State forestry officials have issued a forest health alert because of the effect Pinyon needle scale, a native insect, has on pinyons.
Pinyon needle scale, a native insect that defoliates and kills pinyon pine, was identified last year mainly throughout southeast Payson.
Most likely to die from the effects of the insect are pinyons growing on drier rocky outcrops, south and west facing slopes and transitional zones between pinyon-juniper and grassland vegetation types.
In addition, the insect was identified for the first time in the Beaver Valley Estates area just north of Payson in September, said Bob Celaya, Forest Health Specialist, Office of the State Forester.
Female scales have emerged from their over-wintering stage on the needles in both of these areas.
Very noticeable clusters of yellow eggs held together in loose, white, cottony webbing have been laid by the females mainly in branch crotches, along the underside of branches, on the trunk, and at the base of the tree. The females die shortly after egg laying is completed, he said.
Heavily infested pinyons can be easily detected by the yellow or orange discoloration of the older needles toward the back of the branch.
The needles are covered with small, black, bean-shaped scales which pierce the foliage and remove the sap, causing the needles to discolor, dry, and fall off. Small trees may be killed within a few years, whereas, larger trees may lose one or more branches and may take years to die, Celaya said.
Controlling the insect
Control of this stage of the insect involves several steps:
- Washing the eggs off branches and trunk with a garden hose equipped with a high-pressure nozzle and allowing eggs and litter one to two days to dry;
- Raking eggs, litter and debris out from under the tree; and
- Disposing of the eggs in plastic garbage bags. Raking may not be practical if heavy brush, rocks or other material is present under the tree. However, washing the eggs off the tree is still recommended.
"Removal of the eggs from your pinyons will be simplified if you have already treated your vegetation for fire prevention reasons," he said.
"Repeated washings may be necessary since not all eggs will be laid at once." If you wash too late, eggs will have hatched and the young scales (crawlers) will have moved to the needles where they can be treated with insecticides. Egg hatch usually occurs in May, providing a long period of time for egg removal -- but the sooner the better."
Unless there are local water restrictions, consider slow, deep and infrequent watering of your infested pinyons nearest your home, starting as soon as your soils dry out, with a soaker hose placed around the drip line of the tree.
Continue watering until "monsoon" rains are well established.
He also suggested residents refer to the pinyon needle scale publication issued by the Cooperative Extension at: http://cals.arizona.edu/pubs/insects/az1315.pdf and their watering brochure at: http://cals.arizona.
For further information about this insect, or other forest health concerns in the Payson area, contact: Bob Celaya, Forest Health Specialist, Office of the State Forester at (602) 771-1415 or our Payson Field Office at (928) 474-2689.