We recommend the Portle Tips for thick-barked hardwoods such as elm and eucalyptus. And a pro tip…inject off to the side of the bark or angle the tip behind the bark. Portle Injection Tips are designed for conifers and hard-to-treat hardwoods and beneficial when injecting tough-barked hardwoods such as hackberry and hickory or when the bark of any type tree becomes harder to penetrate when making late summer or fall injections. The short Portle Tip works well for injecting Sycamore and London Plane trees that can be difficult to inject with the Wedgle Tip. For more information, click here.