New Emergency Approval of thinning agent in apples
Apple growers will welcome the news that the plant growth regulator for the chemical thinning of apples, Maxcel has been granted a 120 day emergency SOLA approval in the UK, starting on the 5th April 2011 and valid up to 2nd August 2011.
A lot of apple varieties look to have strong blossom this year and so there will be much more benefit from using Maxcel than last year. Combined with the extraordinarily good weather during flowering, many varieties could be in danger of over cropping. This can lead to problems with fruit size, stress and a reduction in return bloom. Maxcel selectively thins the crop by using inter fruitlet competition, reducing the number of fruits per tree and, because it is used earlier than hand thinning, it optimises fruit size and picking quality. Achieving premium size grading is important for marketing produce and enhancing fruit size alone can more than pay for the treatment. It also promotes strong return blooms for the following year, so it is not just the one benefit of fruit thinning, says Mike.
Mike Hutchinson advises that Maxcel needs to be applied at the correct growth stage of the crop and also when the weather is suitable. The decision to use Maxcel has to be made before the natural fruit drop starts. But if the crop looks as if it will require thinning, as many do this year, you just have to get on with it. This year spring is a few weeks early and care will be needed to get Maxcel on at the right time. In my experience the best results are achieved when fruitlet size is 10 mm and the weather warm and sunny. You have a reasonable range of fruitlet sizes to go for (7 to 12 mm) and it is generally warm enough already.
Provided that the king fruit is within the recommended size range, it is more important to apply Maxcel in the best conditions possible. It is worth going at 8mm or 14mm with the right conditions, rather than applying at 10mm in poor weather. I would advise that Maxcel is applied as a special treatment on its own and it does not need the addition of an adjuvant.
In terms of timing, the SOLA for Maxcel advises that it can be applied when the king fruitlet has a diameter of 7-15 mm, with the optimum range being 10-12 mm in size. Applications should be made at the start of the warming trend and the maximum daily temperatures for the 2-3 days following application are expected to be at least 15-18 C. Best results are achieved during warm weather when temperatures are between 20-25 C. Maxcel should not be applied when temperatures are below 15 C. One application can be made per year and there is a 90 day harvest interval.
Based on the active 6-benzyladenine, which is a naturally occurring compound, Maxcel is recommended on all varieties of apples at dose rates of 350-750 ml/100 litres of water. It is important to ensure adequate coverage of fruit and foliage without excessive run-off, with water volumes being adjusted according to tree size and spacing. Water volumes of 1000 litres/ha in air assisted sprayers will give adequate coverage of fruitlets and foliage. It is also important to use a water volume that allows for sufficient Maxcel to be applied, depending on the variety and its ease of thinning.
Maxcel is being marketed in the UK by Interfarm UK Ltd, an associate company of Sumitomo Chemical Company. HL Hutchinson is a distributor of Interfarm UK Ltd. The product is being supplied under the terms of the emergency approval as instructed by The Chemicals Regulatory Directorate (CRD). It will be accompanied by the relevant documentation required by CRD for this type of approval, including the CRD emergency approval certificate, which will give growers all the necessary information for the correct timing and usage of the product.