Fan leaves hold nutrients in it for the plant so if the plants not getting the nutrients it needs the fan leaves start letting off the nutrients it's storing to help the plant get the nuts and the fan leaves discolor and die off starting from the bottom up
I use alittle kelp and super thrive Nd soak a napkin with that Nd then put the seeds in the napkin then in a baggie ever since I started doing that my germination ratio boosted up so much even on seeds I had for 4 years did 50 of them and 46 sprouted that just my technique tho !!