A meta-analysis of the effects of Striga control methods on maize, sorghum, and major millets production in sub-Saharan Africa

Parasitic Striga weeds severely damage cereal crops in sub-Saharan Africa (SSA), leading to yield losses in susceptible varieties. A range of Striga control methods are commonly recommended, including cultural practices, chemical herbicides, biological control agents, and host resistance, either as solo treatments or in combinations of these approaches (i.e., integrated Striga management [ISM]). A limited number of studies compared the relative efficacy of the recommended Striga control methods, or their combinations for ISM, in cereal crop production in SSA. The objective of this paper was to undertake a meta-analysis and provide a detailed comparison of the Striga control methods in the production of maize, sorghum, and the major millets, as a guide to effective Striga management. The study was conducted as a meta-analysis of 66 research articles that reported on various control measures. The following agronomic data were collected: grain yield (GY) response of the assessed crops and Striga parameters such as damage rating score (SDR) and emergence count (SEC). Maize varieties possessing Striga-resistant genes displayed high mean yield values at 2053.00 kg ha(-1), varying from 281.00 to 6260.00 kg ha(-1), and a mean SDR of 4.70, ranging from 2.00 to 7.00. Likewise, sorghum varieties with Striga resistance genes achieved greater GY with a mean yield response of 1738.00 kg ha(-1), ranging from 850.00 to 2162.00 kg ha(-1). A relatively low GY was achieved in maize and sorghum production when deploying ISM (e.g., cultural control + host resistance and host resistance + chemical herbicides) and chemical Striga control. Effective ISM and pre- and post-emergent herbicides have not yet been identified for Striga control and yield gains. Striga damage negatively affected GY in maize, as revealed by the significant correlation (r = -0.36, P < 0.001) between GY and SDR. A relatively weak correlation was detected in maize between GY and SEC (r = 0.003, P = 0.96). Sorghum GY was negatively correlated with SEC, although nonsignificantly (r = -0.30, P = 0.36). Few studies have evaluated Striga control methods in pearl millet and finger millet, limiting the opportunity for an effective comparison. The study recommends SDR as the best selection criterion for improving GY performance in maize, while SEC and SDR are the parameters of choice in sorghum selection programs for better GY under Striga infestation. Overall, the meta-analysis indicates that host resistance is the most effective method for controlling Striga infestation and boosting GY in maize and sorghum. There is an ongoing need for research into the best combinations of the reported control methods as a sound basis for the recommendation of an ISM package across target production environments of common cereals in Africa.