Impact of insecticide and pollinator-enhancing substrate applications on cocoa (Theobroma cacao) cherelle and pod production in Cote d'Ivoire

Cocoa yield in the major cocoa-producing countries is far below potential levels. It has been shown that apart from poor soil fertility, inadequate genotypes and pest and disease incidence, this yield gap is caused by below-optimum pollination levels. On 3 Ivorian cocoa farms, during the six months preceding the main harvest season of 2018-2019 (August 2018 until January 2019), we used generalized mixed models to investigate how the creation of a pollinator-friendly environment by applying rotting organic material (banana pseudostems) to cocoa fields, combined with and without insecticide applications, influences cocoa production. It was found that banana pseudostem treatments had a positive effect on cherelle production but that this effect was only observed in plots treated with insecticide to protect cherelles against sap-sucking mirids, at the beginning of the experiment. Furthermore, although we did not find significant differences in cherelle wilt rates between treated and control plots, we did not observe a significantly higher accumulated number of mature pods that were produced on trees treated with substrate and untreated control trees during the 25 week experimental period. The pollination-enhancing effect of the substrate on cherelle production in sprayed plots was significantly higher in trees that were close ( < 1 m) to the holes to which the substrate was applied, compared to trees that were further away from these holes. Reduced rainfall towards the end of the minor rainy season of October - November, concurred with a decrease in the number of flowers but also with a decrease in fruit set rate. Soils of all experimental farms had nutrient levels considered to be inadequate for cocoa production, which can explain why the increase in cherelles ( + 75 % and + 50 % in trees respectively close to and further away from substrate holes) did not result in significant increases in mature pods. Our results suggest that closing the pollination gap will close the cocoa yield gap, only when other factors that prevent cherelles to develop into mature pods, are addressed.

Jaar van publicatie:2020

Toegankelijkheid:Closed