- Specification of end user needs for diagnostic services for optimal application of thinning agents in apple orchards.

- Selection of indicator genes for defining the optimal stage for the application of thinning measures.

- Specification of end user needs for diagnostic services regarding bitter pit development during apple fruit storage.

- Selection of indicator genes with predictive value for bitter pit development.

- Development of a method for quick and on-site testing of the activity of the selected indicator genes.

Background Thinning

Crop load thinning is now recognized as vital to the effective management of apple orchards. Virtually all apple varieties have a tendency to over produce (set) fruit by up to 70%. Failing to appropriately thin will result in fruit that is small and discolored, with a lower market value while also damaging the trees from over bearing. It will also cause “biennial bearing”.

This is when the tree only produces fruit every two years. Thinning is therefore vital to not only ensure a consistent size and quality for this year’s harvest, but also next year’s.

Background Bitter Pit

Bitter pit is a disorder which can severely affect the economic value of the fruit, reducing it to 40% of the production price. The incidence and severity of bitter pit are affected by variety, but within a variety bitter pit is related to harvest date and climate; in susceptible varieties, harvest of less mature fruit can result in higher bitter pit incidence, as can excessive pruning or high temperatures and/or droughty conditions during the growing season.

Indeed, there is evidence that over thinning can increase the likelihood of bitter pit.