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

Donald Scott,Meva Tahiry Randrianjafizanaka,Julie Diane Scholes,Robert P Freckleton,Jean Augustin Randriamampianina,Patrice Autfray

doi:10.1002/ece3.8085

Abstract

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.

Highlights

Species of the genus Striga, which belongs to the parasitic plant family Orobanchaceae (Joel et al, 2007), are among the most economically significant weeds affecting food security within sub-Saharan Africa (SSA) and cause severe losses in many staple crops (Scholes & Press, 2008)
Given the importance of rice variety, legume crops, and Striga density within adjacent fields, we provide evidence to contribute to the multifactor approach to Striga through integrated Striga management
The analysis shows, that no single factor influences Striga density to the degree that it can be considered a panacea for control

Summary

Introduction

Species of the genus Striga, which belongs to the parasitic plant family Orobanchaceae (Joel et al, 2007), are among the most economically significant weeds affecting food security within sub-Saharan Africa (SSA) and cause severe losses in many staple crops (Scholes & Press, 2008). Striga has resulted in reported yield losses of between. Estimates of economic losses from Striga range from between $111 and $300 million per year for rice (Rodenburg et al, 2016) and $383 for maize (Woomer & Savala, 2008). Estimates of the size of the areas affected vary between 50 and 100 million ha annually (FAO, http://www.fao.org/). Seeds can remain dormant within the seed bank for many years, often remaining viable for decades, enabling long-term persistence in affected areas (Parker, 2013)

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