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Thursday, December 22, 2011

Plant Winter Vegetables Now, Its Not Too Late

Plant lettuce, peas, cabbage (transplants), cauliflower (transplants), carrots, radishes and spinach. These vegetables can germinate and handle lower soil temperatures in the warmer parts of the garden (45F soil temperatures for germination). Prepare the soil by loosening it and applying a starter fertilizer high in phosphorus. Cover the seeds with a dark topdressing to help warm the soil. Activated carbon works great for transferring heat to the soil.

Orchard Calendar: December

Lowering the height of fruit trees
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.

4 to 8 inches of mulch on the orchard
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.

Fruit trees at Orchard irrigated by modified flooding:
bubbler and basin

Asparagus turning brown in the winter
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.

Applying compost to the raised beds
Cut down asparagus. Asparagus growth is cut to the soil surface when it turns yellow or brown. If this does not happen by the end of the month, cut the asparagus down to the soil surface.

Compost planting beds to be rototilled. Those beds which have not been planted should be prepped for next season. Use a high grade of compost to improve the soil to a depth of 12 inches. Incorporate a high phosphorus fertilizer in the planting row or in the backfill when planting transplants.

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.
Whitewash applied to fruit trees

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.

Borere control with a sharp knife
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.
Limb spreaders on a young apple tree

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.

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.

The Problem I Warned About on Pruning Pine Trees Just Happened

I said it might happen and it did.
This pine tree has a limb that broke in a
windstorm not too long ago. It is just
at the bottom of the trunk.

Thinning pine trees by removing smaller limbs from larger limbs (thinning the canopy) is NOT a good idea. This has been a relatively recent trend in tree trimming (I do not want to call this arboriculture) is done to reduce the potential that trees will blow over in high winds. Instead, thin the canopy  by removing entire limbs from the trunk to reduce wind damage and blowover . Here is why.

Plants grow both in length (called primary growth) and width or diameter (called secondary growth). When secondary growth occurs along a limb or trunk, progressively, as it get longer, then the limb or trunk exhibits "taper" or a gradual increase in girth along its length. This is good unless you are growing trees to use as telephone poles or for lumber.

A plant develops taper along its trunk or large limbs if the trunk or limb can bend freely in the wind as it is growing. The free movement of the tree trunk or limbs increases the degree of taper. If the trunk or limb is held so that it cannot move (staking so no movement occurs), primary growth increases but its growth in girth (consequently its degree of taper) decreases.

Here is the limb that broke

Taper also inceases if smaller, lower limbs are left attached to a limb or trunk. These smaller limbs, with leaves attached,  send carbohydrates manufactured in the leaves or needles back to the limb or trunk. This helps "feed" secondary growth causing more taper at areas closest to those small limbs. A distribution of smaller limbs along a trunk or limb causes an increase in its degree of taper. On the other side, removing these smaller limbs along a trunk or limb REDUCES the degree of taper.

The limb that broke is in the center of the picture. Notice
how little taper the limbs have. Leaving all the growth
at the ends of the branches also causes the limbs to have
a "weeping" effect.
When a trunk or limb bends, and it is tapered, the stress of the bend (shear) is distributed along a great deal of its length. If there is little taper to a limb or trunk, then the stress is localized at a very small portion of its length. When a limb is not tapered, the stress of bending causes the limb or trunk to "snap" (shear)  at its weakest part or where the majority of the "load" or stress is localized.

Here are three principles to follow to increase taper in a tree:
1. When planting a tree, make sure stakes are located as low on the trunk as possible. Tree stakes should keep the rootball or rootsystem stabilized, not the entire trunk. The trunk and limbs should be free to move in the wind if possible.

2. Remove stakes as soon as possible after the root system has become established. This should normally be one season or less. If it is longer than this then you may have a problem.

3. Leave smaller limbs attached to the trunk for three to five years if they are healthy and vigorous. Try to maintain a ratio of canopy length to pruned trunk of at least 2:1.

Monday, December 19, 2011

Fertilize Lawn in the Winter?

Q. I remember you said to apply fertilizer to a lawn around Thanksgiving. But during that time it was cold and the fertilizer bag says to water frequently.

A. Fertilizing is different from seeding. I recommend fertilizing tall fescue with a high nitrogen fertilizer around Thanksgiving. This helps keep the lawn green through the winter months. Once the fertilizer is applied, it should be watered in with a single, normal irrigation. If you haven't done it yet, it may not be too late. Pick a warm, winter day and apply a high nitrogen fertilizer.

            Weekly waterings after that will be adequate to move the fertilizer into the soil and made available to plant roots. High nitrogen fertilizer applied just before cold weather helps keep lawn grasses green and better looking for a longer time into the winter.

            Watering once a week after you apply a fertilizer is adequate for fertilizer but not adequate for seed. This is not time to seed the lawn. That has to be done when temperatures are still relatively warm but not too hot; usually from September 15 through October 15 or thereabouts.

Help Me Save My Lawn!

Q. I have some problems with my lawn and I sent you some pictures. I am a recent transplant here from Chicago and I am not sure how to manage this lawn and get it flush, green and thicker. The lawn has bare spots and the tree in the center of the lawn has roots on the surface of the soil. How should I repair this lawn? How do you manage a lawn here? Is this lawn savable? Was the tree planted too shallow? What is this green net in the lawn I found? I remember you said to apply fertilizer to a lawn around Thanksgiving. But during that time it was cold and the fertilizer bag says to water frequently.        

A. Thanks for sending the pictures. That really helps a lot. Yes, your grass is savable but there are some important things that you need to check out before we can proceed. I hope you understand the importance of water and if water is not applied appropriately it doesn't matter what you are trying to grow, it will not do well. The first thing you must do is check the irrigation system. These are the things that your irrigation system should do for your lawn if it is going to be successful here.

