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Bruce Burdick
1109 S. Birch St.
Albany, MO 64402
660-726-5610
Email: BurdickB@missouri.edu

Hundley-Whaley Center phone
660-726-3698

Objective: To determine the efficacy of Liberty treatments for weed control in field corn, and to compare Liberty treatments to established standard treatments for weed control in field corn.

Methods and Materials: The study was conducted at the Hundley-Whaley Research Farm at Albany, Missouri. It was designed as a randomized complete block study, replicated three times. There were nine treatments in the study, including the untreated check. All post treatments, except the Accent tank mixes, included 3 pounds of ammonium sulfate per acre. The herbicide treatments are in Table 1.

Table 1
---------------------------------------------------------
Treat
-ment
No.      Application    Herbicide      Product Rate/Acre
---------------------------------------------------------
  1      Early post     Liberty             20.5 oz
         Early post     Aatrex 4L           1.5 pt
  2      Early post     Liberty             20.5 oz
         Late post      Liberty             20.5 oz
  3      Pre            Aatrex 4L           3 pt
         Mid post       Liberty             20.5 oz
  4      Pre            Dual II             1.5 pt
         Mid post       Liberty             20.5 oz
  5      Pre            Dual II             1.5 pt
         Mid post       Liberty             20.5 oz
         Mid post       Aatrex 4L           1 pt
  6      Pre            Balance             2 oz
         Mid post       Liberty             20.5 oz
  7      Early post     Accent              0.66 oz
         Early post     Buctril/atrazine    2 pt
         Early post     AG98 surfactant     0.25 v/v
         Early post     UAN                 2 quart
  8      Pre            Bicep II            4.9 pt

Pioneer 34A55, Liberty Link, brand seed corn was planted at the rate of 27,500 seeds per acre into a conventionally prepared seedbed on May 19. The pre-emergence herbicides were applied the same day. The early post applications were made June 9, the mid- post applications were made June 12 and the late post treatment was made June 27.

Weed pressure ranged from moderate to heavy. Wild sunflower and giant foxtail were the two species contributing the heaviest pressure. Common waterhemp, lambsquarters, giant ragweed and velvetleaf were moderate in pressure. On June 9, these weeds ranged from "1 to 5" tall.

All herbicide applications were made with a Farmall C tractor equipped with a front mounted 12" wide boom. Nozzles were wide angle flat fan delivering 0.2 gallons of spray solution per minute. Nozzle spacings were 18" on the boom and boom height was adjusted to be 12" above the soil or the tallest plants in the plots. Spray pressure was 28 p.s.i. and the propellent was compressed air.

Results and Discussion: All treatments provided 100% control of lambsquarters and giant ragweed. Figure 1 illustrates the control obtained from five of the treatments. The split application of Liberty (20.5 oz/acre applied at early and again at mid post) provided 100% control of all weeds in the study. The other post treatments also performed very well. Only the early post Liberty + Aatrex treatment and the Accent + Buctril/atrazine treatments provided giant foxtail control levels significantly lower than the split Liberty treatment.

With the exception of giant foxtail control, the standard Accent + Buctril/atrazine performed statistically equal to the split Liberty treatment. The standard Bicep treatment failed to provide the level of both broadleaf and grassy weed control that a producer would desire. Part of this could have been caused by the lack of adequate rainfall following application, and part of the reason was due to the heavy pressure of cocklebur and sunflower in the plots. It is not uncommon to need a post broadleaf application following Bicep in order to control large seeded broadleaf weeds.

In summary, all of the Liberty treatments provided out- standing weed control in this study. They performed equal to or better than the standard treatments in the study.

Figure 1