Project Update

Fall and Winter League Activities

The Habitat Protection League will be working on 3 volunteer projects for the 2018/19 wet season.

·         Re-generating Oak Woodland where dead Oaks have been removed.

·         Planting cactus to create Cactus Wren habitat where cactus patches were destroyed in 2007

·         Reclaiming Riparian function through planting natives to populate areas that once supported eucalyptus.

Please check our Events Page for opportunities - Hope you can join us!


Oak Woodland

More than a dozen trees dead or down trees were removed in August, funded and supported by City of San Diego Public Utilities Department working with the DDHPL. The trees were mostly dead from a combination of stressors including drought, fire damage, fungus or Western Oak Bark Beetle. However, two trees in Del Dios Park were killed due to intense GSOB activity.

The areas where the dead oaks were removed present a timely opportunity to plant new oaks. We will prep the ground, plant seedlings and nurture existing small oaks.

Rodent activity in these planting areas is a big problem for acorns and seedlings. It can be reduced when the areas around the small oaks are clear of grass or low plants where rodents can hide. Research shows that a 4’ circle around the plant is a big help. We will mulch the areas to help with moisture retention, weed suppression and to keep the critter pressure low. Gophers… are the most difficult to protect against. We will be planting a few of our sites with wire cages.

We will be having a work parties to prepare areas for the acorn planting. We will be working primarily along the Coast to Crest Trail where the city has removed dead oaks.

Cactus Scrub

The San Dieguito River Park has done some great work planting large cactus fields to provide needed habitat for our declining Cactus Wren population. Our volunteer efforts, in cooperation with the SDRP, can augment their work with smaller patches where the existing cactus was damaged by wildfire and could benefit larger groupings.

Recommended: Tongs for planting!

Recommended: Tongs for planting!

Riparian/Sage Scrub

Activities will include planting potted plants, spreading mulch, and removal of euc debris. This mainstay of our efforts since inception, but is mostly in a maintenance phase this season.


Please check our Events Page for more volunteer and event info.

Got Acorns? We’d love to plant some!

This October we are asking for help in gathering a genetically diverse collection of acorns. You can help by picking 5-10 rich brown, plump, dense acorns from each your favorite trees.  The acorns appear to be ready in the next few weeks for collection. Donations can be left on top of the mailbox for 20216 Ash. They will be stored properly for planting.

Studies have shown the best germination success for acorns comes from those that are removed from the tree before falling and don’t dry out before they get planted. We are looking for all our local species of oak. If you collect Engelmann and Scrub Oak, please put them in separately labeled bags.

Sadly, last year’s attempt at starting oaks from our local acorns was a miserable failure. None of our oak seedlings made it. Mice and squirrels dug up the planted sprouted seedlings and the rest dried up in the very hot months of June.

Its documented that predation from rodents is commonly the highest cause of mortality for young oaks and acorns. This can be reduced when the area around the planting is cleared of the cover where mice and their cousins like to hide. We will have oak planting work parties along the Coast to Crest Trail where the city has removed dead oaks.

This year we will start planting before January to give the seedlings more time to establish. In the spring, I am hopeful we can recruit local volunteers who can offer supplemental water to our little oaks on their regular walks.

Looking forward, we have a new crop of acorns and planting opportunities.  Thanks in advance for your acorn donations.


GSOB Map - March 2018

The following map images show oak tree evaluation results through March, 2018.

You may also download a pdf image of the full map.


Each dot represents an oak tree. Color legend:

Red = GSOB confirmed, High Risk

Orange = GSOB confirmed, Lower Risk

Green = Healthy

Yellow = Problem Tree, no GSOB

Purple w/ Black Outline = Removal Candidate

Click images to enlarge.




GSOB Update: March 2018

GSOB Update

As most of you know GSOB is in its early stages in Del Dios and is already virulent in the Mt Israel valley. In Spring 2017 Brett Hutchinson meet with 40 residents in Mt Israel to show us bugs, canopy assessment, D shaped exit holes and a whole road show. The week before the Habitat Protection League hosted 85 people at a firehouse meeting with Dr. Tom Scott, UC Riverside, and Kevin Turner of Cal Fire.

Winter 2018: Most of our Oaks are suffering from drought stress from our hot summer and late rains. Oaks are tough and can handle many stressors that mother nature dishes out. What makes it hard are the extra things that humans add to the mix: grading, hardscapes, watering or planting schemes that may suit fungus more than oak tree roots, and non-native insects. Most stressor are slow acting. However, GSOB weakens the vascular system of these massive, life supporting living organisms and can kill a tree in a couple years.

You may see either Rob or Stacy McCline (and more volunteers - come help us!) poking around Del Dios collecting data about our oak trees. This accurate, eyes on the tree on data is one of the Best Management Practices used to treat GSOB conservatively and effectively. Our GSOB treatment plan focuses on spraying the trunk and thick branches of the oaks before adult beetles emerge. We are scheduling treatment in mid April.

A meeting with Plant Care Specialist, Ricardo Agular, is scheduled for March  21st at 6 PM in Del Dios Park. You'll have the opportunity to ask questions, learn about the signs of infestation and who to contact to have your trees effectively treated. Sign up for our newsletter or follow us on Facebook for updates to the meeting schedule. 


Bring a Sample

We recommend bringing a sample of the bark or leaves from oak trees on your property that you think might be infested. Photos are also acceptable.
Can't attend the meeting? Email your photos and comments to Susan at

GSOB Facts

• Crown thinning, not dead branches, suggests GSOB infestation.

• An attacked oak won’t last long once it looks bad. Big trees usually die quickly.

• An oak can withstand GSOB attack for 1-15 years before dying. Factors include: health, drought, size, rot and level of insect attack. 

• GSOB is spreading.
– By movement of infected firewood.
– Dispersal of beetles primarily within an oak canopy.

• There is no cure for GSOB.
– No biological control is being attempted. The natural predator is a parasitic wasp, but UCRiverside couldn’t get it to breed.
– Not an Agricultural threat so not much funding is available to study the pest.

• No existing template available for addressing conservation lands or ecologically significant woodlands. Best management practices are applied for each situation.

• Cal Fire grants are available to remove trees, not to save them.

One of our local residents, Diana Short, had her trees treated last year. Here's what she had to say about her experience. 

"I have enjoyed learning about this beetle this year. It is not my favorite insect, for sure. To protect the oaks on "my" property we had a professional team visit and they gave us a topical spraying recommendation based on the size, age, and species of oaks. The cost was less than I had anticipated because I counted all the oaks, even the very young (less than 12" diameter), which are less at risk, apparently and didn't need treatment. Of the four trees sprayed, there is only one that is not doing so hot. Before spraying we identified the little black "D" s on the trunk and saw that it was not as verdant as others. It might make it- we hope for the best. This season I will be spraying early to hopefully thwart further damage. I am no expert, but when I'm out walking in the neighborhood I try to observe the general health of the local oaks. Most look good. I hope our oaks outlive this unwelcome beetle, and that this small act of tree care saves their lives."

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