Response is temperature dependent, and the greatest reduction in berry set occurs when temperatures are in the 90's. In young, vigorous vineyards, excessive shatter can occur when warm temperatures and a rapid bloom occur and lower rates should be used. Bloom sprays to Flame Seedless increase berry weight but have little effect on berry shape. Ideally, application should be applied at 40 to 80 percent bloom. Effectiveness drops rather rapidly if sprays are applied much earlier or later than the optimal stage.
Shot berries are more likely to occur when sprays are applied early in bloom or before bloom.
Completion of bloom to berry set. Applying gibberellin to Thompson Seedless during this period between bloom and berry set increases berry size and elongates the berry. However, Flame Seedless does not respond to gibberellin applied at this time - there is no increase in berry size or change in berry shape. Berry set and growth. This is a long response period compared to Thompson Seedless or Perlette.