Of all the threats that spruce trees face in Michigan, few are more serious than needle cast fungus. An infection that starts spreading at the end of winter, this disease can severely weaken your trees while giving them a decaying, unattractive appearance. Only through a combination of precise preventative measures and targeted fungal treatment programs can you keep needle infections at bay and restore full health to your trees.
What is Needle Cast Disease?
Needle cast is a common name for rhizosphaera, a type of fungus that targets spruce trees. A common threat in much of the American Midwest, this disease slowly eats away at your needles. The longer you let it go on, the more needles your tree will lose.
As with most tree threats, controlling needle cast disease requires a combination of prevention and treatment. The following tips will help you stop infections from occurring and end them more quickly if they do happen:
Space Your Trees Out- Needle cast is more likely to spread if you have large numbers of spruce trees next to one another. By putting as much distance as possible between each tree in your yard, you make it harder for the fungus to attack any one plant. If a tree is infected, you can more easily isolate it and end the infestation quickly.
Water Regularly- Trees that don’t have sufficient water cannot fight fungal infections as effectively. By watering your spruce trees on a regular basis, you make it easier for the plants to shake off infections whenever they arise. Just be careful not to overwater them— the rhizosphaera needle cast fungus also needs water, so spreading too much of it makes an outbreak more likely.
Fertilize Your Yard- Besides water, your spruce trees need nutrients to fortify themselves against a needle cast fungus infection. Determine the best possible fertilizer for your trees given the soil quality of your yard, and then apply it on a regular basis.
Furnish Fungicides- No matter how strong your trees are or how well you’ve spaced them out, needle cast fungus may still manage to infest them. You can end such an infestation quickly by applying quality fungicides to all infected areas. Make sure to apply them exactly as instructed on the packaging; putting too much fungicide on or spreading it in the wrong places can damage your trees.
In addition to these strategies, it’s important to watch out for a needle infection and respond to it quickly. This is easiest to do if you know:
How To Identify Needle Cast DiseaseThe sooner you spot needle cast disease, the easier it is to get it under control. You should thus look out for the most common characteristics of the disease, which include:
Color- In the early stages of a needle infection, the tips of your spruce trees’ needles will look brown, red, or purple. This discoloration tends to spread over time, and it changes to a fire red and brown appearance in the latest stages of infection.
Timing- Typically, you’ll notice the earliest stages of a needle cast infection during the late winter or early spring. The fungus will spread gradually during the early part of the year until reaching an advanced stage toward the end of spring or beginning of summer.
Impact- If needle fungus is allowed to spread throughout your tree, it will eventually cause the needles to die and fall off. This will lead to serious shedding throughout your trees, impacting both their beauty and their health.
A needle cast outbreak is most likely if your trees have suffered drought stress or insect attacks, as these weaken their natural defenses against infection. Prolonged moist conditions, which are common in Southeast Michigan during the spring, also make it easier for it to spread. If your yard has these conditions or has suffered needle cast infestations in the past, you should be especially vigilant about this disease.