Armothin is a surfactant manufactured by the Azco-Nobel Co Ltd, which has showed useful activity as a blossom thinner on stone fruits. It is a 98% fatty amine polymer.
- In trials at East Malling, high volume sprays (1000 l/ha) of Armothin at 0.5% active ingredient were tested at three timings, balloon blossom, 5 days after full bloom on the two-year-old spurs or 10 days after full bloom (Webster and Spencer, 2000).
- The trees used for the test were eight-year-old Royal Gala on M.9 rootstock.
- Concern was expressed by the chemical manufacturers about possible fruit russeting.
- To counteract this a programme of Regulex (GA4+7) was applied to some of the Armothin treated trees.
A second trial on Royal Gala also included sprays of Armothin, applied 10 days after full bloom. The results of the two trials were inconsistent.
- In one trial no significant thinning was achieved, whilst in the other, mean fruit size and grade out was improved in comparison with unsprayed controls.
- No significant phytotoxic damage was recorded, irrespective of whether the treatments were supplemented by Regulex sprays or not.
A third trial conducted on the variety Jonagold was also disappointing with only minimal thinning following the Armothin sprays.
On this limited preliminary evidence, Armothin appears to hold only minimal promise as a potential blossom thinner for apples under UK conditions.
- ‘Armothin’ has proved an effective thinner for stone fruits in Italian trials.
- In UK trials on apples it gave inconsistent results as a flower thinner.
- ‘Armothin’ is not approved currently for use as a flower thinner in UK orchards.