7 Tips on Apple Thinning Management
These seven tips are based on observations and research results from field trials conducted in the Annapolis Valley of Nova Scotia.
Sevin XLR Plus can be applied at desired amount of water per hectare with a fungicide from calyx until 12mm fruitlet growth stage.
Following Sevin XLR Plus with a fungicide, assess fruit set when fruitlet is approaching 10 mm in diameter. If more crop-load adjustment is needed, use Fruitone N or MaxCel in addition to the earlier application of Sevin XLR Plus.
For the more aggressive thinning, use Sevin XLR Plus at the high rate plus Fruitone-N (NAA) at 3 to 5 ppm at late petal fall. Recent trials with 100 ppm MaxCel + 5 ppm Fruitone N has improved return bloom.
No set of king fruit will require a more aggressive thinning program.
MaxCel in combination with Sevin XLR Plus is recommended for 8-12 mm fruitlet thinner for Northern Spy.
MaxCel and Fruitone N alone are effective at reducing the crop-load on McIntosh. Fruit in the cull size category can be reduced from 40 to 15%. These products are not recommended for thinning Red Delicious.
When trees are over-spurred, i.e. leaf to fruit ratio is low, chemical thinners will only do part of the required fruitlet removal. Special attention when pruning will be needed to get the ratio vegetative and fruit wood in balance. Follow-up hand thinning in July will likely be necessary for desired fruit size and colour for cultivars with growth habit similar to Honeycrisp.
Source: Doug Nichols. Orchard Outlook: Vol. 17, No. 7. May 2017. Pg. 10-11.
For the entire article and product guide, refer to pages 10 and 11 here: http://www.perennia.ca/wp-content/uploads/2017/05/Orchard-Outlook-May-24-2017.pdf