Both products - which contain 6-benzyladenine and can increase fruit size and encourage return bloom the following season - have had full approval for use in mainland Europe for several seasons now.
However, this option was not available to UK growers until last season when the Horticulture Development Company (HDC) applied to the Chemicals Regulation Directorate for an emergency approval.
HDC technical manager Vivian Powell has since worked with the suppliers of Exilis (Fine Agrochemicals) and Maxcel (Interfarm UK) to ensure their availability this season. Together they successfully demonstrated the products' importance to UK apple growers to win the approval.
HDC tree fruit panel chairman and Hutchinsons agronomist Nigel Kitney said: "This is fantastic news for the industry as it ensures that apple growers are not totally reliant on hand thinning for the season ahead. Although we have only had one year's experience of using these products in UK conditions, initial results were encouraging when applied both at 8mm and 12mm fruitlet diameter."
He added: "However, I would urge growers to experiment with the products at different fruitlet sizes to help us to fine tune their use for future years".
This year, the HDC is funding a trial at East Malling Research to compare five thinning strategies on Gala. It will include using hand thinning and 6-benzyladenine at different fruitlet sizes and a combination of both. The results will be made available next winter well before the 2012 growing season, when it is hoped full approval for the two thinning agents may be secured in the UK.