Shade tolerance of St. Augustinegrass cultivars

Abstract

The objectives of this research were to rank the relative shade tolerance of some new st. augustinegrass (Stenotaphrum secundatum) cultivars and to determine what levels of shade the various cultivars can tolerate. Two consecutive studies were conducted in a glasshouse at the University of Florida Turfgrass Research Envirotron. Cultivars tested were 'Bitter Blue', 'Floratam', 'Palmetto', 'Seville', and '997-6'. Grasses were grown in full sun or under shade structures that provided 30%, 50%, or 70% shade. In trial 1, 'Seville' and '1997-6' generally provided best performance under increasing shade, with worst responses seen in 'Floratam'. 'Seville' and '1997-6' were predicted to maintain an acceptable quality rating of 6 at all shade levels. In trial 2, 'Floratam' again had lowest visual quality scores. At 30% shade, 'Seville', 'Palmetto', and 'Bitter Blue' ranked in the highest category, while only 'Seville' and 'Bitter Blue' had highest rankings at 50% shade. Reduced density was a major factor in turf decline as shade increased. Most of the cultivars performed best under some degree of shade. With the exception of 'Floratam', acceptable visual scores were maintained at shade levels exceeding 60% in trial 1 and up to 61% in trial 2.