Weird bud development

I can't pinpoint the problem... They look "undeveloped". Anyway, here's a pic:



The flowers are in their third week of flowering.
Ebb n flood system; rockwool + clay pebbles; 2x400 HPS; pH between 5,8 and 6,5 (a bit high, I know...); rh 55-65;
Had a minor whiteflies issue but got that sorted out (last week). Could it be a result of whiteflies?

Have you grown this strain before?

Yes I have. It was nothing like that.

I think I figured it out.
Since I'm a newbie, I sprayed my plants with a chemical pesticide. Would that be the cause?