Foliar Diseases and the Associated Fungi in Rice Cultivated in Kenya
Everlyne M. Nganga,
Martina Kyallo,
Philemon Orwa,
Felix Rotich,
Emily Gichuhi,
John M. Kimani,
David Mwongera,
Bernice Waweru,
Phoebe Sikuku,
David M. Musyimi,
Samuel K. Mutiga,
Cathrine Ziyomo,
Rosemary Murori,
Lusike Wasilwa,
James C. Correll,
Nicholas J. Talbot
Affiliations
Everlyne M. Nganga
Department of Botany, School of Physical and Biological Sciences, Maseno University, Kisumu P.O. Box 3275-40100, Kenya
Martina Kyallo
Biosciences Eastern and Central Africa-International Livestock Research Institute (BecA-ILRI) Hub, ILRI Complex, Old Naivasha Road, Nairobi P.O. Box 30709-00100, Kenya
Philemon Orwa
Department of Water and Agricultural Resource Management, School of Agriculture, University of Embu, Embu P.O. Box 6-60100, Kenya
Felix Rotich
Department of Water and Agricultural Resource Management, School of Agriculture, University of Embu, Embu P.O. Box 6-60100, Kenya
Emily Gichuhi
Kenya Agricultural and Livestock Research Organization, Kaptagat Road, Loresho, Nairobi P.O. Box 57811-00200, Kenya
John M. Kimani
Kenya Agricultural and Livestock Research Organization, Kaptagat Road, Loresho, Nairobi P.O. Box 57811-00200, Kenya
David Mwongera
Kenya Agricultural and Livestock Research Organization, Kaptagat Road, Loresho, Nairobi P.O. Box 57811-00200, Kenya
Bernice Waweru
Biosciences Eastern and Central Africa-International Livestock Research Institute (BecA-ILRI) Hub, ILRI Complex, Old Naivasha Road, Nairobi P.O. Box 30709-00100, Kenya
Phoebe Sikuku
Department of Botany, School of Physical and Biological Sciences, Maseno University, Kisumu P.O. Box 3275-40100, Kenya
David M. Musyimi
Department of Botany, School of Physical and Biological Sciences, Maseno University, Kisumu P.O. Box 3275-40100, Kenya
Samuel K. Mutiga
Biosciences Eastern and Central Africa-International Livestock Research Institute (BecA-ILRI) Hub, ILRI Complex, Old Naivasha Road, Nairobi P.O. Box 30709-00100, Kenya
Cathrine Ziyomo
Biosciences Eastern and Central Africa-International Livestock Research Institute (BecA-ILRI) Hub, ILRI Complex, Old Naivasha Road, Nairobi P.O. Box 30709-00100, Kenya
Rosemary Murori
Department of Entomology and Plant Pathology, Division of Agriculture, The University of Arkansas System, Fayetteville, AR 72701, USA
Lusike Wasilwa
Kenya Agricultural and Livestock Research Organization, Kaptagat Road, Loresho, Nairobi P.O. Box 57811-00200, Kenya
James C. Correll
Eastern and Southern Region Office, International Rice Research Institute, ILRI Complex, Old Naivasha Road, Nairobi P.O. Box 30709-00100, Kenya
Nicholas J. Talbot
The Sainsbury Laboratory, Norwich Research Park, University of East Anglia, Norwich NR4 7UH, UK
We conducted a survey to assess the occurrence and severity of rice blast and brown spot diseases on popular cultivars grown in the Busia, Kirinyaga, and Kisumu counties of Kenya in 2019. Working with agricultural extension workers within rice production areas, we interviewed farmers (n = 89) regarding their preferred cultivars and their awareness of blast disease, as this was the major focus of our research. We scored the symptoms of blast and brown spot and assessed the lodging, plant height, and maturity of the crops (days after planting). Furthermore, we collected leaf and neck tissues for the assessment of the prevailing fungal populations. We used specific DNA primers to screen for the prevalence of the causal pathogens of blast, Magnaporthe oryzae, and brown spot, Cochliobolus miyabeanus, on asymptomatic and symptomatic leaf samples. We also conducted fungal isolations and PCR-sequencing to identify the fungal species in these tissues. Busia and Kisumu had a higher diversity of cultivars compared to Kirinyaga. The aromatic Pishori (NIBAM 11) was preferred and widely grown for commercial purposes in Kirinyaga, where 86% of Kenyan rice is produced. NIBAM108 (IR2793-80-1) and BW196 (NIBAM 109) were moderately resistant to blast, while NIBAM110 (ITA310) and Vietnam were susceptible. All the cultivars were susceptible to brown spot except for KEH10005 (Arize Tej Gold), a commercial hybrid cultivar. We also identified diverse pathogenic and non-pathogenic fungi, with a high incidence of Nigrospora oryzae, in the rice fields of Kirinyaga. There was a marginal correlation between disease severity/incidence and the occurrence of causal pathogens. This study provides evidence of the need to strengthen pathogen surveillance through retraining agricultural extension agents and to breed for blast and brown spot resistance in popular rice cultivars in Kenya.
