What is the cause of the blue spruce tree dropping needles?
There are several reasons why the needles of a tree turn brown.Before action is taken on saving the tree, it is important to find out why the needles are dropping as this will determine the necessary course of action.Natural causes are the most common cause of needle drop.Needles can stay on a tree for up to 3 years before dropping.There are environmental factors that can affect this cycle, for example, a tree that is under stress from the weather can increase needle drop.The trees that were under water last year may be showing stress for the first time this spring.
If needles are dying at the tips of the branches, you may be dealing with a disease called cytospora canker, which is the most common cause for needle drop on Colorado blue spruce.The cankers are dead areas at the base of the branches.The cankers produce a white substance that runs down the tree.If the disease is detected early, the tree can be saved by Pruning and maintaining tree vigor through a fertilization schedule and watering during dry periods.
rhizosphaera needle cast is a common tree disease.Needles may look yellow in the late summer and turn brown in late winter or early spring with needle cast.Black dots are the best evidence for needle cast.There are black dots that can be seen with a magnifying glass.Severe needle loss can occur if a tree is infected for 3-4 years.Maintaining tree vigor is the best way to treat needle cast.Once the presence of rhizosphaera is confirmed by an expert, a fungicide can be sprayed.
If the needles are turning yellow, they should be inspected for spider mites.If you hold a white piece of paper under a branch and shake it vigorously, you can detect these.There are small black specks on the paper if there are mites.If you have a small spider mite problem, spraying the tree with a garden hose may be all you need.Chemical control may be required for a bigger problem.