Irrigation and Soil Surfactants Affect Abamectin Distribution in Soil

Abstract

Nematodes are microscopic, soil‐dwelling organisms that adversely affect many turfgrass systems, including golf course putting greens. Abamectin controls many nematode species in golf course putting greens; however, high sorption to accumulated organic matter near the soil surface in established turfgrass systems may limit its distribution in soil, thereby limiting its efficacy. Field research was conducted on ‘A1/A4’ creeping bentgrass and ‘Champion’ ultradwarf bermudagrass putting greens to evaluate abamectin distribution in soil following treatment regimens including abamectin application (37 g a.i. ha–1) alone, or tank‐mixed with soil surfactant (Revolution) in tandem with various irrigation timings to promote downward distribution. Laboratory research was also conducted to evaluate 14C‐abamectin soil distribution via treatments comprised of various combinations of simulated irrigation amounts and timings, as well as soil surfactant type (Dispatch or Qualibra) and timing with respect to abamectin application. Abamectin distributed similarly in soil across turfgrass species in field research. At 7 d after treatment (DAT), all irrigation–soil surfactant regimens increased abamectin distribution to the 0‐ to 2.5‐cm soil depth compared with broadcast spray alone; however, no evaluated regimen resulted in >2% of the applied abamectin movement beyond 2.5 cm. In laboratory experiments, 14C‐abamectin soil distribution was affected most by soil surfactant at 3 DAT, with Qualibra increasing distribution (8.2 to 18.4% of applied) to 7.5 cm depth compared with Dispatch or no surfactant. As in field research, irrigation amounts and timings generally affected 14C‐abamectin similarly. This research highlights practices to enhance distribution into the profile, thereby increasing bioavailability and efficacy.

Soil surfactants influence fungicide movement in United States Golf Association putting green soil

“…Gannon et al. (2017) found similar results to our study. They determined that the soil surfactant Qualibra increased vertical distribution of abamectin in a soil column.…”

“…Latin and Ou (2018) determined that the soil surfactant Revolution, alone, had no effect on downward movement of propiconazole, azoxystrobin, pyraclostrobin, thiophanate‐methyl, or cabendazim in a field setting. In contrast, Gannon, Jeffries, and Ahmed (2017) found that the addition of the soil surfactant Qualibra (Syngenta) increased abamectin distribution in soil. Many soil surfactants reduce the surface tension between solution and soil particles, which is likely why abamectin distribution in the soil increased in this study.…”

Movement of seed- and soil-applied fluopyram in soil columns

“…Although the mobility of abamectin is low it is more toxic to M. incognita than fluopyram (Faske and Starr, 2006;Faske and Hurd, 2015), therefore, only a small amount was needed to cause a similar incidence of M. incognita mortality. The limited downward movement of abamectin in this study is comparable to other soil column and field studies (Gruber et al, 1990;Gannon et al, 2017). Though the downward movement of fluopyram was limited to 10 cm soil depth, the concentration detected would inhibit J2 infection of tomato (Faske and Hurd, 2015).…”

Nematicide effects on non-target nematodes in bermudagrass

“…Abamectin had intermediate effects on nematodes, altering the community structure of free-living nematodes and causing disturbance to the soil ecosystem as indicated by a shift to a slightly less mature soil Nematicide effects on non-target nematodes in bermudagrass food web. Effects on nematodes were generally detected later in the season and could be explained by the characteristic slow movement of this formulation through the thatch layer of turfgrass (Gannon et al, 2017). High cp nematodes were mildly affected by abamectin.…”