Successful integration of UV-C in IPM strategy strawberry
Previous research showed that a 3 times a week (Monday, Wednesday, Friday) night time UV-C application of 110 J/m2 is effective in controlling powdery mildew. But to be successful at growers the UV-C strategy has to be compatible with the current used IPM strategy, in which multiple beneficial insects are used to control the most common pests. So the UV-C application may not harm the beneficial insects.
In a spring cultivation (plastic greenhouse; planting date: 24 March 2020) with Elsanta, we validated our developed UV-C – IPM strategy on a larger scale. We compared two compartments. April 6th we started in one compartment with UV-C applications (UV-C – IPM), the plants in the other compartment were exposed to a conventional IPM strategy (IPM). The table underneath shows the used crop protection measures in both objects. The conventional IPM strategy contains 8 chemical sprayings, the UV-C – IPM strategy contains only 3 chemical sprayings.
Table 1: Crop protection measures in both objects (IPM vs UV-C – IPM). The chemical sprayings are showed in red.
During the cultivation cycle we weekly monitored pests and beneficials in both objects. The predatory mite Amblydromalus limonicus, used to control thrips and whitefly, showed a good population build-up in both objects. At May 20th predatory mites were found on all spots. Due to this good settlement of predatory mites we didn’t have thrips problems. The population build-up of predatory mites in both objects was excellent and so wasn’t disturbed by the 3 times a week UV-C applications.
A mildew assessment at the end of the cultivation cycle showed that both strategies were able to keep the average mildew infection rate below 10%. In the IPM compartment we noticed an infection rate of 9,3%, the UV-C – IPM strategy gave an infection rate of 7,0%. The UV-C - IPM strategy was equally able to control powdery mildew in comparison with a conventional used IPM strategy. June 19th we counted the amount of aphids per leaf. In the UV-C – IPM object less aphids were observed. This result is different from previous day time application trials. The doses used during the day time UV-C application were not sufficient in controlling aphids. Night time application shows an inhibitory effect on the aphid population.