Selective Smutgrass Control and Forage Quality Response in Bermudagrass‐Dallisgrass Pastures1

Abstract

AbstractSmutgrass (Sporobolus poiretii Roem and Schult.), a prevalent and increasingly serious weed problem in pasture areas of the southeastern United States, cannot be selectively controlled in swards containing desirable forage species with the available recommended procedures. Dallisgrass (Paspalum dilatatum Poir.)‐bermudagrass (Cynodon dactylon (L.) Pers.) pasture swards, the most prevalent type of pastures in our region, were selected for uniform infestation of smutgrass and treated with atrazine [2‐chloro‐4‐(ethylamino)‐6‐isopropylamino)‐s‐triazine] at 4.48 and 8.96 kg/ha; bromacil (5‐bromo‐3‐sec‐butyl‐6‐methyluracil) at 2.24 and 4.48 kg/ha; and MSMA (monosodium methanearsonate) at 2.24, 4.48, and 8.96 kg/ha in the fall of 1970 and 1971. From 83 to 97% smutgrass control was obtained with a single application of atrazine or bromacil with no more than 38% injury to bermudagrass and 28% injury to dallisgrass. Maximum smutgrass control obtained with MSMA application was 63% which also resulted in 89% dallisgrass control. Forage quality determinations in the spring following smutgrass control indicated that total forage was more acceptable when smutgrass was controlled.