What To Do to Fruit Trees in December and January

Todo Lists for December and January

Pruning: lower the heights of fruit trees. Lower the heights of fruit trees if you want to do most of your tree management without a ladder. Lowering the height of your fruit tree to a pruned height of 6 1/2 feet will allow you to prune, spray and harvest while standing on the ground. Most full sized fruit trees can be kept to this height through judicious pruning methods. Apples should be grown on a semi-dwarfing rootstock.

Pruning: begin pruning for production. Each type of fruit tree is pruned differently. You must know where your fruit is being produced on the tree that you are pruning. Delay pruning grapes until late February.

Mulch. Use organic mulch in the Orchard or around fruit trees. This is not the same as bark mulch which is inferior to wood mulch. Wood mulch can be kept to a depth of 4 to 8 inches around fruit trees. On younger trees, keep wood mulch 12 inches away from the trunks until they are 6 to 8 years old. Green waste from pruned and chipped ornamental trees makes an excellent mulch. Avoid using trees such as Mesquite with their large thorns and palm trees which decompose very slowly. Organic mulches such as wood mulch return nutrients to the soil, increase microbial activity, retain moisture around the plant roots, reduce weed problems and help keep the soil cool.

Four year old trees with wood mulch. Keep the mulch
six inches from the trunk on young trees.

 Irrigate fruit trees deeply every 10 days. After leaf drop, irrigations can be applied every 10 days to two weeks if you have a surface mulch applied to the soil. Sandy soils may require irrigations weekly to every 10 days. Heavier soils may require an irrigation every two weeks.

Borer control. This time of year concentrate on removing borer damage from fruit trees. Look for borer damage on the upper surfaces of limbs, particularly of peach, nectarine and an apricot. Using a sharp, sterilized knife remove the damaged wood from these areas. Be sure to cut all the way down to fresh wood when removing damaged wood. Let the tree heal by itself. Do not apply pruning paint but you could apply whitewash.

That is one of the flatheaded borers.

Dormant oil application. Dormant oil is an insecticide made from petroleum products used in organic production. The oil itself is not toxic but spraying it on the limbs and trunk of fruit trees helps to suffocate overwintering, usually soft bodied, insects that are pests of tree fruits. Usually to applications are made during the winter months.

Weed control. Weeds that are living close to your fruit trees provide homes for overwintering insects. Once your trees begin growing in the spring, these insects move from weeds to your trees. Keep in areas near your fruit trees without weeds.

Using a backpack sprayer to apply whitewash. Clean
thoroughly when done!

Renew whitewash on fruit trees if needed. Whitewash provides a light colored covering to the outside of the bark of the tree and its limbs. It is particularly important in reducing sun damage to fruit trees due to our high light intensities. Whitewash can be made by diluting white latex paint with an equal amount of water or more. Dilute the white latex paint so that it will color exposed areas of the tree white and reduce sunburn. Reducing the sunburn will reduce the damage from borers.

Pull wood mulch away from the trunks of young trees about a foot. Wood mulch that gathers around the trunks of small trees can damage them.

Remove any stakes from trees planted early in the year. Fruit trees that are planted correctly and are not overgrown in their containers will need staking for only one season. If your trees have not become established after one season, there is a problem.

Limb spreaders easily seen in the winter time

Remove limb spreaders that were used earlier in the year. Limbs spreaders are used to increase a limbs angle of attachment to the trunk of the tree. Ideally, this should be a 45° angle. Limbs spreaders can be applied to the tree now but there is less danger of breakage in larger limbs when the sap is flowing in March. Ideally they should be applied when the limbs are one to two years old.

 Fertilize fruit trees. Fruit trees respond nicely to fertilizers with moderate amounts of nitrogen, high phosphorus and moderate to high potassium. Do not apply them earlier than January. Mineral fertilizers can be granular or in the form of stakes. Organic fertilizers are preferred but can be slower acting. Apply fertilizers where water is delivered to the fruit tree. Keep all fertilizers 12 inches away from the trunk to prevent damage to the tree. An iron chelate, preferably with the chelate in the form of EDDHA, should be applied to the same area, watered in and covered with mulch.

Irrigation system should be checked for plugging, broken lines and runoff.

My Shrubs Growing In Rock Mulch Turned Brown in November

Q. I now water once a week but my shrubs are looking like they might in the hottest part of the summer. Leaves look dry, burnt and falling off. My average shrub is about 3'x3' and receives 3-4 gallons per week week based on my emitters and time on. Did I cut back to much ? What should I do to try to revive them ?

A. Your watering sounds very appropriate and probably what I would have scheduled as well. You have to make sure, however, that the water which is scheduled to be delivered to your plants is actually getting there. Make sure you check for plugged emitters when the system is on. You should have a filter on your drip system even if you are on city water.

             It could be several possibilities. I have to walk through them with you because I don't know much about their previous history. For me, it looks like possibly watering, possibly collar rot at the base of the trunk where the rock mulch sits against the stem, it could be very low temperature damage as possibilities. If there were some very low temperatures just prior to that than this could be just that. If there were no low temperatures than most likely it is not. Then we have to look at watering issues including the rock against the trunk.

