S16 - Session O2 - Advances in precision crop load management of apple

Authors: Terence L. Robinson *,

We are leading a USA national SCRI project to develop precision crop load management strategies and machines to manage the number of fruits per tree to exactly the economic optimum. We have done physiological experiments to define the biological potential of yield and fruit size of 'Gala' and 'Honeycrisp' apple cultivars in 4 climates (West, Mid-West, North-East and South-East USA) to estimate the economic optimum number of fruits per tree. Our results show that the dry, high light climate of WA generally can support a higher crop load than the eastern USA growing regions. To achieve the optimum fruit number per tree we employ: 1) precision pruning to remove flower buds to a pre-determined flower bud load; 2) precision chemical thinning through sequential chemical thinning sprays guided by the use of computer models to adjust the dose and timing of chemical application and to assess the effect of the chemical sprays shortly after application to inform re-application; and 3) precision hand thinning to guide human workers to leave an exact number of fruits per tree. At each step in reducing fruit bud load, flower load or fruitlet load, we are developing computer vision to streamline the counting of buds, flowers and fruitlets. The geo-referenced information on each tree is uploaded to the cloud and then communicated to human workers to guide their work in reducing crop load to the optimum.