Screening Mungbean Accessions for Susceptibility to Soybean Fungal Diseases in Iowa

Abstract

United States’ sales of mungbean ( Vigna radiata L. Wilczek) products and other plant-based protein sources exceeded $1 billion in 2020. Most mungbean consumed in the United States is imported, but it has considerable potential as a domestic crop. Its heat and drought tolerance give U.S. farmers an alternative to soybean and corn crop rotation. Mungbean is a 60- to 90-day crop with similar equipment needs, chemical inputs, and storage requirements to those of soybean and has a developed market. Its vulnerability to diseases in the United States is unknown. Thus, we compared the susceptibility of 10 mungbean genotypes to 8 soybean diseases in the lab. We also monitored disease occurrence in sentinel field plots in Iowa. Mungbean accessions showed a wide range of susceptibility to Cercospora kikuchii, Colletotrichum gloeosporioides, Diaporthe caulivora, Fusarium oxysporum, F. virguliforme, Macrophomina phaseolina, Pythium sylvaticum, and Sclerotinia sclerotiorum. Symptoms of frogeye leaf spot, sudden death syndrome, and Rhizoctonia root and crown rot, common soybean diseases, were observed on mungbean in the field; isolates were identified as Cercospora sojina, F. virguliforme, and Rhizoctonia solani, and Koch's postulates were conducted. C. sojina and F. virguliforme are newly reported as causing disease in field-grown mungbean.