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

Abstract

Smutgrass (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.

Smutgrass Control with Herbicides in Turfgrasses

“…These results differ from those reported in Mississippi 3where 88% control was obtained from atrazine applied at the 4.4 kg/ha rate. Atrazine applied at either 6.7 or 9 kg/ha as a single treatment controlled 81 to 99% of the smutgrass when treatments were made in November 1972, January 1973, or 1974 (Table 1). Atrazine at 4.4 kg/ha rate controlled 84% of the smutgrass when applied in November 1972 but only 40% when the same rate was applied in October of the same year.…”

“…There fore, these chemicals would cause undesirable characteristics if applied to home lawns and golf courses. Atrazine and bromacil gave selective smutgrass control when applied to dallisgrass (Paspalum dilatatum Poir) and bermudagrass pastures in Missis sippi (3).…”

Use of Rotational Stocking in Combination With Cultural Practices for Smutgrass Control—A Florida Case Study

“…Our primary goal was to demonstrate that defoliation of smutgrass plants and increased stock density could be used to reduce the extent of the smutgrass problem on cattle ranches without disrupting normal management activities. Secondary goals included: 1) Reducing the vigor of smutgrass plants, 2) Comparing the effect of treatments on the number and size of smutgrass plants, 3) Reducing the number of smutgrass plants reaching maturity and producing seed, and 4) Maintaining acceptable body condition and weight gain on grazing animals.…”

Smutgrass (Sporobolus poiretii) Control in Pastures with Herbicides

“…Ryegrass (Lolium perenne L.) was successfully established by seeding 2 weeks after dalapon application in the fall. Smith et al (17,18) showed that fall applications of atrazine at 4.5 kg/ha or bromacil at 2.2 kg/ha gave at least 83% smutgrass control, while causing 28 and 32% or less injury to dallisgrass (Paspalum dilatatum Poir.) and bermudagrass, respectively, 36 weeks after treatment.…”