How to Get Rid of Those Pesky Borers on Your Arizona Cypress Tree

If you’ve noticed small holes sawdust-like debris dead branches, and other signs of damage on your Arizona cypress, you’re likely dealing with a borer infestation. Borers are the bane of cypress tree owners everywhere, tunneling under the bark and compromising the health of affected trees. But never fear – with persistence and the right techniques, you can get rid of borers and restore your tree’s beauty. This comprehensive guide will walk you through the process step-by-step.

Identifying Borers on Arizona Cypress Trees

Before treating an infestation, it’s important to confirm borers are in fact the culprits behind the damage. Here are the most common signs of borers on Arizona cypress trees

• Small holes in the bark, typically around 1/8″ in diameter or less. These are entry points where adult borers laid eggs.

• Sawdust-like frass on the bark surface or base of the tree. This debris is left behind as borers excavate their tunnels.

• Dead branches with loose, cracking bark. Dying tissue often indicates larval feeding.

• Wilting, yellowing, or browning foliage. Borer damage can disrupt nutrient flow.

• Sectioned bark: borers often remove bark in distinct patches.

Take a close look at your whole tree, especially the trunk and main branches near the base, for these symptoms. If you spot them, it’s time to start treatment.

Removing Borers Manually

At the first sign of infestation, taking swift physical action can help control borer numbers. Here’s how to remove borers manually:

• Using a sharp knife, chisel, or pruners, cut away any loose, cracked bark to expose tunnels.

• Dig out larvae, pupae, and adults using a flathead screwdriver or knife. Dispose of them.

• Cut off and dispose of heavily infested branches or even portions of the trunk, if necessary.

This hands-on approach allows you to eliminate many borers. But you’ll likely need other treatments too for full control.

Applying Beneficial Nematodes

One of the safest and most effective treatments for cypress borers is the application of beneficial nematodes. These microscopic roundworms seek out and kill borer larvae in their tunnels, providing natural pest control. Here’s how to use them:

• Choose a nematode product designed for tree borer control, like Guarding Against Borers.

• Mix according to label directions using room temperature, non-chlorinated water.

• Use a pressure sprayer to completely soak the trunk, branches, and surrounding soil.

• Apply in spring and fall when soil temps are between 60-90 ̊F.

• Repeat every 2-3 weeks until infestation subsides.

Nematodes can provide season-long protection with repeated use. Combine them with other treatments for maximum impact.

Using Horticultural Oils

Unrefined horticultural oils applied directly to the bark can also help combat borers in Arizona cypress trees. The oil’s coating suffocates eggs, larvae, and adult beetles on contact. Here are some tips for using horticultural oils:

• Select a highly refined, plant-based oil like Bonide All Seasons Oil.

• Mix according to label directions. Use caution, as oils can burn foliage.

• Use a paintbrush to coat bark, especially in crevices and around borer holes.

• Apply oil every 1-2 weeks during spring and summer for preventative protection.

• Reapply after rain or high winds.

Oils are most effective on young, newly hatched borers. Hitting them early improves control.

Calling in Beneficial Predators

In addition to directly treating the tree, introducing natural predators of tree borers can provide biological control. Some options include:

• Woodpeckers: Attract these voracious bark borers hunters with suet feeders.

• Green lacewings: Their larvae consume borer eggs and small larvae. Use pheromone boxes to lure them in.

• Parasitoid wasps: They lay eggs inside borer larvae, killing them from the inside out. Create small mud puddles as water sources.

• Entopathogenic fungi: Spray trunks with B. bassiana fungus to infect borers.

• Tachinid flies: Their maggots parasitize borers. Plant pollen and nectar sources like angelica or goldenrod to establish populations.

Encouraging a diversity of predators provides round-the-clock protection.

Preventing Future Borer Attacks

Once you’ve eliminated an active borer infestation, be proactive to prevent the pests’ return. Here are some key tips:

• Maintain tree health with proper water, fertilization, and timely pruning. Healthy, vigorous cypress trees resist borers.

• Wrap trunks of young trees with burlap or hardware cloth to create a physical barrier against borers.

• Apply preventative treatments like horticultural oils or beneficial nematodes each season.

• Monitor trees vigilantly for early signs of borer presence like small holes or frass. Catch infestations before they escalate.

• Remove and destroy severely infested trees to prevent spread.

With persistence and an integrated approach, you can protect your landscape investment and outsmart those destructive borers. Don’t allow them to damage your beautiful Arizona cypress trees!