Promising new and existing fruit tree rootstocks are selected, grafted to commercial cultivars, and planted in coordinated uniform trials across North America. Each trial is evaluated by the local project coordinator for survival, precocity, productivity, size control, anchorage, root suckering, pest resistance, adaptability, and production efficiency. Some trials may include adaptability to specific or varied orchard systems and/or technologies. Trials generally are conducted for 10 growing seasons. Specific trial establishment, management, and data collection protocols are developed by the technical committee for each fruit species. Vegetative growth is typically measured by changes in trunk cross-sectional area, tree height, and canopy spread. Reproductive performance is typically measured by bloom precocity, yield, yield efficiency, and fruit quality parameters (e.g., size, soluble solids, etc.). Season-specific factors such as climatic data and/or observations on unusual climatic events, as well as annual pest and disease pressure, are also recorded.
Each trial has a designated coordinator who collects, archives, and analyses data for all sites for the duration of the trial. Data are processed annually for progress reports and shared with trial cooperators and the full membership at the annual meeting. Standard statistical analyses are performed on all data, and for each trial, results are usually summarized for two publications that describe the 1) orchard establishment and 2) mature orchard management phases.
