CATT as a sustainable method for disinfestation of strawberry mother planting stock

From 2009 Controlled Atmosphere Temperature Treatment (CATT) is scaled up to a commercial level and widely applied by Dutch producers of strawberry (Fragaria × ananassa) mother planting stock. CATT is a non-chemical and sustainable method to disinfest plant material from insect pests. Frigo plants are treated after storage and before planting during 48 h at a temperature of 35°C and 50% CO2. This results in an excellent disinfestation and a mortality of 99.8% of the strawberry tarsonemid mite (Phytonemus pallidus). As a side effect, the two spotted spider mite (Tetranychus urticae) was killed as well. This method provides a healthy production of highly qualified strawberry runners in the field. Recently it was found that also the plant parasitic nematodes Meloidogyne hapla and Pratylenchus penetrans can be considerably reduced by application of CATT. For an effective killing of these nematodes however, temperature must be raised to at least 40°C. In several experiments the optimum for a high mortality of both tarsonemids and nematodes has been studied. This leads to an adapted CATT of 20 h at a temperature of 35°C and 50% CO2 followed by 20 h at a temperature of 40°C. Application of these optimized CATT can prevent further dispersion of Meloidogyne hapla nematodes in the strawberry chain. Until now no harmful irreversible results of this adapted CATT on vitality of mother plants are found but will be checked thoroughly in the field on runner production in further experiments.