true leaves shriveling and falling

[dice]

It can be phosphorus deficiency, and it can also be a reaction
to cool temperatures (still phosphorus deficiency, but it has to
do with the phosphorus uptake mechanism rather than the
actual available phosphorus in the soil). If already dealing with
small root balls from being a little too wet, it may be better to
spray the foliage with a mild water-soluble fertilizer high in
phosphorus than to water it in. Phosphorus deficiency is
generally most visible on the bottoms of the leaves.

It can also be a disease symptom, but it is kind of early in the
season for those (mostly spread by insects that are not active
yet in cool climates).