Leaves falling off in flowering

[Abdultj]

Hey guys, I just switched to flowering 4 days ago, now healthy green leaves are falling off from below, some are rusty, any info?
Upper part of the plant is doing fine
Am growing in coco/perlite, Mars hydro ts

1000 and feeding flora trio series

 

[Jimster]

Yellowing of the leaves is common during later flowering. If you are seeing yellowing of the bottom fan leaves, you could probably use a dose of Nitrogen, although it doesn't really look like a Nitrogen issue to me. Plants grow differently and use nutrients in different amounts between flowering and vegging. Have you checked any Ph or PPM/EC levels? That would be my first thing to check, otherwise you are guessing... which can make things a lot worse if you aren't sure of the cause.
Things look pretty good overall. As long as the new growth is doing well, I wouldn't worry too much, but it should be investigated to avoid recurring problems in later grows.

 

[Abdultj]

Green leaves are falling off

 

[Anthem]

How often are you watering the plant and how much water are you giving it? What size is the pot?

 

[Formallyhap]

what's your soil?

Looks like PH issues to me