Past and Future Epidemiological Perspectives and Integrated Management of Rice Bakanae in Korea

Abstract

In the past, rice bakanae was considered an endemic disease that did not cause significant losses in Korea; however, the disease has recently become a serious threat due to climate change, changes in farming practices, and the emergence of fungicide-resistant strains. Since the bakanae outbreak in 2006, its incidence has gradually decreased due to the application of effective control measures such as hot water immersion methods and seed disinfectants. However, in 2013, a marked increase in bakanae incidence was observed, causing problems for rice farmers. Therefore, in this review, we present the potential risks from climate change based on an epidemiological understanding of the pathogen, host plant, and environment, which are the key elements influencing the incidence of bakanae. In addition, disease management options to reduce the disease pressure of bakanae below the economic threshold level are investigated, with a specific focus on resistant varieties, as well as chemical, biological, cultural, and physical control methods. Lastly, as more effective countermeasures to bakanae, we propose an integrated disease management option that combines different control methods, including advanced imaging technologies such as remote sensing. In this review, we revisit and examine bakanae, a traditional seed-borne fungal disease that has not gained considerable attention in the agricultural history of Korea. Based on the understanding of the present significance and anticipated risks of the disease, the findings of this study are expected to provide useful information for the establishment of an effective response strategy to bakanae in the era of climate change.

Map-Based Cloning and Characterization of a Major QTL Gene, FfR1, Which Confers Resistance to Rice Bakanae Disease

“…BD seems to become more prevalent due to temperature rises caused by climate change in temperate regions. Agronomic measures to control BD include treatment of seed with fungicides, foliar fungicide sprays, treatment of seed with biological control agents such as Trichoderma spp., crop rotation, and planting resistant varieties [ 11 ]. Recently, Azadirachta indica leaf aqueous extract-based silver nanoparticles (AgNPs) displayed inhibition of the mycelial growth of Fusarium fujikuroi and potential seed disinfection without toxicity to the seeds during germination, which indicated that AgNPs are an effective alternative strategy for controlling BD [ 56 ].…”

“…BD is caused by the fungal pathogen Fusarium fujikuroi , which can thrive in temperatures as high as 35 °C [ 1 ], allowing this disease to reproduce more rapidly and spread as temperatures increase due to climate change. The infected plants show elongated shoots, yellowing leaves, stunting, seedling rot, and barren ears [ 11 ]. Conidia formed at the tillering stage are dispersed by rain splashes or the wind during the flowering stage and infect the floral organs, infecting the seeds at later stages [ 11 ].…”

“…The infected plants show elongated shoots, yellowing leaves, stunting, seedling rot, and barren ears [ 11 ]. Conidia formed at the tillering stage are dispersed by rain splashes or the wind during the flowering stage and infect the floral organs, infecting the seeds at later stages [ 11 ]. These infected seeds are the major source of disease transmission, although the pathogen can also overwinter in dry soil [ 11 ].…”

“…Conidia formed at the tillering stage are dispersed by rain splashes or the wind during the flowering stage and infect the floral organs, infecting the seeds at later stages [ 11 ]. These infected seeds are the major source of disease transmission, although the pathogen can also overwinter in dry soil [ 11 ]. The main method of controlling BD is disinfection of the seeds by chemical fungicides [ 1 , 11 ]; however, fungicide-resistant strains have emerged, making its control difficult [ 12 , 13 , 14 , 15 ].…”

“…These infected seeds are the major source of disease transmission, although the pathogen can also overwinter in dry soil [ 11 ]. The main method of controlling BD is disinfection of the seeds by chemical fungicides [ 1 , 11 ]; however, fungicide-resistant strains have emerged, making its control difficult [ 12 , 13 , 14 , 15 ].…”