Tuesday, November 6, 2007
170-3
The Role of Spray Adjuvants in Improving Efficacy of Foramsulfuron for Dallisgrass Control.
Gerald Henry, Texas Tech University, Department of Plant and Soil Science, Campus Box 42122, Lubbock, TX 79409-2122
Field experiments were conducted at Lake Ridge Country Club in Lubbock, TX in the summer of 2007 to quantify the efficacy of foramsulfuron with various spray adjuvants to control dallisgrass in a bermudagrass rough. Studies were located on established infestations of dallisgrass present in a common bermudagrass rough cut to a height of 5.0 cm. Plots measured 1.5 m x 1.5 m and were arranged in a randomized complete block design, with four replications of treatments. Treatments were applied using a CO2 backpack sprayer equipped with XR8004VS nozzle tips and calibrated to deliver 304 L/ha at 220 kPa. Treatments were initiated on June 22 and consisted of foramsulfuron (0.15 kg ai/ha) applied alone or in combination with methylated seed oil (1.0% v/v), crop oil concentrate (1.0% v/v), non-ionic surfactant (0.25% v/v), or each of the three plus urea ammonium nitrate (UAN) (2.5% v/v). Sequential applications for each treatment were made 1 WAIT (weeks after initial treatment). Visual estimates of percent dallisgrass control and bermudagrass phytotoxicity were taken 1, 2, 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. Bermudagrass phytotoxicity (< 10%) was recorded 2 WAIT, but recovery was observed by 3 WAIT. Preliminary control data indicated that the addition of spray adjuvants, regardless of type, increased dallisgrass control from 40 to 45% 4 WAIT. A further increase in control of 2.5% was observed with treatments containing UAN. Additional ratings will be conducted throughout the remainder of the year to determine long-term effects of these treatments.