Figure 2.
Common Bermudagrass Cover Following Various Eradication Regimens at the Texas A&M University Turfgrass Field Lab in College Station, TX during the Summer of 2015 and Early 2016.
Compared to North Carolina, Texas treatments generally provided superior bermudagrass control in the summer immediately following application; however, unacceptable control was observed the following spring. Excluding irrigation-incorporated dazomet (262 pounds/acre) and nontreated-tilled, all treatments resulted in < 13 percent cover through 5 WAIT in Texas (Figure 2). Additionally, all dazomet treatments including fluazifop + glyphosate resulted in 0 percent cover at this time. However, a pronounced increase in bermudagrass cover was observed in many Texas plots from 5 to 42 WAIT. At 42 WAIT, treatment regimens utilizing only dazomet application(s) did not provide acceptable bermudagrass control (65 to 99 percent cover), suggesting turfgrass managers cannot solely rely on this fumigant for eradication.
Similar to North Carolina, applying fluazifop + glyphosate prior to dazomet increased bermudagrass control. At 42 WAIT, the only dazomet treatments providing acceptable control included fluazifop + glyphosate pretreatment coupled with application at the high rate, and tillage- incorporation (4 percent cover). Additionally, tarping the area following this treatment did not improve bermudagrass control, suggesting this step may be excluded during renovations. Treatment regimens only including fluazifop + glyphosate provided comparable long-term control across locations when applied 3 times (< 5 percent cover); however, 2 applications resulted in
TPI Turf News March/April 2019
acceptable control in North Carolina (5 percent cover), but not in Texas (39 percent cover).
Differing control between locations may be due in part to more favorable bermudagrass growing conditions in North Carolina shortly after dazomet application, while Texas conditions were generally superior over the entire 10 to 11-month research period. Warmer winter climatic conditions and an extended growing period in Texas may have created more favorable conditions for common bermudagrass recovery.
It should also be noted that grass was not re-planted in these plots after treatment as would be the case in sod fields. Tis could have created more favorable conditions for common bermudagrass regrowth by excluding plant competition from the subsequent turfgrass stand, and ultimately reduced long-term efficacy. Future research is needed to determine optimal re-grassing timing following dazomet application.
Across locations, fluazifop + glyphosate application prior to dazomet was required for acceptable bermudagrass control. Across both locations, this pretreatment followed by tillage-incorporated dazomet at 525 pounds/acre, resulted in < 10 percent bermudagrass cover at the final evaluation date. Tarping after tillage did not improve efficacy, and consequently is not recommended for renovations to save management resources and reduce potential dazomet-
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