Postemergence Control of Field Sandbur (Cenchrus incertus) with Foramsulfuron.

The presence of field sandbur (Cenchrus incertus) in turfgrass is both aesthetically and physically detrimental due to the prolific production of sharp, shiny burs. Few postemergence herbicides exist for the effective and efficient control of this weed in managed turfgrass. Therefore, experiments were conducted at the Texas Tech Horticultural Greenhouse in Lubbock, TX in the spring of 2008 to quantify the efficacy of foramsulfuron with various spray adjuvants to control field sandbur. Five seeds were germinated in 10-cm square pots and grown to the five-leaf stage. Pots were arranged in the greenhouse in a randomized complete block design, with four replications of treatments. Treatments were applied using a CO₂ backpack sprayer equipped with XR8003VS nozzle tips and calibrated to deliver 304 L/ha at 220 kPa. Treatments were initiated on March 26, 2008 and consisted of single or sequential applications of foramsulfuron (0.15 kg ai/ha) alone or in combination with methylated seed oil (1.0% v/v), crop oil concentrate (1.0% v/v), or each of the two plus urea ammonium nitrate (UAN) (2.5% v/v). Sequential applications for each treatment were made 2 WAIT (weeks after initial treatment). Visual estimates of percent field sandbur control were taken 1, 2, 3, and 4 WAIT. Data were subjected to analysis of variance (ANOVA) and means were separated using Fisher’s Protected LSD at the 0.05 significance level. All treatments exhibited 43 to 63% control 1WAIT. Slightly higher control was observed among treatments containing spray adjuvants with foramsulfuron + COC treatments exhibiting 58 to 63% control 1 WAIT. All treatments provided > 89% control 3 WAIT. Control with foramsulfuron alone was equivalent to foramsulfuron plus spray adjuvants 3 WAIT. Sequential applications of treatments did not provide a significant additional increase in control 3 WAIT. All treatments provided 99% control 4 WAIT.