Green stem is a disorder of soybean characterized by delayed senescence of stems with normal pod ripening and seed maturation. Two types of field experiments were conducted to test the relationship between green stem and Bean pod mottle virus (BPMV) and explore other potential factors that may be involved in the disorder. One experiment evaluated green stem and BPMV in collected leaf samples from individual plants in several commercial soybean fields during three growing seasons. Maturing plants (pods with full green seed) and leaf samples were tested by enzyme-linked immunosorbent assay (ELISA) for BPMV. The percentage of marked plants infected with BPMV in some fields was higher than the incidence of green stem at harvest maturity. Many plants infected with BPMV did not develop green stem, and conversely, many plants that had green stem were not infected with BPMV. An analysis of the numbers of plants in four possible classes indicated that green stem disorder was independent of BPMV infection (P = 0.98). Another experiment completed over two growing seasons in field cages showed that green stem developed without BPMV infection. BPMV infection did not increase green stem incidence in comparison to the caged controls. Insect feeding did not have an effect on level of green stem incidence. The exact cause or causes for the green stem disorder remain unknown.

Green stem is a disorder of soybean [Glycine max (L.) Merrill] that causes the stems to remain green, nonsenescent, and moist, although pods and seeds are fully ripe and dry. The disorder is a nuisance for producers because it complicates harvesting of soybeans by significantly increasing the difficulty in cutting the affected plants during harvest. The cause of the disorder is unknown; however, differences in relative sensitivity to the disorder have been observed. The primary objective of this research was to evaluate the relative sensitivity among commercial or near-commercial cultivars from private and public soybean breeding organizations in replicated variety tests in Illinois. In 31 tests at Dekalb, Monmouth, and Urbana, IL, during 2001 to 2004, 1187 different MG I (maturity group)-MG IV conventional and glyphosate[N-(phosphonomethyl)glycine]-tolerant, cultivars were visually evaluated. There were significant differences in sensitivity among cultivars in 29 of the 31 tests, indicating that genetic variability among cultivars for green stem sensitivity exists. This variability may provide a basis for breeding for low sensitivity to the green stem disorder. Total levels of green stem disorder incidence varied over years and locations. Herbicide management systems did not appear to affect the levels of green stem incidence.