Hello Carla, 

I've prepared a writeup for you with some information on the issues you're experiencing.

Understanding Western Redcedar Decline

Western redcedar (Thuja plicata) is currently facing a complex "dieback" phenomenon across much of the Pacific Northwest. It is vital to look at the environmental causes before investing in expensive chemical treatments.

1. The Primary Cause: Climate Stress

Evidence suggests that redcedar mortality is rarely caused by insects alone. Instead, a changing climate is the primary driver:

The "Straw" Effect: During extreme heat, the tension in the tree’s water-conducting tissues can become so great that the "columns" of water break—much like air getting into a straw. This makes it impossible for the tree to move water to the top, leading to tree health issues.

Habitat Shift: Many redcedars are now growing in areas or microclimates that are no longer sustainable for them as our summers get hotter and drier.

2. Insects as "Secondary" Factors

The insects mentioned by the tree company—such as cedar bark beetles or amethyst cedar borers—are almost always secondary pests.

The "Cleanup Crew": These insects are chemically attracted to trees that are already weakened by drought.

Treatment Reality: If a tree is "near dead," insecticide treatments (even professional ones) often fail. A damaged vascular system cannot effectively transport the chemical to where the insects are feeding.

3. DIY Treatment & Selecting Products

If you want to try treating the remaining two trees yourself to save money:

Check the Label: You’ll want to make sure the product you choose specifically lists conifers or evergreen trees on the label.

Follow the Rates: For the best results and to protect your health and the landscape, you should follow the label's application rates and safety instructions (like wearing gloves) exactly as written.

Location Context: Most over-the-counter products are designed for "ornamental" or "home landscape" use. If your trees are in a more natural, "forested" patch of your property, double-check the "Directions for Use" section to ensure it fits that setting.

4. Cultural Care: The Right Way to Water

Watering can help, but the method is vital.

Avoid Shallow Watering: Frequent, shallow watering can actually be detrimental. It encourages surface roots that are easily scorched and can lead to root rot in certain species.

The Deep Soak: The best approach is infrequent, deep watering during the driest parts of the summer (July through September). This encourages deep, resilient root growth.

5. Long-Term Strategy

Sometimes, the most cost-effective path is to move on. That $1,400 might be better spent on:

Hazard Reduction: Removing a dying tree early prevents it from becoming a falling hazard to people, your home, or power lines.

Replacement: Planting younger, more drought-resilient species—like Incense-cedar, Oregon White Oak, or Ponderosa Pine—which are much better adapted to our current climate trends.

I hope this information helps you.