Can actinovate stunt seedling growth?

[Siberian]

First off, let me say that I use Actinovate regularly, love the product, and recommend it to others all the time. I am not condemning it in any way.

On to the topic at hand. I typically water my seedlings with SeaCom PGR, fish fertilizer, and some EM1 bacteria mixed in and this works quite well. This year, on a few of the seeds that were started later than others, I added in some actinovate into the mix I just described and have been watering the seedlings with it. The seedlings that received this treatment have basically stopped growing and the leaves have become purple (the tops are purple, not the bottoms which could indicate phosphorous deficiency).

My question is, could actinovate have cultivated the young seedlings roots so well that it may be inhibiting nutrient uptake? I should have used the actinovate at reduced rates but did the regular 1tsp/2gallons. Any thoughts?