| Abstrakt: |
The efficacy of ammonium thiosulphate as a blossom thinner of ?Delicious? apple, ?Winter Cole? pear and ?Hunter? apricot in southern Tasmania was assessed. Ammonium thiosulphate at concentrations of 0.3, 1.5 and 4% (v/v) was applied to both ?Delicious? apple and ?Winter Cole? pear trees at 20% bloom, 50% bloom or full bloom. At 4%, ammonium thiosulphate proved to be phytotoxic to both crops, resulting in the severe burning of foliage and flowers and also bud death. At 1.5%, ammonium thiosulphate reduced the crop load to an acceptable level without excessive damage. The 0.3% concentration was ineffective regardless of time of application in ?Delicious? and at 20% bloom in ?Winter Cole?. Russet incidence was increased on ?Delicious? by the highest concentration applied at 20% bloom. Shoot number increased in some treatments, however there was no effect on return bloom. When ammonium thiosulphate at 2.0% was applied to ?Hunter? apricot at 20, 40, 60, 80 or 100% bloom, fruit set was reduced regardless of time of application. Ammonium thiosulphate also improved return bloom of ?Hunter? apricot. |
