Smutgrass (Sporobolus poiretii) Control in South Florida

Abstract

Various chemical and cultural treatments were evaluated for smutgrass [Sporobolus poiretii (R.&S.) Hitchc], control and their effects on pangolagrass (Digitaria decumbens Stent.) and bahiagrass (Paspalum notatum Flügge). Herbicide treatments were dalapon (2,2-dichloropropionic acid) at 1.7, 3.3, and 5.0 kg/ha with Sunoco HE spraying oil at 0, 9.4, 19.0 and 37.0 L/ha. Five weeks after herbicide treatment plots were clipped (clipped vs. nonclipped) and fertilized (0 vs. 112 kg/ha N). Increasing dalapon from 1.7 to 5.0 kg/ha increased smutgrass control and decreased the number of smutgrass plants/plot. Pangolagrass ground cover generally increased with fertilization, as the rate of dalapon increased up to 3.9 kg/ha. Bahiagrass ground cover decreased with rates of dalapon above 1.7 kg/ha. Increasing the rate of oil increased bahiagrass ground cover after 90 days. Nitrogen applied 5 weeks after dalapon treatment and semi-annually for 5 yr generally decreased ground cover of smutgrass and bahiagrass, but increased pangolagrass. Clipping treated smutgrass plants increased pangolagrass and bahiagrass ground cover while decreasing the ground cover of smutgrass.

Influence of Hexazinone on Pensacola Bahiagrass Growth and Crude Protein Content

“…However, multiple reports have shown that the dalapon application rates required for consistent smutgrass control were highly injurious to Pensacola bahiagrass, the principle desirable forage in Florida. To illustrate, >80% smutgrass control often required dalapon applied at 3.3 kg ha −1 , which caused injury to Penascola bahigrass at this application rate ranged between 30% (Brecke 1981) and 50% (Mislevy and Currey 1980). Considering the large openings in the sward caused by smutgrass removal and the slow recovery due to bahiagrass injury, the use of dalapon often resulted in an overall increase of pasture weeds.…”

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

“…2 Another option tested is the mowing of smutgrass plants treated with herbicide, but, despite some increased control, 1 it is regarded as an unnecessary expense. 5 Smutgrass responds rapidly following defoliation.…”

Effect of Mowing and Hexazinone Application on Giant Smutgrass (Sporobolus indicusvar.pyramidalis) Control

“…The use of the herbicide dalapon was only slightly more effective than cultural control methods. The application rate of dalapon required to achieve Ͼ80% smutgrass control also reduced bahiagrass stand density to 50% ground cover (Mislevy and Currey 1980). Although dalapon was the only selective herbicide with activity against smutgrass, the marginal tolerance of bahiagrass to dalapon reduced the effectiveness of this control program.…”

“…Smutgrass is a prolific seed producer, generating as many as 45,000 seeds per plant and more than 1,400 seeds per panicle (Currey et al 1973). Additionally, smutgrass produces seed continually throughout the growing season with flowering, immature seed, mature seed, and shattering occurring simultaneously on the same panicle (Mislevy and Currey 1980). In Florida, two species of smutgrass exist: Sporobolus indicus (smutgrass) and Sporobolus indicus var.…”

“…Mowing, fertility management, intensive rotational grazing, and use of the herbicide dalapon were once the only viable control options. Mowing, in combination with nitrogen fertilizer, has shown confounding effects by reducing the populations of both smutgrass and bahiagrass (Mislevy and Currey 1980). Others have found that mowing alone did not reduce smutgrass density; rather, it facilitated seed dispersal (McCaleb and Hodges 1971;McCaleb et al 1963).…”