Bacterial leaf streak disease of rice: A silent constraint to rice production in Uganda

Abstract

Bacterial leaf streak disease (BLS) caused by Xanthomonas oryzae pv oryzicola is one of the emergent biotic constraints to rice production in Africa. The disease, which can cause yield loss of up to 60% on susceptible cultivars, was observed in Uganda in the rice growing districts of Namutumba, Butaleja and Iganga in 2014. As such there is limited data on the distribution of bacterial leaf streak disease in rice growing areas of Uganda. Using a systematic sampling survey, 176 rice fields at tillering to panicle initiation stages in 14 rice growing districts of Uganda were assessed for the prevalence of BLS disease. Results show a high prevalence of bacterial leaf streak disease, where 71.4% of the districts surveyed had the disease. Data collected also revealed significant differences (P < 0.001) in BLS incidence and severities between the districts surveyed. The results further indicated that rice fields where improved varieties and clean seeds were planted had very low incidences and severity. The high prevalence of BLS disease in the rice growing districts may be due to existence of highly virulent BLS pathogens, favourable environment (high humidity and warm temperature) and cultivation of susceptible local rice genotypes. Poor rice residue management, poor field hygiene and utilization of home saved rice seeds by majority of the farmers could also account for the wide occurrence of BLS disease since these lead to the build-up of primary inoculum. For sustainable management of this disease, there is need to create awareness on the wide occurrence of BLS disease in Uganda, educate farmers on management of the disease, understand the population structure of BLS pathogen in Uganda and identify genetically stable sources of resistance to the pathogen under Uganda’s conditions.