Soft fruit toolbox - Resistant and tolerant varieties
Using resistant and tolerant cultivars is an important tool of any IPM toolbox. The James Hutton institute has been researching the use of resistant and tolerant soft fruit varieties for several pest species and diseases for over 40 years.
Resistance gene (A10) discovered in raspberry and linked to the deterrence of the Large raspberry aphid (Amphorophora idaei) due to compounds in the waxy cuticle of leaves (Shepherd et al., 1999) is still used in the raspberry breeding programme.
Plant physical traits can provide resistance or tolerance to some insect pests (Mitchell et al., 2016). In raspberry, plant architecture and leaf hair density affect the abundance of aphids and two spotted spider mite (Tetranychus urticae) and spider mite egg-laying (Karley et al., 2015; Graham et al., 2014).
Root physical size and structure could provide resistance or tolerance to pests and diseases. In raspberry, reduced susceptibility to Phytophthora root rot is linked to increased root vigour (Mitchell et al., 2018). Root vigour might also contribute to varietal differences in tolerance of vine weevil (Otiorynchus sulcatus) damage. Imaging technologies are being used to develop non-destructive high throughput phenotyping methods aiming to fast-track soft fruit breeding (Williams et al., 2018).
Breeding plots provide a good source of genetic material to allow comparisons between varieties and their susceptibility to pests under different growing conditions (e.g. Blueberry pests in tunnel vs. open field conditions).