Pyru-... This kind of yellowing, on new growth, usually means some immobile nute' is involved, but on a young plant, it's less certain,... initially, I though Fe or S, but the way it's yellowing-- tips/edges in, is backwards from what Fe and S do,... other, lower leaves look Mg defc., and with high demand on new growth in a younger plant like this, even a mobile nute like Mg might not be able to keep up,...lack of spotting/necrosis fits as well,... If the soil pH is 5.8, that's borderline, though not lockout range yet,...feed her more, and get that soil pH up to mid 6's,... and make your fert's fresh, no using hydro' res' leftovers! The pH requirements are very different, as is the whole chemistry,... BTW, what kind of water are you using?.. RO/DI, tap, a mix..?
