Is this some kind of borer? The white feels like sawdust when touched.
What do I do?
Katy
Ambrosia beetle, most likely
I’m just reading that now. What would you do? It suggested permethrin to the bark of the other trees and leave that one as a trap tree. So that tree is toast!
Thanks guys.
Sources say that you may want to leave this tree as a “trap” tree until after peak emergence of the beetle then burn or chip it. 
This tree is on its own roots and this is at the base. Any suggestions about saving this growth? I think it would not be contaminated. I’m not sure how much root system it has or how best to save that root system. Supposedly I should wait 3-4 weeks before destroying the contaminated parts of the tree. Right now two of the main three trunks of the tree are affected. What would you guys do if it were your tree. (I might add that this is one of my least favorite trees but I definitely want to protect my others.)
The same thing happened to my mulberry and fig tree (all about 6’ tall) that I had just planted, all 3 died so I pulled them out of the ground and put them back in the containers and now I have new growth coming up from the ground. Figured I would cut the dead trees out and see if the young ones will live (Not sure if they attach the roots, don’t think so), someone told me the trees must have been stressed because the beetles only attach weak trees (just planted mine and had frost)? I sprayed mine with pyrethrin bug spray and it seem to have stopped any more from attacking, the spray doesn’t seem to have harmed the other trees that I sprayed so I will have some on hand next year.
I hope both of y’all’s trees make it! I don’t know what I would do with a mulberry or other tree I don’t know how to root. But I just had this happen to my big fig tree that dies back every year, and I’m hoping to use the new growth from the roots to make separate, new trees. Then I’ll get every bit of old wood out of there.
I already cut off everything I could with big loppers. And I treated it with insecticide. Doesn’t help for the ones in the wood already (I think I’ll carpenter-glue the pinholes).
I didn’t even know we had this insect here! I’ve never seen it. My fig dies back each year, but it’s old enough now to have fat branches that get injured by the cold. That must be what attracted them! They like a certain diameter wood.
I also read that ethanol (if I recall) is a scent the injured wood puts out that attracts them, so I don’t know if painting branches, etc would help. ??
I’m definitely painting and spraying my other trees while these awful bugs are in my yard 
Peaches are supposed to be wood they often go for, and of course figs or mulberries. Persimmons, too!
They drilled holes into perfectly healthy wood on mine, btw. More holes were on the frost-damaged branches, but then they also moved to the healthy base. They are tiny and numerous (and fast workers, apparently).
Next year I’m pruning out any frost-damaged larger wood on figs ASAP after bad frost risk is over. I think it attracts them.