Maybe I'm a bit slow here...but how are ddays and hitlist related? I've still got 1 dday of my initial 5 ddays, so may be i'm not getting the difference..
With ddays you get to use your hitlist, without them you can't use the hitlist, with ddays you get 10 fertilizer every 10 minutes when you have no ddays you only get 5 fertilizer every 10 minutes.