Supermarkets are very exacting about the size, consistency and appearance of the fruit in their stores and so apple growers must achieve the premium size grading in order to satisfy their customers.
Usually the crop will need some management to achieve this and thinning soon after flowering can help in this instance. The use of the chemical thinner MaxCel, which contains 6-benzyladenine, can increase growers’ returns by reducing the reliance on hand-thinning, improving fruit size and quality.
Using MaxCel as a thinning agent for crops soon after flowering will increase fruit sizing and also reduce alternate bearing. “Apple growers won’t be totally reliant on expensive hand thinning and can benefit from getting the right balance of crop load and fruit size,” explains Andy Makings of Interfarm UK Ltd.
Andy explains MaxCel is a cytokinin-type plant growth regulator. “This group of naturally occurring plant hormones affects a number of processes in plants, including apical dominance, axillary bud growth, cell division, cell growth and leaf senescence. MaxCel prevents fruitlets below a certain size from developing further, whilst fruitlets above a certain size will grow on. Expensive hand-thinning costs can be minimised. By using MaxCel, the fruit size can also be increased due to less competition for nutrients plus an enhanced rate of cell division and growth. Enhancement of return blooms the following year helps reduce any trend in the orchard towards alternate bearing.”
MaxCel needs to be applied at the correct time and under optimum conditions. Optimum timing is when the king fruitlet has a diameter of 7-15 mm, with the optimum range being 10-12 mm in size. It should be applied at the start of a warming period when the maximum daily temperatures for the 2-3 days following application are expected to be at least 15-18° C. It should not be applied when temperatures are below 15° C. One application can be made per year and the latest time of application is when the king fruitlet is 15mm.
It is recommended on all varieties of apples at dose rates of 3.75 to 7.5 litres/ha. The dose rate varies according to how easy or hard the variety is to thin. It is ready for the grower to use and requires no additional adjuvants. Adequate coverage of fruit and foliage without excessive run-off is important, and water volumes should be adjusted for tree size and spacing. Water volumes of 1000 litres/ha in air assisted sprayers will give adequate coverage of fruitlets and foliage. It is fully compatible with IPM programmes.
