Projects We're Working On: GSOB Confirmed in the Hodges Watershed

GSOB has now been found in Del Dios Park, on Laurel, Kalmia, and Juniper Lanes. It is also on Mount Israel near Detwieler Road. We can assume in the next several years our large Coast Live Oak trees will see GSOB. The adult beetles emerge from mid-May through August, so presence of the beetle in healthy trees may not be detectable yet.

Residents and the City of San Diego are being urged by the Del Dios Habitat Protection League to protect high value oaks from this deadly invasive beetle. We are putting together a community plan to treat trees together to reduce the individual tree cost.

We are asking for people who are interested in being part of the solution to step up and contact Stacy McCline right away.

The gold spotted oak borer is a tiny beetle causing huge damage in Southern California. It infests the region's towering oak species - coast live oak and canyon live oak - and can kill a centuries-old tree in just a year or two.

GSOB Update: May 2017

GSOB Confirmed in Del Dios and Mt. Israel

This beetle - the Gold Spotted Oak Borer, is a highly invasive, non-native flathead borer that kills oak trees.

San Diego County Ag has confirmed the presence of GSOB based on pictures submitted to them on Thursday May 11, 2017. So far, Clark Mahrdt and I have identified the oak killing beetle in two locations on the north end of Del Dios, as well the confirmed location on Mt Israel near Detwieler Road. Additionally, Conor Lenehan, RSF Fire, announced its presence on Mt. Israel at the Elfin Forest/Harmony Grove Town Council meeting last month. According to neighbors, GSOB may have arrived in Mt. Israel a few years ago, but we believe this to be a new problem in Del Dios, based on my examination the trunks of failing and dead oak trees for the last 3 years.

Please review the GSOB Identification Guide, especially page 5. When you first start looking at the trunk of a mature oak tree you will notice there are a lot of different shapes and sizes of holes in it. GSOB has a characteristic D-shaped hole in the bark, about the size of the lead of a #2 pencil. 

GSOB D Shaped Hole in Oak Zoom.jpg

Evidence of GSOB

GSOB has a characteristic D-shaped hole in the bark, about the size of the lead of a #2 pencil.

The first steps for limiting the spread of this infestation are 1: Alert the community that no oak wood should be moved in or out of our area and 2: Determine the extent of the problem – how many trees are effected and how they are grouped. According to the resources below, activities to contain the extent of the damage by GSOB include removing dead and dying trees effected with the beetle and using preventative treatment of unaffected or slightly affected trees in the vicinity.

We will need to work together and coordinate our efforts to be effective in stopping the spread of this pest in our area.

I will post again as I have more information to share.

Stacy McCline


Del Dios Habitat Protection League



Additional links, resources and video can be found in our original GSOB post.

Mysterious Willow Die-Off at Escondido Creek

A mysterious pest has damaged willows along the Escondido Creek Watershed, leaving conservation officials scrambling for answers to the die-off.

Officials with the Escondido Creek Conservancy originally feared the damage was caused by the shot hole borer beetle, which attacks 137 tree species including willows, oaks and sycamores.

Tests at UC Riverside came back negative for a fungus associated with the beetle, but didn’t reveal what could be threatening the watershed.

“.. It was found to not be the beetle — it was something else going on,” said Ann Van Leer, executive director of the conservancy.

The problem began over the summer, when the Escondido Creek Conservancy learned that trees in Elfin Forest were rapidly wilting and dying, Van Leer said. Months later, the damage is especially visible near Questhaven and Harmony Grove Road — a spot that conservancy board member Leonard Wittwer called “ground zero”of the infestation — where a tangled heap of branches lies in the creek bed. Blackened leaves droop from nearby trees.

“When these things became infested, it was like someone turned their blow torch on and burned them,” Wittwer said.

On Aug. 3, the conservancy closed the trails in the Los Cielos Preserve, out of fear that the invasive beetles could be causing the destruction.

The Kuroshio Shot Hole Borer has infested areas of coastal San Diego, according to the University of California Division of Agriculture and Natural Resources. The insect, an invasive species that originates from the highlands of Taiwan and Okinawa, decimated the Tijuana River Valley, where hundreds of thousands of denuded tree trunks stand in the place of formerly lush streamside habitat.

The collapse of willow groves ripples through the watershed’s ecosystem, Van Leer said.

“Willows are one of the key trees which support other plants and animals,” she said. “It’s one of the foundation plants. A lot of birds and insects rely on the willows. It’s an indicator species of the watershed.”

The loss of those trees harms animals such as the least Bell’s vireo, an endangered songbird that lives along streams. And the stands of dead wood pose their own hazards to surrounding communities.

“It’s an ecological bummer and then becomes a fire hazard,” Wittwer said.

Worried that Escondido Creek could suffer similar damage, the conservancy closed its trails to the public on Aug. 3, and submitted samples from the trees to plant pathologist Akif Eskalen at UC Riverside.

“We didn’t know, and we wanted to be very cautious, because we didn’t want people and bicycles spreading the infection by moving through the area,” Van Leer said. 

They were surprised but relieved to find that the samples showed no signs of Fusarium fungus, which transports and spreads the beetle infestation. Instead, the lab found a different fungus, Phaeoacremonium.

The results only compounded the puzzle, however, since Phaeoacremonium is a slow-growing pest that isn’t associated with sudden die-offs.

“In communications with Dr. Eskalen, he was interested as to why our willows trees have died so quickly from this particular fungus, which is known to slowly kill trees,” the conservancy stated on its website. “He wondered if something else may additionally be affecting these willows.”

Eskalen said he plans to visit the site on December 2, and hopes to get additional clues to the die-off.

"This is a new disease that we haven’t figured out yet," he said. "We still don’t know what caused the decline of those willows."

After learning that the trees tested negative for the invasive beetles, the conservancy reopened the trails at Los Cielos. They’re also looking for ways to help boost the trees’ resistance to the fungus, and plan to watch carefully for signs of renewed die-off next spring. In the meantime, officials urge hikers and cyclists to stay on the trails, keep dogs on leash, and never remove firewood from the preserve.

View images, video and full article

Reporter: Deborah Brennan

Photographer: Peggy Peattie

Editor: Misael Virgen

December Work Parties

Planting Has Commenced!

With the help of our volunteers, this month the DDHPL has planted hundreds of new natives. Rather than digging holes for each new plant, the recent rains have made the ground pliable enough to pound in each pole cutting with a 3 pound sledge hammer. 

Dec. 3-4: "Thanks to the efforts of local volunteers and our friends from Solana Beach Eco-Rotarians, the Del Dios Habitat Protection League's efforts to restore our native environment was bolstered by the planting of 250 natives!"  
- Stan Alstrum

Dec. 10-11: 200 Pole cuttings of mulefat were planted at Green Lagoon on Saturday and more poles collected on Sunday for planting the following week.

Dec. 18th: A group of our local teen volunteers hammered in 300 plants - bringing the total for this group to 750! Go Teens!!

The "Mulefat Chain Gang" earned their name by planting 300 pole cuttings in a single day!

The "Mulefat Chain Gang" earned their name by planting 300 pole cuttings in a single day!