There has been some talk about the use of promalin to help overcome the damaging effects of freezing temperatures. Only a small amount of research has been conducted on this. Dr. Steve McArtney showed that Promalin applied after damaging freeze events could increase parthenocarpic (seedless) fruit development, but not every time. Keep in mind this was only shown to be effective for freezes during full bloom. In Dr. McArtney’s research, Promalin did increase fruit set, but only to about 25% of a full crop. In similar work in Michigan, Promalin applications (1 pint/acre) were not effective in increasing apple fruit set.
Based on this research, it’s clear Promalin is not a silver bullet, but MAY help a little in some cases. Don’t expect this to work in all cases, but if you’re lucky you may get some slight benefit.