I picked and froze blackberries from a neighbor's plants, and when I had
enough (about 3kg) I prepared my must for the primary. After crushing
the fruit I added the usual things, including 1.5 tsp of yeast nutrient
in the form of food-grade urea. I also sulfited with two Campden tablets
primary must, which by this time was nearly 2 gallons. This sat for 24
hours.

I then pitched the yeast, Lalvin RC212 (Bourgovin), per their
directions, which involved dissolving some of the yeast in warm water
and letting sit for 15 minutes before adding it to the must. I noticed
at the time that the yeast solution smelled a little off-putting.

Within 24 hours of pitching, my must acquired a thick bouquet of
hydrogen sulfide, and 5 days later it's still as bad.

This happened last year when I made wine from the same plant's berries.,
but then I'd used Red Star's Premier Cuvee. I eventually drove out the
H2S with agitation, but it made me wonder what went wrong. This time I
was very attentive to sanitation, and I'm rather disappointed that the
H2S presence has recurred with such vigor.

After doing some internet searches, I get the impression diammonium
phosphate might have been a better nutrient. Does anybody have other
suggestions? There's still plenty of berries to pick this season, and I
might be able to re-try a batch this season.

Marshall