Silicon is directly related, in my experience, to microbiological activity. I believe that is John Kempf’s measure as well. Once we got that going, with the soil primer, less chem inputs, and ending tillage, our numbers have gone up. We never saw a bump applying silicon as a foliar (on stone fruits), but there are a number of products available, especially in the organic fertilizer space. I have cherry new branches (this year growth) that are usually easy to bend and break with a tenacity much more like a piece of plastic. Check your sap tests, that is where you will see it. We do have sandy soils, so that may be part of things for us.