Hello aspirant.

To appear class 12 (PU 2 ) supplementary exam of Karnataka board which will be conducted in the month of JUNE you need to fill application within 29 April 2019 (Some colleges end the date early , once you confirm with your college) as last date to pay fess of all the students to pu board by  colleges is 30 April 2019 .

Supplementary exams will be conducted from 7 June 2019 to 18 June 2019.

For more information refer 

pue.kar.nic.in

or 

http://pue.kar.nic.in/PUE/PDF_files/exam/2019/circ_March_2019.pdf

All the best.