Start Fighting Against Invasive Shot Hole Borer with TREE-äge® R10 or TREE-äge® G4 and Propizol®

Preventative treatment with TREE-äge® R10 or TREE-äge® G4 prior to initial ISHB attack is the recommended management strategy. In addition, a systemic injection of Propizol® will protect trees from the fungi introduced by the beetle. Treatments should be reapplied every 2 years. Keep your client’s trees protected from this invasive, destructive pest with Arborjet.


The Invasive Shot Hole Borer (ISHB) is an exotic ambrosia beetle that was first detected in 2003 in Southern California.

It is currently found in L.A., Orange, San Bernardino, western Riverside, and San Diego Counties. The “ambrosia” name refers to a symbiotic fungus that is carried by the female in special organs in her mouth parts. The fungus is grown in the beetle galleries and both the adult beetles and larvae feed on the fungi. The adult beetles are very small, ranging from 0.05 to 0.1 inches in length. They come in a range of shades between black (females) and brown (males) coloring. While this beetle attacks a large number of plant species, the majority of which are hardwoods, it can only reproduce in 31 species including maples, sycamore, oaks, willows, alders, and avocado.

The characteristics of ISHB attack and fungus infection differ among tree species. The beetle commonly attacks the main stem and larger branches of trees and shrubs, but injury can be found on twigs as small as 1 inch in diameter. The beetle produces a very precise, perfectly round, tiny (< 0.1 inches in diameter) entry hole in most trees. Wet staining and discoloration on the bark of the main stem and branches are early symptoms of beetle attack. Depending on the tree species attacked, ISHB injury can be identified either by staining, gumming, or a sugaring response on the outer bark. Infection with the fungus can cause leaf discoloration and wilting, dieback of entire branches, and tree mortality.


Here at Arborjet® we have a proven and effective treatment solution to control this devastating insect. To treat ISHB, Arborjet uses systemic micro-injectable products; TREE-äge G4 or TREE-R10 and Propizol. “In field trials,treatments showed significant control in the management of ISHB attacks,” states Don Grossman our Technology Advancement Manager & Entomologist here at Arborjet.

The most significant damage occurs from May through October so if ISHB is found near or on trees under your care, treatments should be made immediately. Generally, the best seasons for injection are spring and fall, since the best uptake occurs when trees are actively transpiring, but treatments can be made at any time of the year when there is good soil moisture to encourage translocation of the systemic formulations.

Trunk injections with insecticide or combined with fungicide will distribute upward in the tree within 4-6 weeks with adequate soil moisture. For trees in natural, non-irrigated areas with questionable soil moisture, consider using NutriRoot to enable trees to extract water from the soil, reducing the need for watering, and resulting in faster and better movement of systemic products even in drought conditions.

While this beetle can attack over 300 plant species, the majority of which are hardwoods, it can only reproduce in 65 species, including maple, sycamore, oak, willow, alder, and liquidamber.


©2020 Arborjet, Inc. Important: Always read and follow label instructions. Some crop protection products may not be registered for sale or use in all states or counties. Please check with your state or local extension service to ensure registration status. TREE-äge® Insecticide is a Restricted Use Pesticide and must only be sold to and used by a state certified applicator or by persons under their direct supervision. TREE-äge® is a registered trademark of Arborjet, Inc.