Blackcurrants: Evaluation of dormancy breaking treatments & Field evaluation of Erger G for dormancy breaking (Combined project with GSK213)

This work has identified potential alternative treatments for dormancy breaking in blackcurrant and has quantified the effects in a year when natural winter chill levels were lower than normal. Two adjuvants, Activator 90 and Silwett-L77, showed potential as alternatives to Erger G when applied with calcium nitrate as dormancy breaking treatments on Ben Tirran blackcurrant with a winter chill deficit of just under 1000 hours <7C. However, the field observations on Erger G showed that it cannot be assumed that: (a) treatments showing potential from bud stick tests will perform as well in the field (b) that the initial forcing of bud break will necessarily result in a more even crop.

A number of commercial blackcurrant cultivars are known to have a significant winter chill requirement to enable even bud break and uniform ripening.  With the prospect of warmer winters, this chill requirement may be increasingly difficult to achieve. A range of treatments were analysed on cut bud sticks of dormant Ben Tirran that had not received sufficient winter chilling for normal bud development.