REACTION OF SUERTE PASPALUM-ATRATUM TO HERBICIDES

Seedlings of 'Suerte' Paspalum atratum, a new pasture grass, were eval uated in 1994 at Ona, FL for reaction to herbicides. Seedling density was 0.0 plants/ft(2) (or/m(2)) 70 d after preemergence treatment with clomozone, fluometuron, and imazethapyr vs. 4.0/ft(2) (43/m(2)) for no herbicide. Preemergence diuron, metribuzin, trifluarlin, and norflura zon also gave substantially lower densities than no herbicide. Posteme rgence (28 d) treatment with 2,4-D and dicamba + 2,4-D reduced Suerte density somewhat (to 2.4/ft(2) or 26/m(2)). Density with dicamba alone (avg 3.3/ft(2) or 36/m(2)) was not significantly different from that with no herbicide. Spraying 2-yr old Suerte pasture in 1994 with dicam ba + 2,4-D, glyphosate, hexazinone, nicosulfuron, metasulfuron-methyl, sulfometuron-methyl, or triclopyr resulted in little injury and no ki ll. Fluazifop resulted in injury but no kill, while higher rates of gl yphosate resulted in injury and an average 53% kill. On 18 Apr. 1995, 2 rates of fluazifop and 4 rates of glyphosate were applied to 2-yr ol d Suerte pasture at 2 locations. After 70 d, all treatments had lower densities of live plants than with no herbicide, except for glyphosate at the lowest rate. Percentage kill from glyphosate = -1.3 + 18.6X or 16.6 X, where X = active ingredient in lb/A or kg/ha. On 27 June 1995 , the 7 treatments above were applied to pasture, with glyphosate appl ied both with and without an additional 10 lb/A (11 kg/ha) of (NH1)(2) SO6. Addition of (NH1)(2)SO4 increased efficacy of glyphosate at the l ower rats of application. There was no difference between April and Ju ne application for percentage dead Suerte seedlings, but dicamba, hexa zinone, metsulfuorn-methyl, and triclopyr may be useful for control of specific weeds in established Suerte pasture. Glyphosate at 2 lb/A (2 .2 kg/ha) with 10 lb/A (11 kg/ha) (NH4)(2)SO4, or 3 lb/A (3.4 kg/ha) o f glyphosate alone, in water containing antagonistic salts, provided a bout 90% kill of established Suerte.