Destructive Disease of Soybean – Sudden Death Syndrome and White Mold – Observed by the State
Wednesday, December 23, 2015
By: Carl Bradley - University of Illinois
"Signs and symptoms of a few soybean diseases have begun to show up in the last few weeks in some areas of the state. Two of these diseases, sudden death syndrome (SDS) and Sclerotinia stem rot (a.k.a. white mold) certainly are going to cause economic losses in some growers’ fields this year.
Symptoms of SDS that currently are being observed are interveinal chlorosis and necrosis of the leaves (veins remain green while the tissues between the veins turn yellow and then brown). These symptoms look exactly like the foliar symptoms caused by a different disease, brown stem rot. Brown stem rot, however, will cause internal browning of the pith in soybean stems, while SDS does not affect soybean stems. On SDS-affected plants, the leaves will fall off eventually, while the petioles will remain attached to the stems and branches. In some cases, a bluish-white mass of spores of the SDS fungus (Fusarium virguliforme) may be observed on the roots. Although the foliar symptoms of SDS are now being observed, infection by the SDS fungus occurred during the seedling stage, not long after planting. The symptoms that are now being observed are the effect of toxins that the SDS pathogen produces that are phytotoxic.
Cool and wet weather after planting and the recent rainfall received in parts of the state were favorable for infection and disease development, and are the reasons why SDS incidence is high in some areas this year. The primary method of managing SDS is to choose the most resistant soybean varieties available."
Link to full study: Disease of Soybean – Sudden Death Syndrome and White Mold – Observed by the State