Effective Biocontrol of Rice Blast through Dipping Transplants and Foliar Applications

Ruth Murunde,Gideon Ringo,Xiangming Xu,Louisa Robinson-Boyer

doi:10.3390/agronomy12030592

Ruth Murunde, Gideon Ringo + Show 2 more

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https://doi.org/10.3390/agronomy12030592

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Abstract

Rice (Oryza sativa) is an increasingly popular food in Africa. As much as 30% of yields are lost due to blast disease caused by Magnaporthe oryzae. Several commercial biopesticides of Bacillus subtilis, Trichoderma asperellum, and Serratia sp. strains were evaluated under field conditions for their effects against rice blast and yield at one site in Kenya and three sites in Tanzania in 2020 and 2021. Each biopesticide was applied as a dipping treatment at transplanting, post-transplanting foliar spraying, or both. Using biopesticides not only achieved blast control but also increased grain yield, particularly in low-production regions in Tanzania, with a yield increase of >100%. For higher-production sites with low disease pressure, the yield increase through biopesticides over the untreated control was limited, although significant disease suppression was achieved. Dipping alone was sufficient to suppress disease and improve yield unless disease pressure was high. The differences among the three biopesticides varied with site/year but generally were small. Improved yield using biopesticides is unlikely to result solely from reduced blast development, but also from improved plant development. The present study suggests that these commercial biopesticides should be applied in rice production, particularly in subsistence farming.

Highlights

Rice (Oryza sativa L.) is an increasingly popular food in Africa and is grown in40 African countries, with substantial increased productivity in recent times [1]
The present study aims to expand these pilot studies to assess the effects of several commercially available biopesticides on rice blast, as well as plant development and grain yield, under field conditions in Kenya and Tanzania
Several commercial biopesticides were evaluated for their effects against rice blast and yield in Kenya and Tanzania

Summary

Introduction

Rice (Oryza sativa L.) is an increasingly popular food in Africa and is grown in40 African countries, with substantial increased productivity in recent times [1]. African rice producers need to increase their production capacity drastically to meet the ever-increasing demand. The current rice yield (2.8 to 3.8 t/ha) achieved in Kenya is above average in Africa but still behind Asia Tanzania is the most important rice-production zone in East Africa. Rice production in Tanzania is still characterized by low productivity, with average yields of 1.5–2.8 t/ha. This low productivity is due in large part to the fact that small-scale low-technology (but high-labor) farmers account for ca. On these farms, fertilizers are often not used because of the cost, limiting yields

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