spines on Agave stricta

Q. A quick question about a newly planted Agave stricta. Within 2 weeks of planting the spines have begun turning brown from the tips down. Do these plants generally brown out in the cold or is this one dying? It is a 15 gal plant - purchased from a local cactus nursery. It had some brown on a few stems shen purchased, but not like this. It was planted according to the instructions from the nursery with a sand/soil mix at bottom and sand around the perimeter.
A. I had to look up that particular agave because I did not know it. There is some information about it at the San Marcos nursery website

It is found growing in southeastern Mexico in its native habitat at about 5000 feet from what I could find. San Marcos nursery says it will handle temperatures down to at least 20° F. This is for Agave stricta ‘Nana’ so I am wondering if this is what you have or not.

A. stricta is confused with A. striata a lot because they look almost identical. This particular cactus may benefit if it's not placed in a location where it receives very hot direct sunlight in the afternoon. It sounds like it is a little bit delicate perhaps because of where it grows and its elevation.

Click here to see what Agave striata looks like

I am thinking you may have one of two or three things going on with yours. I don't think it's temperature. If this cactus was growing in a shaded or semi shaded area and then placed into an area that receives a lot of direct sunlight in the late afternoon it's possible that it could be sun damage.

How you planted this cactus sounds fine but if you are watering it too often, even with good drainage, this could also cause problems. When water is scarce it relies on internal storage of water. During the summer I would not water it more than every three weeks if you are planning to push some growth.

If you're happy with that size, you can water it less often than that. It is also possible that the soil mix that was used could have been a little too saline. Flush the soil with several gallons of water a few times to remove any excess salts if you think this might be a problem.

But I do not think it is a temperature damage but more likely to be sun damage or damage from irrigation. During the winter you should be able to water only once or twice during the entire winter.

Further thinking, it is POSSIBLE it could be a salinity problem. There are soil mixes out there that use sands with lots of salts in them and they are not washed sands. Wash plenty of water through the soil where you planted a couple of times a few weeks apart to reduce salt problems. Now is a good time to do that because temperatures are cold and tolerance to lots of water in the soil is much higher in plants during cool or colder weather.

Acacia longifolia Tolerance to Cold in the Mojave Desert

Q. Would Acacia longifolia do okay in the Las Vegas area?

A. San Marcos Growers reports cold hardiness down to 20F so it will take temperatures similar to Myers lemon, a fairly cold hardy citrus.

It is possible it might have dieback during some extremely cold winters but it should re-sprout easily from its base once it has established for one season. Like any Acacia I worry a little bit about allergies from its pollen. It is a rather large plant usually grown as a shrub but I think you could train it into a small tree fairly easily. It should handle our soils with little problems just make sure that you amend the soil at the time of planting with compost.

Anyone with experience with this plant?