Sudden death syndrome (SDS), a disease in soybean plants, quickly spread across the southern United States in the 1970s, eventually reaching most agricultural areas of the US.
[2] Sudden death syndrome (SDS) has become one of the most impactful yield-reducing diseases in North American soybeans.
[3] Currently, the disease affects an area stretching from South Dakota to North Carolina, putting the majority of American soybean producers at risk.
[7] If the conditions are right (cool and wet), these symptoms can appear suddenly, causing large yield reductions.
[2] Blue fungal masses, found along with the foliar and stem symptoms, are strong diagnostic indicators for SDS.
[2] F. virguliforme overwinters as asexual macroconidium and chlamydospores and currently, no research has found a successful sexual stage with this pathogen.
From the V1 to R1 stages (seedling to first flower) of soybean growth, the fungus colonizes within the plant cortex and only goes up the stem a few inches above the soil surface.
The ability to control and react to as many of these factors as possible is key to protecting a soybean crop from SDS.
[2] Toxins are produced by the fungus when it colonizes the cortex and are sent up the stem to the leaves, causing the above-ground symptoms around first flower during mid-summer.
[15] It is important to note that not all seed companies give information regarding the impacts that SDS has on their soybean varieties.
Due to tight schedules and unpredictable spring weather patterns in the Midwest and Great Plains, it can be hard to not plant soybeans as soon as possible.
However, when possible, growers should consider waiting one or two weeks after typical early planting dates to allow soil to warm and dry, which will help protect the seedlings from being infected by F. virugliforme.
While this can be unrealistic for large growers, a recommendation is a quick rinsing of tires and equipment when moving to different areas or farms.
[16] It is important to note that lowering soil pH below 6.5 leaves soybeans more vulnerable to brown stem rot.
-Tillage: No-till systems are particularly vulnerable to SDS,[17][13] as the soil remains cooler and wetter due to not being tilled.
While there are benefits to no-till systems, it may be beneficial to consider light tillage prior to planting in cooler and wetter years to help open-up soil to the wind and sun.
[11] For this reason, a deep tillage that disrupts surface soil is recommended in fields that have been known to have SDS problems in the past.