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UC Nursery and Floriculture Alliance

From the UC Blogosphere...

The Monarch and the Mantis

A gravid praying mantis, her abdomen bloated, grabs a migrating monarch nectaring on a butterfly bush. (Photo by Kathy Keatley Garvey)

If you're rearing monarchs or offering them a “way station” of nectar-producing flowers in your yard, there's...

Posted on Wednesday, October 26, 2016 at 5:00 PM

Sometimes The Unexpected Happens

UC Davis entomology student Wade Spencer holds the female praying mantis. (Photo by Kathy Keatley Garvey)

Sometimes the unexpected happens. Take the case of the female praying mantis delivered to the Bohart Museum of Entomology,...

Posted on Tuesday, October 25, 2016 at 5:00 PM

UCCE scientist finds South American palm weevil in California

Southern California's iconic palm trees are now threatened by another invasive species, the South American palm weevil, reported Mark Muckenfuss in the Riverside Press Enterprise.

Mark Hoddle, UC Cooperative Extension specialist based at UC Riverside, has been monitoring the pest south of the border and recently visited Tijuana to assess the infestation.

Dead palm tree infected by South American palm weevil. (Photo: Mark Hoddle)

"We found about 130 dead Canary Island palms," Hoddle said. "It's been devastating in Tijuana."

On the way back to Riverside, he stopped in Chula Vista, where he noticed dead palm trees.

“I thought, ‘What the heck?' and yeah, it was there, too,” he said. “It was basically an accidental discovery.”

Hoddle recently reported in California Agriculture journal on the successful eradication of a different invasive beetle attacking palm trees in Laguna Beach, the red palm weevil. The cost of the eradication was more than $1 million.

In the Press Enterprise article it said the South American palm weevil is susceptible to insecticides and pheromone traps. If the beetle's presence in a palm is determined quickly, the tree can be saved.

South American palm weevil has recently spread to San Diego County. (Photo: Mike Lewis)

Hoddle said he is concerned about the scope of the South American palm weevil infestation in Southern California.

"My personal feeling is we might be on the verge of a crisis now," Hoddle said in a press release issued by UC Riverside. "The big problem is we don't know how far the weevil has spread. We really need help from the public in tracking its spread."

Hoddle and other experts will speak at a symposium tomorrow about the weevil at Sweetwater Regional County Park in Bonita, Calif.

Posted on Tuesday, October 25, 2016 at 8:49 AM

Marek Borowiec Drawn to Ants, Especially Army Ants

This is Lioponera princeps, one of the ants that Marek Borowiec studies. (Image by Marek Borowiec)

Marek Borowiec's world revolves around myrmecology, the scientific study of ants. Borowiec, who received his doctorate in...

Posted on Monday, October 24, 2016 at 12:35 PM

Using Eucalyptus Leaves for Mulch or Compost

Help for the Home Gardener from the Help Desk of the
UC Master Gardener Program of Contra Costa County 

Client Request: I have several eucalyptus trees on my property. They shed a lot of leaves. I'd like to use the leaves for mulch and possibly compost, but when I research these uses, I get confusing and/or contrary guidance. My request: Can I use eucalyptus leaves/cuttings as mulch and/or compost in the home garden?

Help Desk Response:  We understand your frustration with the information you're finding on the use of eucalyptus leaves as mulch. In doing the research on your question, I too, found a lot of conflicting information. The Master Gardener Program is under the umbrella of the University of California so the information that follows is all based upon scientific research.

Eucalyptus Toxicity
While it is true that eucalyptus leaves do have some toxicity, the research shows that well composted eucalyptus leaves pose no problem when used as a mulch or when mixed at appropriate quantities into a growing medium. The research also concluded that fresh eucalyptus leaves were shown to be a good weed suppressant when applied to a depth of 4 inches (10cm).
Following are two articles by James Downer & Ben Faber on the subject of eucalyptus mulch and eucalyptus compost.  

The University of California research concluded that, when handled properly, eucalyptus is safe for use in compost (i.e., incorporated into the growing medium). The toxicity of the eucalyptus are rendered harmless by the composting process, especially if you are working a hot compost pile. (See http://vric.ucdavis.edu/pdf/compost_rapidcompost.pdf)

When composting eucalyptus, the leaves are considered green plant material and will constitute the nitrogen part of the composting process. To effectively use eucalyptus clippings or leaves, you will want to mix them thoroughly with carbon-based materials such as newspaper, cardboard or other dry leaves or plant material. 

The University researchers suggest, if you still have concerns, that you consider composting eucalyptus in a separate hot compost pile, keeping the pile well moistened and turning it often to keep the mix hot over a longer period of time.

Once the eucalyptus is well composted you can do a germination test to test for toxicity by using the compost as a medium to start 10-12 fast growing seeds such as radishes. If a majority of the seeds germinate, the eucalyptus toxicity can be considered neutralized by the composting process.

If you want to use fresh eucalyptus leaves in your landscape, the conclusion suggests to favor using them on the woody landscape plants in the home garden setting.

I hope this gives you the information you were looking for and sets your mind at ease.

Help Desk of the UC Master Gardener Program of Contra Costa County (BHD)

Note: The  UC Master Gardeners Program of Contra Costa's Help Desk is available year-round to answer your gardening questions.  Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA  94523. We can also be reached via telephone:  (925) 646-6586, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/ MGCC Blogs can be found at http://ccmg.ucanr.edu/HortCoCo/ You can also subscribe to the Blog  (http://ucanr.edu/blogs/CCMGBlog/). 


Posted on Monday, October 24, 2016 at 12:06 AM

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