Zimmerman pine moth (Dioryctria spp.) is an injurious pest of pine trees in Nebraska. This insect attacks Austrian, scotch, jack, ponderosa, and white pine trees, and occasionally spruce. Zimmerman pine moth larvae damage trees by boring and tunneling beneath the bark of the trunk and branches, usually where the branch is attached to the trunk. Tunneling damage can girdle the trunk or branches, and physically weaken the tree. Infested trees show branch dieback, deformed growth, and may die.

The Nebraska Department of Agriculture (NDA) is responsible for assuring that the nursery stock distributed in Nebraska is free of injurious plant pests. Because Zimmerman pine moth is such an injurious insect, nursery growers and dealers need to be aware of the consequences of an infestation. When a Zimmerman pine moth infestation is detected in a nursery, an intense amount of management must occur. Control can only be achieved through a combination of proper sanitation practices and correctly timed chemical treatments.

The following policy and procedures have been adopted by NDA concerning Zimmerman pine moth infested nurseries:

1. Nurseries must adequately mark blocks/rows of pine trees with signs, so the inspector can refer to these blocks on the inspection report.
   
   
2. In nurseries where Zimmerman Pine Moth has been detected, sheared Christmas trees won’t be certified as nursery stock if the inspector can’t adequately see into the trunk area for the inspection.
   
   
3. Trees found to be infested with Zimmerman pine moth will be painted with orange spray paint by NDA inspectors, and are required to be rouged out of the field.
   
   
4. If the inspector finds that 20% of a block is infested with Zimmerman pine moth, the entire block is restricted and withdrawn from distribution, and no trees in that block are certified. NDA has the right to post signs indicating blocks which are totally restricted.
   
   
5. Two insecticide treatments for the control of Zimmerman pine moth will be required at nurseries with known infestations. The first treatment will need to be applied during early April, and the second treatment will need to be applied during early August. The April treatment is effective against the overwintering larvae, as they exit their hibernaculum and begin actively feeding in the spring. The August treatment targets new larvae, which hatch in August and begin feeding.
   
   Permethrin or bifenthrin products are currently recommended for insecticide treatments. As with all pesticide treatments, be sure to apply according to the label instructions.
   
   
6. The insecticide should be applied to the trunk and branches from the top to the bottom of the tree, so the bark becomes thoroughly wet to the point of run off. Only certain types of spray equipment will be accepted for treatment purposes. Aerial application will not provide adequate coverage. Spray equipment should deliver the proper droplet size to adequately drench the trunk area. Treatment records must be maintained, which include date applied, chemical used, amount of chemical used, and applicator. These records may be audited by NDA.

If you have any questions regarding this policy, please contact NDA at 402-471-2351.