Identifying existing management practices in the control of Striga asiatica within rice-maize systems in mid-west Madagascar

Infestations by the parasitic weed genus Striga result in significant losses to cereal crop yields across sub-Saharan Africa. The problem disproportionately affects subsistence farmers who frequently lack access to novel technologies. Effective Striga management therefore requires the development of strategies utilizing existing cultural management practices. We report a multiyear, landscape-scale monitoring project for Striga asiatica in the mid-west of Madagascar, undertaken over 2019-2020 with the aims of examining cultural, climatic, and edaphic factors currently driving abundance and distribution. Long-distance transects were established across the middle-west region of Madagascar, over which S. asiatica abundance in fields was estimated. Analysis of the data highlights the importance of crop variety and legumes in driving Striga density. Moreover, the dataset revealed significant effect of precipitation seasonality, mean temperature, and altitude in determining abundance. A composite management index indicated the effect of a range of cultural practices on changes in Striga abundance. The findings support the assertion that single measures are not sufficient for the effective, long-term management of Striga. Furthermore, the composite score has potential as a significant guide of integrated Striga management beyond the geographic range of this study.

Automated summary

A monitoring project in the mid-west of Madagascar revealed that factors such as crop variety, legumes, precipitation seasonality, mean temperature, and altitude play significant roles in driving the abundance of Striga asiatica. The study suggests that single measures are insufficient for long-term Striga management and that a composite management index may be a useful guide for integrated management practices beyond the geographic scope of the study.