When setting up a sprinkler in your garden, ensure that the water spray does not hit the trunks or canopies of nearby trees. Although grasses and plants benefit from having water sprayed directly on and around them, the same is not true for trees. In fact, doing so could harm or even kill a tree.
Water Droplets Carry Fungal Infections
Fungal spores rely on wind, soil movement, such as that caused by machinery, and water droplets to spread from one place to another. Sprinklers then, provide fungi, which live in the soil, with a means of infecting nearby plants and trees. This is bad news then if your sprinklers are covering a nearby tree's trunk and foliage with water several times a week.
Fungi such as anthracnose, a fungal disease that attacks the roots and foliage of trees, will be able to attack your trees if your sprinkler provides them the access they need. Tree trunks do not absorb water. Trees take in most of their water through small feeder roots, most of which are out at a tree's drip line.
Excessive Water Causes Rot
If a tree has a small hollow or has a split area where multiple trunks meet, a buildup of water can cause the tree to rot. This rot will attract pests and diseases, both of which will weaken the tree further. If the rot spreads, the tree will become a hazard in bad weather. A steady stream of water from a nearby sprinkler then will only make things worse.
Sprinklers Can Kill Palm Trees
Despite their name, palm "trees" are not trees. In fact, palm trees are more closely related to grass than they are trees. This is because unlike trees, which have large root systems that are often larger than their canopies, palm trees have small, shallow roots — like grass. However, the most important difference in regards to sprinklers is that palm trees don't have bark.
The bark of a tree offers a layer of protection, allowing the tree to heal should it sustain a wound. However, because palm trees don't have any bark, they cannot heal should they sustain trunk damage. Imagine then, how much damage a sprinkler could do, even at low pressure, if its stream regularly strikes the same area of a palm tree's trunk. If a substantial area of a palm tree's trunk is damaged, it will eventually die. You should remove badly damaged palm trees before their trunk rots as they may soon collapse, possibly injuring someone.
Should You Remove Sprinkler Damaged Trees?
Trees that have been damaged by sprinklers can be saved if they are treated quickly. If disease is the issue, your best bet is to hire an arborist who will be able to both identify and treat the disease. Some diseases can be eradicated with fungicide etc. However, not all diseases are curable though they may be manageable. You'll need to decide whether you want to keep the tree and manage the disease, or remove the tree and plant another. However, bear in mind that once you remove a diseased tree, the disease may remain in the soil in the area where the tree once stood.
Sometimes, trees suffering from disease or trunk damage die quickly, within weeks or months. In this case, it is best to remove the affected tree since it will soon become a safety hazard once its dead branches become brittle and easily snapped in high winds. Tree removal services can help.
If you want your trees to benefit from your sprinklers, spray the area around your trees, not the trees themselves. That way, you can keep your trees well watered while protecting them from fungal diseases and trunk damage.