Of all the plants in our yard the one I care most about is our avocado tree. I’d be despondent if anything happened to it. Which is why I panicked when I first heard about the Polyphagous Shot Hole Borer (PSHB), a beetle that spreads a fungus Fusarium euwallacea. First noticed in 2003 here in Southern California, the PSHB seems to damage some trees more than others.
Concerned about losing my avocado tree I wrote Akif Eskalen, a plant pathologist at the University of California, Riverside. Dr/ Eskalen’s lab has done a lot of work on the PSHB and what to do about it. I asked him specifically about avocados and here’s what he had to say in an email,
My lab has been conducting a continuous survey on PSHB on infested and non-infested avocados in California since 2012. Based on the preliminary results from our survey the beetle PSHB seems to be attacking and causing damages on primary and secondary branches of avocado only. We have also seen attacks on the trunk of the trees but somehow the beetle is not successful establishing galleries there which could cause of quick death of the tree. I believe with a proper orchard sanitation you can reduce the damage of the beetle and also keep the beetle population down in the orchard . . . we are still continuing experiments with different insecticide and fungicides on avocado against this beetle and their fungi. An insecticide (Hero) has already registered under Section 18 that could be used by growers in CA.
He provided a link to a short publication his lab put out on orchard sanitation best practices as well as a link to information for avocado growers on the use of Hero. Hero is a pyrethroid-based pesticide.
For my own backyard tree I’m going to:
- Make sure pruning tools are disinfected before use. This is one of the main reasons we use a qualified arborist.
- Avoid moving firewood around. I’m going to have to think carefully about the wood I import for my pizza oven.
- Use mulch that has been chipped to less than 1 inch.
I’d sure hate to lose a tree that provides six months worth of free and delicious Fuerte avocados.