Off Type Couch?
In vegetative established couch varieties like Tifdwarf, Tifeagle, Tifgreen and Champion, off-type couch may occur over time in putting greens. Two major reasons given for the occurrence of these off-types are 1) mutations occur due to genetic instability, and 2) contamination of the desirable plant materal with a foreign source. In a recently published article (Capo-chichi, et al. 2005) the authors were able to induce off-type couch in Champion and other vegetative couch varieties with repeated applications of dinitroaniline herbicides. From a research perspective these mutational changes resulted in genetically diverse off-types that could be important in evolutionary processes regarding couchgrass off-types. From a management perspective avoiding overuse or excessive use of dinitroaniline herbicides may delay off-type occurrance in vegetatively established greens.
Reference:
1. Capo-chichi, L.J.A., J.M. Goatley Jr., W. Philley, J. Krans, D. Davis, A. Kato, and E. van Santen. 2005. Dinitroaniline-induced genetic changes in bermudagrass. Crop Science 45, 1504-1510.