The aim of a ZRMS is to reduce residue levels to below the limit of detection by avoiding the use of traditional crop protection products during the period of apple development from post-bloom to harvest and use cultural, biological and other non-conventional methods during apple development instead. The use of conventional products is restricted to the period from post-harvest to petal-fall.
The key feature of the zero residue system is to reduce the populations of pest and disease during the dormant season to ensure negligible inoculum carry over from one season to the next. The key factors, vital to success are:
- Choice of suitable orchards
- Starting at the right time
- Implementation of the management programme
- Meticulous and sustained orchard monitoring
Choice of orchard
It is important that orchards selected for zero residues programmes have a low incidence of pests and diseases, especially powdery mildew, at the outset.
- Those with a history of disease or pest problems should be avoided.
- The orchard must be well managed and trees trained and pruned to ensure an open canopy for good air circulation and spray penetration.
- Trials experience so far has been on Cox, Gala, Red Pippin, Braeburn and Bramley and on scab resistant cultivars where there has been good success.
- It is important not to be too ambitious initially.
- Select one or two orchards on the farm to manage according to the system to gain experience before embarking on a wider adoption of the system.
When to start
It is important to start the ZRMS in the autumn, shortly after harvest to implement the important late season and dormant period tasks that are vital to success.