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Shirley King | Avenida Primavera

CAL Fire Crew cutting down diseased Torrey Pines.
Photo courtesy Torreyana.
Click on photo to enlarge.

Our revered Torrey pines in the State Reserve are threatened again. The last time this rarest species of pine in the United States was infested with the “confused five-spined engraver beetle” was 1989 - the culmination of two years of drought and the brutal heat in the late summer of 1988.

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From this past December through February 2015 as many as one-hundred (100) Torrey pines that have succumbed to the engraver beetle will be removed by CalFire and inmate crews. Again dry and warm conditions have promoted the rapid multiplication of these native insects and have lowered the Torrey pines resistance - mostly by devouring the tree’s circulatory system, the thin layer between the bark and the hardwood.

A press release from Darren Smith, an environmental scientist with California State Parks reports that the loss represents about two-percent of the current population within the park (about 4580 trees). In 1989 there were 7,000 Torrey pines in the park. Clay Phillips, San Diego District Superintendent states “The infestation of these trees has unfortunately reached a point of no return status, and it is critical we act quickly to avoid infestation to other Torrey pines.”

Torrey pines wage a perpetual battle with the beetle and other pests indigenous to the environment. Having a healthy flow of sap to push out the larvae and to repel the foot soldiers is the sign of strong immunological defenses. At times these trees need the intervention of non-toxic beetle traps that the California State Parks staff have used in the past to control the infestation.

Our landscape Torrey pines in neighboring residential and commercial areas, which are are raised with irrigation do not develop deep roots. When irrigation is reduced or eliminated during a drought, these trees are prone to large beetle infestations that spread quickly to wild or native trees. The telltale signs of beetle activity are small emergence holes, piles of dry boring dust pushed out on the bark surface and eventually the browning tips of stems.

The University of California Integrated Pest Management advises that we pay close attention to our aging, slow-growing Torrey pines, their crowded groupings and the newly planted. Their advice is 1) avoid stress on a tree caused by poor planting methods and timing, injury to roots and trunks, and damage during construction activity; 2) irrigate deeply especially in the summer around the outer canopy, not near the trunk; 3) avoid pruning during the adult beetle’s flight season - February to October; and 4) assess a dying tree with the help of an arborist.

Our State Reserve will repopulate with seedlings and sub-adults. If only we could engineer our weather to support our mature inventory with cooler temperatures and steady, long rains.


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