Its confused by the darkness, the lack of airflow, the massively changed environment in that covered area of the branch, it provokes a response, a hormonal one that triggers the nanners. Like I suggest - try it with the light deprivation (black plastic) and no silver or other metals and see how you go. I reckon you'll get the same occasional elusive results.
And do it indoors - not outdoors, #1 maybe its different where you are but here we don't want our pollen floating around to other nearby growers and #2 you can better control for environment.
And do it indoors - not outdoors, #1 maybe its different where you are but here we don't want our pollen floating around to other nearby growers and #2 you can better control for environment.