Apple Carbohydrate Thinning Model
The Apple Carbohydrate Thinning Model can provide utility when determining thinner rates and application timing. The general carbohydrate balance the model calculates has been found to correlate well with tree sensitivity to natural drop and with sensitivity to chemical thinners. Cool sunny periods of good carbohydrate supply leads to reduce natural drop and less response to thinners. Cloudy hot periods give carbohydrate deficits and lead to stronger natural drop and stronger response to thinners.
The carbohydrate models does not apply during bloom or petal fall. Fruit must be actively growing before we apply the model. Since carbohydrate demands do not influence thinning at bloom or petal fall, it makes these periods a relatively safe time to begin thinning, compared to when the fruit are between 6 and 18 mm in size.
The carbohydrate model is described in detail at http://newa.cornell.edu/index.php?page=apple-thin, for more information http://newa.nrcc.cornell.edu/apple_thin_help.html.
Learn even more about the carbohydrate model: http://www.nyshs.org/pdf/fq/2007-Volume-15/Vol-15-No-3/Using-an-Apple-Tree-Carbohydrate-Model-to-Understand-Thinning-Responses-to-Weather-and-Chemical-Thinners.pdf
Predicting Fruitset Model
The Predicting Fruitset Model can provide additional insight when determining utility and reapplication of thinners. The model is based on the assumption that setting fruitlets will grow faster than those that will drop as a result of chemical thinners or other factors. Visit the following links for more information:
- http://msue.anr.msu.edu/news/use_precision_cropload_management_tools_to_target_apple_crop_load
- http://msue.anr.msu.edu/topic/apples/horticulture, scroll down to the ‘thinning’ section and review spreadsheet and PDF.
Precision Pruning
Precision pruning uses the latest science to help growers confidently prune high-density blocks to achieve a target-crop load. Pruning high-density trees requires more than several thinning and heading cuts to open up a canopy and remove old wood. To get the greatest yield return, modern orchards need to be pruned to a target-bud load. These targets are unique for each block and will complement the thinning program. Unknown variables including weather, labor and biennial bearing cultivars can radically influence results. Precision pruning offers a science-based alternative to reduce flower buds, improve light distribution and control tree size. This approach minimizes the guess work and will help to mitigate the influence of external variables. Learn how other growers are using this to achieve their goals, http://www.goodfruit.com/achieving-the-optimal-crop-load/.
