Now before we jump to any conclusions, this is a correlation, and not proof of causation. But, it’s certainly an encouraging sign. Maintaining a health biome on plant leaves helps maintain system productivity.
Interesting. Just discussed this issue with a horticulturist today. She stated that leaf bacteria is as important as in the rhizosphere. the key is the ratios or balance between them and, of course, the type of bacteria.
That said, from the perspective of the soil and other environmental conditions being the determinant factor whether, and to what extent, healthy or other bacteria develops, (paraphrasing Florence Nightengale: “There is no bad bacteria, only bad soil and conditions!”); what would be the best balance and how family/genera/species dependent is that?