Potato Review

14 POTATO REVIEW NOVEMBER/DECEMBER 2020 TRAP CROPS species of trap crops have been used - Solanum sisymbriifolium (sticky nightshade) and Solanum scabrum (African nightshade). S. sisymbriifolium can reduce PCN densities up to 80% but has been di cult to establish in- eld. S. scabrum establishment and use is less well understood in the UK, but comes from the tropics and higher altitudes, so may be better suited to UK climes. With Solanum scabrum, the group hypothesised that deeper sowing might work better than shallow, so have decided to compare establishment from two planting depths: 1.5cm and 3cm. ese solanaceous crops have not been selected over many generations to make them suitable for cultivation. Rather, they are wild plants recently brought into service. In the wild, such seeds would grow from inside their fruit, or inside animal dung. So, whilst small seeds would usually be drilled shallowly, they often fail to emerge. Using hand-held cameras and drones, the group are measuring trap crop ground cover and sharing this via their WhatsApp group and at meetings. PCN counts were taken before sowing the trap crop and will be compared at after trap crop destruction. Initial findings So far, the take-home messages are that earlier sowing, avoiding water-logged soils and higher seeding rates appear to be more successful. Trap crop establishment has varied considerably between farms, but to the surprise of eld lab coordinator, AndrewWade, S. sisymbriifolium sown at 1.5cm deep has the highest ground cover. “I thought the scabrum would be more vigorous with more biomass,” he said. “Separate to the trial, I hand-sowed some scabrum on the side. at was on June 1st and it did really well, so it might need a higher seeding rate. Both were sown at the same seed rate in the trial.” e ndings may also disprove the group’s hypothesis that deeper sowing may work better than shallow. The challenges Agricultural advisor Ivan Grove, who runs independent consultancy Curious Raven, has been monitoring and managing the trial assessments. “Our trials were looking to quantify if a post early-harvest crop, for example forage rye, would give the trap crop time to establish and reach the 700g above ground biomass required.” Ivan Grove, Agricultural Advisor Aerial image of one site where the trials are next to each other. Aerial imaging is used for overall plot ground cover analysis and crop inspections. Solanum scabrum used as a trap crop.