If you can identify the entry point (fine sawdust like material on the trunk) simply take a sewing needle and probe in several spots all the way throught the trunk to effectively spear the borer. It may slightly stress the plant if you go a little bit overboard but is much less than the damage the borer creates. On my outdoor grows, I apply a insecticide called Imidacloprid (patented under the trade name "Merit") as it is a systemic, broad-spectrum insecticde that works well as a preventive for boring insects. If the damage is confined to the stems only (not the trunk) you can also cut the damage away with a pair of pruning shears then dispose of properly. I usually burn them as I hate the bastards. Other insecticdes such as Acephate (Orthene) can be applied early in the season in your immediate grow area for control of beetle borers.
I use Merit alot @ work for turf applications, I wouldnt smoke anything treated by it imo, its nasty stuff, but if applied EARLY in the season to your garden area, like, before anything is planted/sprouted, can prevent grubs/beetle worms/larvae at bay. Be wary tho, Merit is a pretty broad spectrum insecticide, so theres LOTS of beneficial insects you could possibly be impacting as well, lady bugs, hornets/wasps/bees, ect. Make sure you are properly liscenced to apply the product and fully understand the risks
gl.
*edit*
that msds is pretty crappy lol, youd probably get some better information regarding application to agricultural crops/edible foods on the label.
@ Spanishfly. typically, if the bottle says dont ingest it, then even in a super deluted amount, you shouldnt ingest it