New growths turning brown and withering from the bottom up

[malteseproverb]

I haven't been fertilizing with as much dedication as I used to, but ordinarily I'd use rain water with Ray's K Lite and a kelp supplement in the spring/summer. A couple of the affected plants have had that regimen continue, and others I'm just using tap, and I use tap most of the time in the winter with no fert.