The Problem
Tropical signalgrass, also known as smallflowered alexandergrass, (Urochloa distachya, syns. Urochloa subquadripara, Brachiaria subquadripara) is a perennial grass commonly found in the state of Florida. This blanket-like grass has become a significant weed problem in Florida sod, golf courses and lawns. This grassy weed is very difficult to control with existing postermergence herbicides. In the past, a tank mix of MSMA and Sencor® provided some level of herbicide activity, but with inconsistent results. This was also compounded by bermudagrass phytotoxicity, making this a less desirable option.
What To Look For
Tropical signalgrass stems are usually trailing and creeping, rooting at the nodes. Leaf blades are flat, 0.3-0.5 inches wide and up to 0.75 inches in length. Both the leaf blade and sheath are hairy and the ligule has a short fringe of hairs. Flowering branches may reach 18 inches tall and produce 2-7 branches or “fingers” in the raceme of the seedhead. In the field, tropical signalgrass germination occurs when soil temperatures reach 77°F. A soil pH of 5-6, which is common in Florida soils, is required for germination. Moisture is required for seed germination, and the typical dry season in Florida can delay tropical signalgrass infestation.
The Solution
Tribute® Total is a postemergence herbicide that provides control of tropical signalgrass, as well as many hard-to-control weeds, in bermudagrass and zoysiagrass. Refer to the following points for successful control of tropical signalgrass with Tribute Total.
- Best control of tropical signalgrass is obtained with spot treatments of Tribute Total initiated in early fall
- To make a spot treatment, mix 0.073 oz. of Tribute Total per gallon of water and add appropriate spray adjuvant(s)
- Addition of ammonium sulfate (AMS) and methylated seed oil (MSO) to the spray will enhance the level of
control obtained
- Refer to the Tribute Total label for more information on adjuvant selection and rates
- Refer to the Tribute Total label for spray applications on limited areas: spot spray and zone broadcast applications
- Spray weeds until wet but avoid spray solution runoff and over-application
- Spot treatments may cause temporary yellowing and stunting to turfgrass
- For spot treatments, treat no more than 10,000 sq. ft. per acre
- Make a second application, if necessary, 2-3 weeks after the first application, or at weed regrowth
- Please refer to Tribute Total label for tropical signalgrass control for more information
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Solution sheet - Tropical Signalgrass |