First determine whether the plant is dead or not. Bend some branches and see if they snap. If they are still supple and just have damaged leaves then it is a temporary setback and they will regrow and set new leaves in the spring. If they snap when you bend them, it may be dead. You will have to pull it anyway so start bending the branches and see how much of the plant is dead. If the amount is sizable, remove it. When you remove it look at the trunk where the rock mulch was resting against it.

Use a knife or your thumbnail and scrape the bark away from the trunk starting about an inch above where the rock mulch sat and down along the stem to the roots. Look to see if there appears to be a dark area or rotten area in the trunk or bark around the rock mulch line. If there is, then it is collar rot. Make sure on any new shrubs that rock mulch does not lay against the trunk or, in some cases, the plant was not planted too deeply. It should have been planted the same depth as it was growing in the nursery container. Nurseries don't have many plants this time of year because they are trying to reduce their inventories. You can look for a replacement plant but chances are you may not find one that you like until next spring when it gets warm. I hope this helps.

Hobby Greenhouses a Special Challenge in the Hot Desert

Q. My helpful husband gave me a 6 x 6 foot greenhouse for Christmas and I'm wondering what in the world I can do with it here in Las Vegas. I am thinking that I can get a head start on growing seedlings and things like that, but during the summer months, it will probably be a storage area since it's so hot here.  I have it located on concrete on the southwest side of my house, and unfortunately there is no other place for it. Also, maybe I can extend the season into winter months? Any information would be great.

A. That was very thoughtful of your husband. As you have probably already figured out, greenhouses can be tough to manage in our climate. But it can be done. You have one thing going for you. You have a greenhouse. What you don't have going for you is that size and its location.

            Small greenhouses are difficult to manage in this climate because they heat up so rapidly. By modifying your greenhouse you may only have to shut it down for two or three months during the summer.

Generally speaking in hot climates with lots of sunshine, tall greenhouses are better than short greenhouses. Anything you can do to make the greenhouse taller is a good thing. The heat accumulates toward the top of the greenhouse. As the heat builds it puts heat on the crops growing lower. The taller the greenhouse, the easier it is to keep the heat off of the plants.

That Southwest exposure is also tough in the summer but would be nice in the winter.

            During the summer the sun is nearly overhead and in the winter it is at a low enough angle that it mostly comes in through the side walls. You might want to consider orienting your greenhouse so that the door is on the East or North side.

            Next, I would put some shade cloth on the roof or paint the roof with white latex paint to reduce your solar load. There is some bamboo fencing that is quite reasonable that you might consider placing over the roof to create some shade during the summer months.

            These are all options. I would probably look at the bamboo fencing first since you can kind of adjust it by putting more or less of it on the roof. These should be done on the outside of the roof, not the inside.

            If it's possible, you might consider putting a couple of vents in the roof that you can open or that will automatically open for you if there is too much heat in the greenhouse. This will allow some of the heat that accumulates at the top of the house to exit and will help reduce the heat load somewhat. It will not cure the problem but it will reduce the problem.

            You might also consider a small swamp cooler that draws air from the outside. Put it on the cooler north or east side if possible. It is also important that the greenhouse is not sitting in a rock landscape.

            If it is surrounded by rock, it will compound your problem. About the most you will be able to drop the temperature from that little swamp cooler is going to be about a 20° difference from the outside air temperature.

            Another way to drop the temperature is to replace one wall, or build into the wall, a pad system similar to commercial greenhouses. This uses recirculating water just like a swamp cooler but the pad is built right into one of the side walls.

            On the opposing wall is a fan that pulls air through the wet pad cooling the inside of the house. If the pad is 4 to 6 inches thick, it could cool the house significantly provided you reduce sunlight entering through the roof.

Getting Christmas Cactus to Bloom Requires Only Natural Light

Q. How do I get my Christmas cactus to bloom? I was given a 9" pot back in November, kept it indoors with plenty of light, only to find out that it's supposed to be in the dark for 14 hours a day. I started that 3 weeks ago, been watering once a week, gave it cacti food twice, but no blooms.

A. The Christmas cactus is a true cactus and nearly identical to the Thanksgiving cactus. These cacti have slightly different bloom times so they get the names Christmas and Thanksgiving cactus because of their bloom times.

            The amount of light (actually it's amount of darkness) will typically get them to bloom if all the light they receive is natural daylight. It's when they receive extra light inside the home that it can break this rhythm of flowering and cause them not to flower at this time of year.

            These cacti bloom when the nighttime darkness approaches what we get a minimum of 12 hours of darkness. So if they are growing inside they need to be covered so they receive no light from artificial sources. Once covered they will bloom if they remain covered, religiously, for six weeks . They also respond to cool temperatures. So placing them in a colder location in the dark also will help them to bloom.

            Christmas cactus is what we call an epiphytic cactus which means it does not grow in the soil in the wild but on the surface of other plants such as trees. We can however put them in containers and grow them in containers with soils amended with lots of truce one compost, similar to what they would find growing on the surface of a limb in the tropics. This is much like orchids and bromeliads. These cacti can be grown outside here on the northern or eastern exposure in a well amended soil or in containers but you must bring them in if there is any chance of freezing temperatures.