Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/1995
Publication Date: N/A
Interpretive Summary: Brown spot of soybeans is a fungal disease that can be observed on leaves of plants. It is a common disease in the areas of the United States where soybeans are grown. The disease is known to reduce soybean production. The disease is caused by the fungus, Septoria glycines, and until now has not been reported on other legume crops such as mung bean, common bean and pea. The pathogen was thought to be limited to soybeans, and did not occur on other commercial crops. Twenty nine of 30 legume species tested developed leaf symptoms after inoculation with the fungus. This study provides information about the host range of this fungus. These findings are important because they provide new information about the ability of the fungus to cause disease on other plants. These results will be beneficial to research and extension scientists when working with this pathogen.
Technical Abstract: Thirteen genera representing 30 legume species, two weed species (Abutilon theophrasti and Ampelamus albidus), and five cultivars of soybean were inoculated with Septoria glycines in the field and greenhouse. Of these, 29 legume species and A. theophrasti had leaf symptoms. Only Cicer arietinum and C. leave were symptomless. Leaf symptoms were separated into three types. All Glycine spp. except one accession of G. tabacina (PI440994) had typical soybean brown spot lesions. Ten legume species with green cotyledons had small lesions. Six legume species and A. theophrasti had atypical symptoms. Incubated leaf samples from inoculated field and greenhouse-grown plants were used to count pycnidia with cirrhi. Species with small lesions and atypical synptoms had fewer pycnidia with cirrhi than those plants with typical brown spot lesions. Two isolates of Septoria spp. obtained from leaf lesions on A. theophrasti and C. leave were similar in conidia and pycnidia sizes when compared to an isolate from soybean. Both isolates caused typical brown spot lesions on soybeans.