Nevada's state tree is being attacked by two native insects that have partially defoliated about 700,000 acres, according to aerial survey data. The pinon needle scale and pinon needle sawfly have succeeded in causing many of Nevada's pinon pines to lose much of their foliage.
The pinon needle scale looks like white, brown or black spots on affected needles.
Scale insects suck most of the "juice" out of the needles causing older needles to die and drop off. The scale is best treated with horticultural or dormant oil in late fall through the winter months before any new growth begins in the spring. Some rural areas have significant pinon needle discoloration and damage such as Douglas County's Topaz Ranch Estates.
The other insect eating needles is the pinon needle sawfly. The best time to treat for this insect is in the spring as it begins feeding in the caterpillar stage.
The caterpillars are light green in color with black heads and feed in groups on the trees needles.
It overwinters in the needles as eggs emerging as caterpillars in the early spring. There are several registered insecticides including carbaryl and pyrethroids that will kill the feeding caterpillars. For all insecticide applications be sure to read the pesticide label before applying and follow all label directions. It is illegal to apply a pesticide contrary to its label requirements.
Many of the singleleaf pinon pine insects and diseases that can cause significant damage or mortality to pinon pines can be found in an online publication that NDF and University of Nevada Cooperative Extension cooperatively published in 2003 at the following Web site: www.unce.unr.edu/publications/files/nr/2003/EB0302.pdf.
Anyone with pinon pine tree acreage who needs assistance with determining what is causing the damage and recommended treatments should contact Nevada Division of Forestry's forest health specialist at 684-2513 or gdurham@forestry.nv.gov.
