Pilot study of the potential of the repellent cinnamamide to reduce woodpigeon damage to oilseed rape

Abstract

Woodpigeons (Columba palumbus) cause significant damage to oilseed rape, especially between January and March. No effective means of controlling this damage currently exists. The use of a chemical repellent, such as cinnamamide, which makes the crop temporarily unpalatable may offer a viable solution.

The potential of cinnamamide to protect growing oilseed rape from woodpigeon damage was assessed by comparing damage to the crop in untreated and cinnamamide-treated 20 x 20m plots laid out on a 9 ha field that was regularly used by a flock of over 500 woodpigeons. Damage to the rape was assessed before cinnamamide was applied and twice weekly thereafter. Damage to the new inner leaves was considered separately to the older, outer leaves. Loading and persistence of cinnamamide on the leaves was monitored at application and then twice weekly from samples collected during damage assessments. Despite a low initial loading of cinnamamide and low persistence of the compound after spraying, damage to the inner leaves of treated plants after application was significantly less than damage to the inner leaves of untreated plants (p<0.05) and this was reflected later in the trial in a decline in damage to the outer leaves of treated plants (p<0.05).

No signs of phytotoxicity were seen on treated leaves during the trial. However, cinnamamide did not completely protect the rape and in some plots treated rape received considerable damage. This was probably because these plots were damaged before the repellent was applied, and were therefore accessible to the birds, and also because of the low persistence of the compound on the leaf due to harsh weather conditions with substantial precipitation.