Identify the Type of Tree First
The first step in identifying the issue is determining the type of pine tree, as some trees are more susceptible to certain fungal diseases than others. If you don’t know which type of tree it is, look at the needle bundles. Those with two bundles are red, jack, or Virginia pines. Those with three needles are pitch pines or loblolly pines. Those with five needles are white pines or sugar pines.
Send a Sample to a Diagnostic Laboratory
Remove a small branch from the tree and send it to a local diagnostic laboratory (your state’s forestry service can help you find one). This will help pinpoint the exact fungal disease attacking your tree, helping you make better decisions regarding ongoing treatment.
Pro Tip: Brandon Maltby, a tree specialist featured on Ask This Old House, recommends sending samples to a diagnostic lab as standard practice: “I’m gonna take a sample off this tree. It’s just good practice. I know we’re dealing with a fungus, but I want to know exactly what type of fungus. So, I’m gonna send this out to a diagnostic lab. They’re gonna get a look at it and tell us exactly what we’re dealing with. That way, we’re not surprised by anything.”
Expect the turnaround from a diagnostic lab to take about two weeks. Once you have the results, you and your arborist can develop a targeted management plan—whether that involves a specific fungicide treatment program, pruning, or other interventions—rather than guessing at a solution.
Remove the Pine Needles and Mulch
Pine tree fungal diseases often return year after year because the infected needles fall to the ground under the tree and their spores are released the following year, reinfecting the tree. To combat this, you need to clean up the fallen needles and mulch on the ground and remove them from the site completely. They should not be discarded anywhere near the property or composted. They must be thrown out.
The best way to remove the needles is to use a cultivator—a stiff, steel rake with tines that can dig down into the soil and remove the needles and the mulch. Make sure to bag the waste and take it to a refuse center to prevent the spores from reactivating nearby.
Use Organic Leaf Mulch
Replace the existing mulch with organic leaf mulch. Leaf mulch will restore nutrients to the soil as it breaks down while also allowing air to reach the soil and the tree’s roots. Applying leaf mulch is simple, as it can be thrown under the tree by hand and doesn’t require any specific tools or techniques.
When applying leaf mulch, spread it to a depth of about three inches, but keep it at least three inches away from the trunk of the tree. Piling mulch against the trunk creates what’s known as a “mulch volcano,” which suffocates the root mass and can cause bark to deteriorate—potentially killing the tree. Always ensure the root flare at the base of the trunk remains visible and exposed to air and sunlight.
Pro Tip: In a This Old House segment on mulching, landscape contractor Jenn Nawada explained the benefits of organic leaf mulch: “The leaves have been composted, turned over and over, and it’s breaking down towards the soil. So it’s just going to add all those nutrients into the existing plants.”
Install Drip Irrigation
Install drip irrigation around the base of the tree. Drip irrigation is easy to install, requiring just a pair of sharp shears and a torch. Connect the tubing by heating the end of the tube slightly and inserting a barb fitting between the lines. Run the lines 10 to 12 inches away from the tree trunk, and once you’re satisfied with the pattern, secure the line with sod staples.
Resources
Arborist assistance provided by Maltby and Company.
Keep the ground clear of pine needles to prevent disease from spreading and infecting other trees. Use an organic leaf ground mulch to add nutrients back into the soil and root system.
To install drip irrigation, start by laying out the irrigation line 10-12 inches away from the tree trunk to avoid the root system. Use sharp hand shears to cut the irrigation line. You may need to use irrigation line connectors or fittings to create longer runs. Use a torch to heat up the end of the irrigation line. This will make the material flexible enough to make your connection. It’ll create a tight seal around the connection once the line cools off.
Once you’ve laid out the line in your desired pattern, secure the line in place using sod staples.
