pinon pitch mass (18687 bytes)

Pinon "pitch mass" borer

By Carl Wilson, Horticulturist, Denver Cooperative Extension

The pinon pitch mass borer is a serious pest of pinon in landscape plantings throughout much of Colorado. Though pinon is the main host, ponderosa and possibly Scots and Austrian pines may occasionally be infested.

Boring larvae gouge the tree's water conducting vessels causing large quantities of pinkish pitch to ooze. Damage can be seen on trunks and large branches. Wounding disfigures and weakens the tree. Heavily infested branches may even break.

Like most borers, pitch mass borer takes advantage of already weakened trees. In landscapes, overirrigation and overcrowding are stresses identified as factors in borer attack. Adjusting irrigation schedules and thinning overcrowded plantings should be considered important parts of any control efforts.

Homeowners can attempt to puncture and kill individual borers with a flexible wire. Note that larvae can be difficult to find as they often tunnel for several inches under the bark. Moth crystals containing paradichlorobenzene (PDB crystals), may be inserted into borer pitch masses to fumigate larvae.

Preventive trunk sprays can reduce attacks. Registered products containing pyrethroids or cygon sprayed to coat trunks and major branches during the June to August flight period of the adult moth help prevent additional boring. Two or more treatments per season should be repeated for at least two years.

Photograph of Pinon Pitch-Mass courtesy of Judy Sedbrook.

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Date last revised: 01/05/2010