Sericea Lespedeza in Hay Fields

 

Sericea lespedeza is a perennial plant, unlike common or Korean lespedeza commonly used in pastures and hayfields.  It is a prolific seed producer, and produces chemicals which inhibit the growth of other plants.  From a forage standpoint, it produces compounds called tannins which bind protein, making them unavailable for digestion by livestock.  These tannins also dramatically reduce palatability.  Interestingly, there are varieties of low-tannin sericea lespedeza that have been effectively used as forage in pasture settings.  Unfortunately, those are not the varieties commonly seen in our part of the world.

If sericea lespedeza is in a hayfield, can the field be harvested for hay?  The short answer is yes, but there are some things producers need to know.  First, it is recommended that sericea be harvested for hay when the plant is about 12 to 18 inches tall.  This will maximize quality and possibly reduce palatability issues for early cut forage.  Second, flowering and seed set occur in mid to late-summer.  If the sericea has not set seed, it is unlikely to spread into hay feeding areas.  However, producers should monitor these areas for sericea and other weeds and treat problems as they arise.  If it does get a toehold, producers should aggressively target the elimination of plants as soon as they are noticed.

Based on research from K-State, tannin content peaks in late summer.  Tannin content was found to be less in sun cured hay than in fresh vegetation.  However, additional research at K-State found that tallgrass prairie forage containing about 20 percent sericea lespedeza harvested in late July, which corresponds to the budding stage of sericea and highest levels of tannin content, markedly decreased hay dry matter intake of cows compared to cows fed non-contaminated hay.  Within 9 days of being fed sericea contaminated hay, forage dry matter intake was seven times less compared to cows being fed non-contaminated hay.

So, the implications of harvesting and feeding hay contaminated with sericea lespedeza include reduced hay intake, and cattle sorting out the sericea due to reduced palatability.  Sericea will probably spread if hay is harvested when seeds are present.

Sericea lespedeza should be controlled in hay fields and other areas.  Hay harvest or mowing will not control the spread of sericea in hay fields.  MU weed specialists have identified several chemical treatments that are effective in controlling this noxious weed.  Choice of chemicals is related to the time of year and stage of plant maturity.

If you are unsure about what this plant looks like, it can be viewed at http://weedid.missouri.edu and scroll down to sericea lespedeza for more information.

Source: Gene Schmitz, Livestock Specialist