Immediate Irrigation Improves Turfgrass Safety to Postemergence Herbicides

Abstract

<jats:p>Summer annual grassy weeds such as goosegrass (<jats:italic>Eleusine indica</jats:italic> L. Gaertn.) continue to be problematic to control selectively with postemergence (POST) herbicides within turfgrass stands. In recent years, reduced performance by certain herbicides (e.g., foramsulfuron), cancellation of goosegrass-specific herbicides (e.g., diclofop-methyl), and cancellation and/or severe use reductions of other herbicides [e.g., monosodium methanearsonate (MSMA)] have limited the options for satisfactory control and maintenance of an acceptable (≤30% visual turfgrass injury) turfgrass quality. Currently available herbicides (e.g., topramezone and metribuzin) with goosegrass activity typically injure warm-season turfgrass species. The objectives of this research were to evaluate both ‘Tifway 419’ bermudagrass [<jats:italic>Cynodon dactylon</jats:italic> (L.) Pers. ×<jats:italic>Cynodon transvaalensis</jats:italic> Burtt-Davy] injury after treatment with POST herbicides, and to determine whether irrigating immediately after application reduces turfgrass injury. Treatments were control (± irrigation); topramezone (Pylex 2.8C; ± irrigation); carfentrazone + 2,4-D + dicamba + 2-(2-methyl-4-chlorophenoxy) propionic acid (MCPP) (Speedzone 2.2L; ± irrigation); carfentrazone + 2,4-D + dicamba + MCPP in combination with topramezone (± irrigation); metribuzin (Sencor 75DF; ± irrigation); mesotrione (Tenacity 4L; ± irrigation); simazine 4L (±irrigation); and mesotrione + simazine (± irrigation). Irrigated treatments were applied immediately with a hand hose precalibrated to apply 0.6 cm or 0.25 inch (≈6.3 L). Visual turfgrass injury for combined herbicide treatments for the irrigated plots was 6% 4 days after treatment (DAT), 12% 1 week after treatment (WAT), 17% 2 WAT, and 6% 4 WAT, whereas nonirrigated plots had turfgrass injury of 14% at 4 DAT, 31% 1 WAT, 35% 2 WAT, and 12% 4 WAT. Irrigated pots had normalized differences vegetative indices (NDVI) ratings of 0.769 at 4 DAT, 0.644 at 1 WAT, 0.612 at 2 WAT, and 0.621 at 4 WAT, whereas nonirrigated plots had the lowest (least green) turfgrass NDVI ratings of 0.734 at 4 DAT, 0.599 at 1 WAT, 0.528 at 2 WAT, and 0.596 at 4 WAT. These experiments suggest turfgrass injury could be alleviated by immediately incorporating herbicides through irrigation.</jats:p>

Differences in selectivity between bermudagrass and goosegrass (Eleusine indica) to low-rate topramezone and metribuzin combinations

“…Topramezone at 10 g ha −1 plus metribuzin at 100 g ha −1 was observed to control E. indica 90% to 100% (Lindsey et al 2020). Kerr et al (2019aKerr et al ( , 2019b sought to reduce bermudagrass response to topramezone at 12 g ha −1 with or without metribuzin at 420 g ha −1 by immediate post-treatment irrigation. Irrigation at 0.6 cm within 1 min of spray application did not reduce initial bermudagrass injury but slightly improved recovery as assessed at 4 WAIT in South Carolina and Alabama (Kerr et al 2019a).…”

Applications of topramezone and SpeedZone®for POST goosegrass (Eleusine indica) control in hybrid bermudagrass

“…However, irrigating following application compromised topramezone efficacy on goosegrass, resulting in 30% less control compared to nonirrigated plots. Kerr et al (2019a) observed a similar reduction in turfgrass injury when irrigating following application of topramezone (12.3 g ha -1 ), carfentrazone þ 2,4-D þ dicamba þ MCPP (500 g ha -1 ), and topramezone (12.3 g ha…”

“…Goosegrass is a pervasive weed of warm-season turfgrass. Many herbicides used for POST goosegrass control cause unacceptable injury to warm-season turfgrasses such as bermudagrass (Busey 2004;Cox et al 2017;Johnson 1980;Kerr et al 2019aKerr et al , 2019bMcCarty 1991;Nishimoto and Murdoch 1999). In turfgrass systems, loss of herbicides such as diclofop-methyl and monosodium methanearsonate has further limited options available for POST goosegrass control (Cox et al 2017;Kerr et al 2019aKerr et al , 2019bLeibhart et al 2014).…”

“…Many herbicides used for POST goosegrass control cause unacceptable injury to warm-season turfgrasses such as bermudagrass (Busey 2004;Cox et al 2017;Johnson 1980;Kerr et al 2019aKerr et al , 2019bMcCarty 1991;Nishimoto and Murdoch 1999). In turfgrass systems, loss of herbicides such as diclofop-methyl and monosodium methanearsonate has further limited options available for POST goosegrass control (Cox et al 2017;Kerr et al 2019aKerr et al , 2019bLeibhart et al 2014). Concomitantly, goosegrass resistance to PRE herbicides including oxadiazon (McElroy et al 2017) and prodiamine (McCullough et al 2013) in turfgrass is well documented (Heap 2020) and further challenges effective control.…”

Regrowth and ornamental traits of bermudagrass fertilized with sewage sludge

“…The highest dose of sewage sludge (1,428 g m -2 ) positively influenced the Normalized Difference Vegetation Index (NDVI), with an average of 0.53 (Figure 2A), 39.41% higher compared to control treatment (0 g m -2 ). This index can indicate when the lawn is exposed to stresses such as trampling/compaction, utilization, and water deficit (Kerr et al, 2019;Straw et al, 2020). NDVI can be used as an alternative to evaluate the DCGI in the turfgrass (Caturegli et al, 2020).…”