Nitrogen Fertilizer, Oil, and Surfactant Adjuvants with Nicosulfuron

Abstract

Urea and ammonium nitrate are components of 28% nitrogen liquid fertilizer (UAN) that is often used as an adjuvant in addition to surfactants or oils with herbicides. Ammonium nitrate and/or UAN fertilizer enhancement of nicosulfuron phytotoxicity to large crabgrass or yellow foxtail depended upon the associated oil or surfactant adjuvant. Ammonium nitrate reduced the effectiveness of most block copolymers but not other surfactants with nicosulfuron for large crabgrass. Urea never enhanced and often reduced surfactant and oil adjuvant enhancement of nicosulfuron. Ammonium nitrate or UAN, but not urea, enhanced nicosulfuron phytotoxicity to yellow foxtail when the spray carrier contained sodium bicarbonate. These research results indicated that enhancement of nicosulfuron efficacy from UAN is mainly from the ammonium nitrate component. However, the benefit to nicosulfuron from UAN or ammonium nitrate depended upon the associated surfactant or oil adjuvants.

Spray Deposits from Nicosulfuron with Salts that Affect Efficacy1

“…Pluronic P-85 is a paste-type block polymer giving a uniform deposit upon spray droplet drying ( Figure 5A). Pluronic P-85 alone was an effective surfactant with nicosulfuron but was highly antagonized by ammonium nitrate but not ammonium sulfate, bicarbonate, or chloride in the spray solution (Nalewaja et al 1998). Nicosulfuron spray deposits containing Pluronic P-85 and salts that had a separation of the Pluronic P-85 from the salts ( Figures 5C, 5E, 5F, 5J, 5K) generally related to effective control with nicosulfuron.…”

“…The discussion of the spray droplet residues will refer extensively to efficacy data from previous publications by Nalewaja et al (1995Nalewaja et al ( , 1998 and to unpublished data when referring to sodium bicarbonate. X-77.…”

“…Various salts and surfactants could interact to produce spray deposits where the herbicides, solutes, and leaf cuticle may or may not be proper for effective herbicide absorption. Scanning electron micrographs (SEM) were taken of spray deposits from nicosulfuron applied with surfactants and salts known to affect phytotoxicity in previously published (Nalewaja et al 1995(Nalewaja et al , 1998 and unpublished research to determine possible relations between spray deposit characteristics and efficacy.…”

Postemergence Weed Control with Rimsulfuron and Various Adjuvants in Potato (Solanum tuberosum)1

“…Rimsulfuron activity on green foxtail increased from less than 10% to more than 90% as surfactant concentration increased from 0.0008 to 0.1% (Green 1996). The type of adjuvant also is important for herbicide efficacy (Nalewaja et al 1995(Nalewaja et al , 1998. In greenhouse studies, yellow foxtail [Setaria glauca (L.) Beauv.]…”

Activator Adjuvants1

“…Ϫ from the (NH 4 ) 2 SO 4 then associates with the Ca ϩϩ to form calcium sulfate. Ammonium nitrate but not urea appears to function similarly (Nalewaja et al 1998).…”