Preventative spraying of Scotch Pine and Blue Spruce

Asked March 19, 2016, 10:28 AM EDT

My Scott Pine was attacked by some kind of dark brown beetle 3-4 years ago as evidence of the pitch tubles (not popcorn looking more cone shaped). Since then an arborist has recommended and has been spraying for Zimmerman pine moth. Is this a necessary preventative spray to keep the tree healthy post the attack? Are there recommended preventative sprays for Scott Pine and Blue Spruce trees in Aurora, CO? Thank you.

Arapahoe County Colorado trees and shrubs

1 Response

Below is a picture of a pitch mass made by the Zimmerman Pine Moth. It is described in the literature as 'popcorn-like'. Zimmerman Pine Moth will infest Scots, ponderosa and Austrian pines. Austrian pines have been the most commonly infested. If the pitch mass and any insect activity has been positively identified as being the Zimmerman Pine Moth then the insect is most vulnerable to controls when larvae are active and exposed on the bark in spring and late summer. Drenching trunk sprays penetrate the bark scales. Apply them around mid-April or in August to kill active, exposed larvae before they enter tree trunks. Permethrin or bifenthrin applied during early April to early May is currently recommended for trunk sprays. Preventive insecticide sprays, applied to the trunk before the caterpillars begin tunneling, are best applied in April or early May.

You could have your trees re-evaluated by an independent
certified arborist who can physically look at your trees and give recommendations regarding continuing the preventative sprays.

Here is a link to the CSU Extension Fact Sheet for Zimmerman Pine Moth:

Popcorn-like pitch masses

I included this Fact Sheet to provide you with information to aid you in diagnosing the presence of Zimmerman Pine Moth. There are a number of bark beetles and other insects that can have pitch tubes present so it is important to ensure that a proper diagnosis was made.

Insects, such as the Zimmerman Pine Moth, can attack stressed trees. Keep your trees as healthy as possible. In the last couple of years we have had weather phenomena that have stressed many trees in the Front Range area. Some trees are still vulnerable to insect damage and disease. Continue to look at the overall health of your trees, shrubs and
landscape plants.

If we have a period of time during the fall and winter with no moisture it is advisable to water your trees. The following is a link to "Fall and Winter Watering":

The Zimmerman Pine Moth should not harm your Blue spruce.