Fight PSA With Nutrition – Trial 3 Pictures show where the bark has been scraped back to remove the PSA infection. The bark has calloused over in  a few months. I found this quite remarkable.  I have put these photo’s on as I think this product is compatible with what we do. It is targeting the nutrition as we do but from the inside of the plant.  Air8tors have tried to change the sap content to combat the PSA. Yeti seems to do that very well.     Plants treated with Yeti have showed that the bark can callous over where the PSA has been removed, there is still some die back on the canes but the improvement in the leaders was quite remarkable.