Here is a quote from the research article I cited in this thread, that shows a potential detrimental effect of foliar-applied animal-derived PHs:

In addition to the<br role=”presentation”>positive effects of PH-treated plants, there are several authors<br role=”presentation”>(Ruiz et al., 2000; Cerdán et al., 2009; Lisiecka et al., 2011)<br role=”presentation”>reporting phytotoxicity effects as well as suppression of growth<br role=”presentation”>related to the use of animal-derived PHs of fruiting crops. This<br role=”presentation”>phenomenon is known as ‘general amino acid inhibition’ (Bonner<br role=”presentation”>and Jensen, 1997) and it is due to excessive leaf uptake of free-<br role=”presentation”>amino acids, which causes intracellular amino acid imbalance,<br role=”presentation”>energy drain due to active transport of amino acids, inhibition<br role=”presentation”>of nitrate uptake, and increase of cell susceptibility to apoptosis.