Xtremehorticulture

Root Rot on Pines?

 Q. I have several very large pine trees that have been in ground since 2002. Due to heavy winds, one was felled, and the trunk broke. Upon inspection, it looked like root rot! Can you advise how much water these trees need in winter and summer. I want to be sure the see does not happen to others. A. Make sure the trees have water applied to a wide area, equal to about half the spread of their canopies. Tree roots follow applied water in the desert. Pine trees are relatively deep rooted. For this reason, apply water to them deeply. However, if the soil is hard, and the water applied too rapidly, the water may begin puddling and the tree can blow over easily. Watering plants in the desert tells them where you want their roots to grow. The roots of any large tree near a wall is a “recipe for disaster”. This large pine tree eventually heaved this wall when the roots “grew looking for water”. The roots heaved the wall. The other problem is watering. If they are given small drinks of water frequently (think planting in lawns) they develop roots that are shallow and will not hold them upright during strong winds.  When planting pine trees it may be a good idea to plant other smaller shrubs around its canopy. Pine tree roots will grow where the shrubs area as well and help support it. Unless you know what you are doing, it may be a bad idea to have a pine tree planted all by itself surrounded by desert soil that is not irrigated. These trees will blow over.  Place plants around the pine tree that are throughout its canopy as it grows larger. Putting irrigated shrubs around pine trees helps the pine tree roots to grow into the surrounding soil and become more firmly anchored. It is not something mystical about the surrounding plants. It is because these plants are irrigated, and they share water with the pine trees.

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Loss of Pine Limbs May Be Light or Water

Q. I have a large pine tree in a natural area losing limbs from the bottom up. It’s needles are browning and dropping. I don’t water the tree much at all, but I have a water channel flowing 3 feet away on one side of the tree. The channel is mostly filled with moving water and is about 1 foot wide. A. It’s probably either water or light issue. Not enough light because trees are planted too close together will also cause lower limbs to die and drop. Sometimes light is not considered.  Pine trees planted four to six feet apart are too close together and lower limbs will die as they age. An open canopy pine tree signaling that maybe the tree was either not receiving enough water OR it cannot get the applied water to the needles due to trunk damage.             My guess is that it’s water related; not enough. An easy way to find out is to put a sprinkler on the end of a hose and give the tree one to two hours of water once every three weeks to a month. I would use a non-oscillating sprinkler and adjust it to about 8 feet wide. Use a four foot long piece of rebar to adjust how many minutes to water. Hose-end sprinkler.             There are two ways that I use to tell if a pine tree isn’t getting enough water; 1) I look at the amount of new growth and 2) its canopy density. On well-watered, fertilized smaller pine trees to about 20 feet tall, I like to see about 18 inches of new growth and a solid canopy density. On older well-watered pine trees 40 to 60 feet tall the growth will be a lesser amount, perhaps 8 to 12 inches, but the trees still have a dense canopy. If growth is 2 to 4 inches when the pine tree is older then growth is not enough. Measure growth at the end of May after spring growth is finished.             Pine trees with drought problems usually grow 2 to 4 inches in length each year. This small amount of growth translates into a very open canopy. Because pine trees can have other problems as well such as borers and woodpeckers (sapsuckers), I inspect the trunk for this kind of damage as well. A tree trunk with extensive damage by borers or woodpeckers may also show signs of drought. Pine trees with only a few inches of new growth each year and an open canopy usually suggests drought.

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Watering Pine Trees – Water Deep!

Q. I recently moved into a condo that has pine trees on the property. Some of them look like they aren’t growing much but those still in grassy areas look much better. Some other pines have branches that are dying back. Do I need to supply water to these trees? The very new growth in the spring of pine trees are called “candles” because they look like candles. All the new growth for that pine tree is contained in that candle. If water is available to the tree, candles will stretch and get big. If water is limited, the candles will not stretch and the new growth will stay small.Notice the buds at the base of the candle. I will talk about these buds in the next picture. A. All of this is not simply a water issue. There is probably a disease problem going on as well. But first things first. Pine tree branch growth, and how dense the tree is, has a lot to do with how much water it receives in the spring and early summer months. Just as important is how deep the water drains in the soil, to encourage deep root growth, after it’s applied. Branches of pine trees are in the whorls along the trunk. In the picture above, you can see the buds at the base of a candle. Those buds will grow into limbs that are in whorls around the trunk.             Most native pine trees grow along canyons or stream banks where water is plentiful in the spring months and less available later in the season. Water availability coincides with spring growth which in turn increases the tree density.             Water pine trees deeply, particularly in the spring months. How deep? Water should drain 24 to 36 inches into the soil each time it’s watered. To make sure it’s deep enough, measure this depth with a long thin metal rod like a piece of rebar. Plenty of water this time of year helps push new growth. This new growth supports the needles responsible for a dense tree canopy. Deep irrigations are important later in the year, but less often, to maintain this density. This blow over can happen to trees when they receive shallow irrigations and shallow applications of water. This is a mesquite but it can happen to pine trees, and does. Water large trees deeply to avoid blow over during strong winds. With deep irrigations, roots will grow deeply.             Lawn watering only applies water about eight or 10 inches deep. This is not deep enough for large pine trees as they get bigger. Watering lawns with shallow irrigation may keep the trees denser but it doesn’t encourage the deep roots needed during strong windstorms. Besides the lawn water, large pine trees should get periodic deep watering as well. Pine trees in lawns may look full but they usually will blow over during windstorms as they get bigger. Aleppo Pine Blight is classified as a disease but there is no known pathogen or living disease agent associated with it. In extreme cases it can cause entire branches to die. But the tree with this problem should be and Aleppo Pine, not a different type of pine.             Branch dieback of pine trees is usually a physiological disease that cannot be cured called Aleppo Pine Blight. In most cases, new pine needles in the spring replace the dead needles lost during the winter months.

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