Using plant extracts to reduce asexual reproduction of apple scab (Venturia inaequalis)

Abstract

The aim our research was to develop effective methods for organic apple farming, based on the use of plant extracts to control the asexual reproduction of Venturia inaequalis. Plant extracts of artemisinin, chelidonine, thymol, and populin tested in vitro under laboratory conditions significantly slowed down the germination of V. inaequalis conidia. During a 2-year study under field conditions, the effect of 1% populin, an extract from black poplar buds, on apple scab was tested in parallel with synthetic fungicides and a nopesticide regime on Golden Delicious and Jonathan apples. Populin significantly reduced the number of scabbed leaves and fruits on Golden during the first year of the field evaluation compared to synthetic fungicides and had a similar effect as synthetic fungicides in the second year of application. The mean number of scabbed leaves on Jonathan was reduced significantly by both synthetic fungicide and populin applications in both years; however, while synthetic treatments did not reduce the number of scabbed fruits in the first year, populin significantly reduced the number of lesions on fruits. According to these results, we concluded that the severity of apple scab on commercial apple cultivars can be reduced using 1% populin plant extract as a cheap, alternative, and highly available method of reducing the conidial spores. The estimated costs of spraying populin per hector on apple plantations were much lower than costs for synthetic fungicides. Populin application may allow elimination or reduction of synthetic fungicide use and enable efficient organic apple farming. © TÜBİTAK.