Knotroot Foxtail: A Major Issue in Bermudagrass Hay Production

Much of Tennessee, particularly West Tennessee, is well-suited for production of bermudagrass hay.  An increasing number of producers across our state have been successful producing high-quality bermudagrass hay in small bales for sale at a premium to horse owners, municipal zoos, and other buyers.  Weed management has always been a challenge in bermudagrass production.  However, that challenge has greatly increased in recent years for many producers in West Tennessee due to the spread of knotroot foxtail, a fast-growing, perennial weedy grass.  The grass not only reproduces by seed, as is the case with the annual foxtails, but it also produces rhizomes, or underground stems.  The key problem with this weed and the other foxtails is that the bristly seed heads in hay cause serious problems with mouth ulcers in horses.

 

Becky Muller (Shelby County Extension Agent),  Jeff Via (Fayette County Extension Director)  Trevor Israel ( Extension Assistant – Weed Management) , and Neil Rhodes (Professor and Extension Weed Management Specialist) have teamed-up to work toward solutions for producers affected by this costly weed.  During the winter of 2012, problem hay fields in several West Tennessee locations were sampled.  Dormant foxtail clumps were exhumed and inspected for the presence of the tell-tale rhizomes.  As expected, knotroot foxtail was confirmed in numerous locations.  The team visited with researchers and Extension Specialists  in other southern states where knotroot foxtail has been present for much longer than in Tennessee, and learned that although a number of investigators have conducted research on this weed over the past 2 to 3 years, the best herbicide options have only given suppression.

 

In spring, 2012, the team worked closely with a number of producers and encouraged them to implement a sequential program of Pastora + glyphosate, followed by a second application of Pastora, with the goal of seed head suppression.  Where properly implemented, the program did suppress seed heads and allow for cleaner hay for the first 2 to 3 cuttings.  However, the program is expensive and quite injurious to bermudagrass.  And, the weed rebounded in late summer. 

 

Efforts in 2013 have included numerous farm visits to work with affected producers, educational  meetings, on-farm, replicated research trials in the spring and fall, and a fact sheet that is currently in development.   It is hoped that these and other future efforts will lead toward effective, affordable solutions to this problem, thereby increasing the viability of this high value agricultural enterprise in Tennessee.

                                   

 

Jeffery D. Via