Floral bud distortion in soybean and incidence in Central India

Abstract

We describe a peculiar and often harmful budding disorder in soybean, leading to huge yield loss in India. To determine the prevalence of floral distortion in soybean, an extensive random roving survey was undertaken in the soybean-growing regions of Madhya Pradesh, Maharashtra and the adjoining part of Karnataka states during two successive seasons of kharif (monsoon-planted) crops – Oct 2010 and Sept 2011. The average rate of the disorder ranged from 8.0% to 14.6% and severity from 2.0 to 90.0% during 2010 and 2011, respectively. Affected plants were found to have either no or deformed pods and distorted flowers, and they remained green after maturity. All the soybean varieties grown in the surveyed region (i.e. JS 335, JS 93-05, JS 73-23, JS 95-60, AMS-MB-5-19, CO-2, Bragg, JS 10-44, Samrat) were affected by the disorder. The PCR-based diagnosis revealed the absence of phytoplasma in symptomatic soybean samples.

Keywords: Glycine max, chlorosis, green stem, thickening and twisting stem, yield loss.