            From the look of the lawn it appears to be tall fescue. Make sure the irrigation sprinklers, pop-ups, rise 4 inches above the lawn. Some pop-up sprinklers are 2 inch, 3 inch and 4 inch. With tall fescue it is important that these are 4 inch since the lawn will be mowed at 2 inches or higher. 2 inch pop-ups are not adequate and you must replace them with 4 inch pop-ups. The pop-ups operate on a spring. You have to pull will pop up with your hands to measure the height or turn the irrigation system on.

Head to head coverage
            Next, when the irrigation system is on the water from one sprinkler should be thrown all the way to a neighboring sprinkler to get head to head coverage. 100% coverage or head-to-head is very important for sprinkler system to operate efficiently in the desert. Thirdly, when the sprinkler system is operating you should see droplets coming from the sprinkler and it should not be fogging or misting. If you see fogging or misting the from the sprinklers this is an indication that the pressure of the system is most likely too high.

Pressure regulator
            A pressure regulator would then be installed on your irrigation system to lower the pressure within the manufacturer’s suggested operating pressure which is usually somewhere around 40 or 45 PSI. Or you can replace the nozzles of the sprinkler pop-ups with pressure regulated nozzles. This may be a less expensive option for you since the nozzles are relatively inexpensive. The nozzle unscrews from the top of the pop-up. If the pressure of your system is 60 or 70 PSI you will definitely see some fogging if these are the older type nozzles. You should make sure that the nozzles are matched. This means that they all come from the same manufacturer with the same specifications or model.

            The pop-ups should be spaced such that the water from one sprinkler should be thrown far enough so that it hits the neighboring sprinkler. This is head-to-head coverage or 100% coverage. Making sure you have 100% coverage will give you better uniformity in the application of the water to your lawn.
Small triangular piece of lawn in upper right that makes the
lawn difficult to irrigate without water running into the
street, over watering the lawn or under watering the
small triangular piece

            I noticed on one of the pictures there is a small, triangular space as a part of the lawn. This will always be a problem for you since water cannot be applied efficiently and evenly to a small, oddly shaped space. The best shapes for lawns are square or rectangular since water use thrown by sprinklers in straight lines and distances varying from 10 to 18 feet depending upon the nozzle.

            As part of your maintenance program you should be checking to make sure the nozzles are not plugged and clear the grass around the nozzle. I would strongly suggest that you not let someone convince you to cut the lawn short around the nozzles instead of replacing them. Yes, this is an easy temporary and inexpensive fix to the problem that tall fescue must not be cut shorter than 1 1/2 inches or you will see weed invasion of your lawn in these areas. The principal weed that will invade your lawn in these damaged spots will be common bermudagrass.
Depressions in lawn around sprinkler due to a line trimmer
instead of replacing the two inch popup with a four inch

            Now the tree. The tree was not planted too shallow. This is an older tree. Because I could only see the trunk I could not determine what kind of tree it is but from the picture this is a tree which tends to have roots that grow toward the top of the soil. Or, the tree has never been irrigated deeply and so has grown its roots on the top of the soil where most of the water has been applied. Or, it can be a combination of the type of tree and shallow irrigations. Some trees are notorious for having shallow roots. The next question is whether the roots could be removed. This would be difficult to answer without knowing what type tree but it might be possible.

Differences in texture between a coarse textured tall fescue
like K31 and turf type tall fescue. The Kentucky 31 tall
fescue was seeded into the finer textured fescue to
save money, from an old slide of mine.
            It is also possible if the tree creates a lot of dense shade underneath it that the lawn will begin to thin due to a lack of light. In this case, the usual recommendation is to begin to remove lower limbs and thin the canopy of the tree to admit more light for the lawn. An option you might consider if you want the lawn to remain is to remove the tree. Another option if you want the tree to remain, is to remove the lawn and revert the landscape to a desert themed landscape.

            Fertilizing is different from seeding. I recommend fertilizing tall fescue with a high nitrogen fertilizer around Thanksgiving. This helps keep the lawn green through the winter months. Watering once a week after you apply a fertilizer is adequate but not adequate for seed. This is not time to seed the lawn. That has to be done when temperatures are still relatively warm but not too hot; usually from September 15 through October 15 or thereabouts.

            This time of year would be difficult to establish grass due to cold weather. You will now have to wait until around the end of February if you want to seed with tall fescue. When choosing seed to reseed the area, choose good quality tall fescue seed. It will not make much difference which seed you use but do not use inexpensive seed. Avoid K31 or Kentucky 31 tall fescue seed in this particular case. This is a pasture grass and not suitable for residential landscapes.

Plastic netting on a roll of tall fescue sod.
            General maintenance of a tall fescue lawn would be fertilizing on Labor Day, Memorial Day, Fourth of July and Thanksgiving. If you are mowing with a mulching mower and returning the clippings back to the lawn and then you can skip your Fourth of July application. The fertilizer that you use should be high in nitrogen, low in phosphorus and moderate in potassium. These represent the three numbers on the fertilizer bag. If you were to make a ratio of these numbers by taking the lowest number and dividing it into the other two the ratio should be 3:1:2 or 4:1:2. Examples might be 21-7-14; 15-5-10; 20-5-10, etc. These numbers do not have to be precise but they should generally be in those ratios.

            The green netting came with the sod when it was planted. The netting held the sod together. Do not pull on the netting. If you pull on the netting you may very well pull up the grass. Instead, cut the plastic netting and remove it. If someone pulled on the netting previously this may be a reason for the bare spots. I hope this helps answer some questions.