S19 - Session O3 - Elicitor application in strawberry results in long-term increase of plant resilience without yield loss

Authors: Kirsten Leiss *, Sanae Mouden, Johanna Bac-Molenaar, Iris Kappers, Ellen Beerling

For integration of elicitor application into current IPM strategy increasing plant resilience against pests, we investigated repeated elicitor treatments in a strawberry everbearer nursery and cropping cycle under glass. During nursery methyl-jasmonate (MeJA) was applied every three weeks, testing induction of defenses with plant bioassays. Thrips damage, as well as reproduction by spider mites, whitefly and aphids were strongly reduced upon elicitor treatment. Subsequently, we applied MeJA every three weeks, or based on scouting of pests, during a whole cropping cycle. Thrips leaf bioassays and LC-MS leaf metabolomics were applied to investigate defense induction. Thrips leaf damage was lower for both MeJA application schemes compared to the control except the last weeks. Thrips damage decreased from vegetative to mature plants during the cropping cycle. Surprisingly, growth during production was not affected by MeJA application as were fruit yield and quality. LC-MS leaf metabolomics showed a strong induction of vegetative plants decreasing during maturation of plants towards the end of cultivation. Mostly flavonoid and phenolic glycosides known as plant defense compounds were induced upon elicitor application. While induced defense decreased with maturation of plants constitutive defense increased as measured in the leaf metabolome of control plants. Our data propose that young relatively small plant stages lack constitutive defense necessitating an active JA defense response. As plants mature constitutive defense metabolites seem to accumulate providing a higher level of basal resistance. The results obtained have important implications for cultivation of strawberry showing that both vertical integration of different pest management tactics as well as horizontal integration controlling several different pests concurrently, can be realized. Moreover, regular application of elicitors during the crop cycle forms a very promising pest management tool as part of a sustainable IPM strategy in strawberry.