5 Common Fir Tree Diseases to Watch Out For

Nothing is more heartbreaking than watching your beloved fir tree waste away, and ultimately perish, from any one of the many common diseases that plague them. Unfortunately, for tree owners, fir trees are vulnerable to many ailments. Fortunately, however, with a little diligence and the help of a good tree service, you can often arrest the progress of these diseases in their tracks.

The first step is to educate yourself; usually, it’s easy to recognize the signs and symptoms of a common tree disease if you know what to look for.

Here are five of the most common fir tree diseases and how to recognize their signs and symptoms:

Swiss Needlecast

A disease that only affects Douglas fir trees, Swiss needle cast has begun to spread more and more in the Pacific Northwest. Caused by a fungus called Phaeocryptopus gaeumanni, Swiss needle cast is spread by spores, which are spread by the wind during the cold and wet months of the year. The spores will take hold in the needles of the fir trees, ultimately choking the spread of water and nutrients and stunting the growth of the tree.

The first signs of Swiss needle cast usually show up in springtime. If you have Douglas firs on your property, get in the habit of checking under the needles every year in the early months of spring. If Swiss needle cast has begun to take hold on your tree, you’ll notice black lines appearing on the underside of the needles. Over time, the needles will yellow and eventually fall off. If the problem is not addressed, the disease will leave your tree stunted and sickly.

Treatment for Swiss needle cast requires the help of an experienced tree specialist, such as the ones from Mr. Tree. Air circulation goes a long way towards halting the spread of the disease, so your specialist may decide all your tree needs is a pruning. You may also need to quarantine younger trees to prevent them from becoming infected; saplings and new trees may not be able to recover from the disease.

White Pine Blister Rust

Another fungal disease, white pine blister rust, has been found in 38 states and can affect all species of North American white pines. Native to Asia, this fungus was introduced to the United States in the early days of the twentieth century. It’s particularly troubling for trees in high elevation areas. As with Swiss needle cast, this disease is of particular concern for saplings and other younger trees.

The first visible signs of white pine blister rust are often swollen branches. This is a sign that the rust has taken hold in the twigs and branches of the tree. Eventually, orange cankers will form on the twigs, branches, and needles of the pine tree, ultimately killing them. You may also notice streams of resin seeping out of the tree in the diseased areas. The biggest risk from this disease is if it infects the main stem of the tree. If this occurs, it can lead to topkill and the death of the entire pine tree.

This disease can spread very slowly, but in small trees it can cause a great deal of damage in just a few short years. Pruning infected areas and quarantining sick trees may be your only option. Contact the tree specialists at Mr. Tree if you think your pine tree is infected with blister rust.

Insect Infestations

Not a single disease, but a problem that can be caused or exacerbated by other illnesses, you must learn to recognize the signs and symptoms of an infestation in your tree. In conifer trees, there are several pests that can cause problems. These problems can range from damaging the tree and rendering it unsightly, to ultimately killing the tree.

Common enemies of fir trees in the United States include bark beetles, which are known to girdle even healthy trees as they lay their eggs, and Douglas-fir beetles. Douglas-fir beetles tend to seek out trees that have already been weakened by other diseases; they’ll move in and begin laying eggs. However, if there are no weakened trees available, these beetles will then seek out a healthier tree. Termites are another common pest species; you can recognize the signs of a termite infestation by the tell-tale sawdust tracks they leave scattered about your tree.

If you think your tree is infested by harmful insects, you may be able to eliminate them with a topical pesticide. However, this must be done with great care, because if it’s handled improperly you can harm the tree. As always, it’s best to contact your tree care professional if you are unsure.

Dwarf Mistletoe

The dwarf mistletoe is a small flowering plant that takes hold on pine trees, drawing away their nutrients in a parasitic relationship. While a small mistletoe plant is generally not harmful to the tree, they can overgrow and eventually develop large clusters, which over time can stress the tree to the point of death.

An infection of dwarf mistletoe begins innocuously enough, with a slight swelling of the bark at the site of infection. As the parasitic plant grows, you will notice small yellow, green, or brownish shoots protrude from the infected area. Over the course of a few years, the mistletoe will firmly take hold and can severely harm, or kill, the tree.

Pruning infected branches can be a possibility, however, in the case of a more severe infection, you may need to remove the entire tree to prevent the mistletoe from spreading to other nearby trees.

Sudden Oak Death

Certainly the entry on this list with the most alarming name, sudden oak death is caused by a fungus called Phytophthora ramorum. This pathogen infects the tree through the soil, causing a blight that can kill off the leaves and twigs of your fir tree. The name “sudden oak death” is certainly fitting when it comes to oak trees. Fortunately, if you have fir trees, the lethal action of the pathogen acts much more slowly, allowing you to work to solve the issue.

You will notice cankers forming on the trunks of your trees, as well as dieback of the needles and branches, if your tree has become infected by Phytophthora ramorum. If you notice any of these symptoms, contact a tree professional immediately because the fungus can easily spread to many vulnerable trees in your area and lay waste to them.