Sustainable Disease Control of Phytophthora cactorum in a Strawberry Nursery by Adapting the Growing System

The Netherlands is one of the most important countries for the production of strawberry transplants in Europe. Regulations for pesticide use and water quality become more strict each year, which is a challenge for this sector. Strawberry plants are grown from tips and raised in trays on a trayfield. One of the main plant diseases in strawberry is caused by Phytophthora cactorum. The dispersal of the disease is facilitated by sporangia and zoospores splashing from the surface of the trayfield onto the transplants in the trays. In this research, we compared, in three consecutive years, the traditional growing system with a new system in which the trays are elevated and splashes from the trayfield reaching the transplants are minimized. In two of the three years, we show that the new growing system without the use of any fungicide against P. cactorum performs as well as or even better than the traditional system with the use of the permitted pesticides. Data about Phytophthora occurring in air samples and in splash water collected at different heights support the hypothesis that the decrease in splash dispersal underlies the success of the elevated trayfield. This shows the potential of re-designing growing systems to become less dependent on pesticide use.