Problems persist with Rancho Santa Fe eucalyptus trees

RANCHO SANTA FE — The red gum eucalyptus trees in the Covenant are once again under attack by the pesky and persistent red gum lerp psyllid. The small insect sucks sap from the eucalyptus leaves, which can damage and, in many cases, kill the tree. The problem began in the 1980s, became a large problem in 2001, and returned again last year.
Natural predators, wasps from Australia, were bred in a controlled environment and then introduced into the Covenant to remedy the problem. The wasps kill the parasite by boring into the white cone and laying their eggs inside, thus killing the lerp psyllid. It was hoped the wasp could control the problem, but it appears the red gum lerp psyllid is ultimately winning the battle.
The Rancho Santa Fe Association board of directors asked expert David Shaw, a farm adviser with the University of California Cooperative Extension, to study the problem and advise accordingly. Working with Timothy Paine from the University of California Riverside, Shaw studied the problem and gave his report at the July 2 Association meeting.
“Other insects are part of the infestation,” Shaw said, identifying part of the problem. “There is now a barrage of insects.” Besides the red gum lerp psyllid, there are beetles scalloping the leaves of the eucalyptus trees. Other hyper parasitoid insects are also doing damage.
Shaw said there are many remedies, but all require trees to be monitored.
“We need to look at these trees one by one,” he said.
That is a daunting task with the large number of eucalyptus trees in the Covenant.
Besides insect infestation, another part of the problem is that the eucalyptus trees, which were planted nearly 100 years ago by the Santa Fe Land Improvement Company, are now at the end of their natural life cycle.
“We need to replace trees,” Shaw said. “There are not enough trees being planted to replace the dead ones being removed.”
This prompted responses from Ranch residents attending the meeting, including longtime Association member Ann Sensibaugh.
“I’ve lived here for the past 100 years,” she said jokingly. “And it’s time for a plan for rebeautification.” Sensibaugh said she felt strongly that it is a community problem for all of Rancho Santa Fe.
Ranch resident and school board president Carlie Headapohl voiced her concerns, too, for she and other Covenant members have received letters from the Fire Department telling them to remove dead trees within the next 30 days. “How can we tell for sure if they’re dead?” she asked. “And it’s expensive to remove them. It’s a difficult situation.”
“Eucalyptus trees are dead if the trees have lost all their leaves and the bark shrinks,” Shaw said. Otherwise, the trees should be pruned and cleaned. “We need to redirect the growth,” he said.
Paul Flores, an arborist who has worked in Rancho Santa Fe for many years, monitors many trees for Ranch clients. “We’re having some success with injections and deep irrigation,” he said. “But I recommend replanting and diversifying.” Flores and Shaw recommended replanting, using eucalyptus that is resistant to lerp psyllid infestations.
The Association will continue to monitor the trees and seek solutions to this difficult problem. “The trees are an important part of our history and lifestyle here, so we need to stay on top of this,” President Bill Beckman said.

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