Objective: 

To evaluate the effects of herbicides and application rates on wild oat control and spring wheat yield.

Materials and Methods:

Twelve herbicides were applied to evaluate the consistency of wild oat control in spring wheat. The experimental design was a randomized complete block with three replications. Buckpronto hard red spring wheat was planted on a seven inch row spacing to a depth of two inches on April 15, at a rate of 120 lb/A. Wild oat was seeded in the center of each plot at a density of 30 seeds per square foot on April 17. Herbicide treatments were applied using a CO2 backpack sprayer with Teejet XR11002 nozzles in 20 GPA of water. Spring wheat and wild oat plants were at the 2-tiller and 3-leaf stage, respectively, at the time of application. Crop injury and wild oat control were both evaluated at one, three, and five weeks after application. Spring wheat yield and test weight were determined on July 31.

Results:

The greatest crop injury was initially observed with the tank mix of Varro, Widematch, and Affinity TankMix. Nevertheless, all injury symptoms diminished within five weeks of application, regardless of the treatment applied. Most treatments afforded excellent control of wild oat. The most complete control was observed with the tank mix of Varro, Olympus, and Carnivor. However, Wolverine Advanced and Goldsky plus MCPA failed to provide statistically equivalent control. Grain yields were low due to the drought conditions experienced during the growing season. As a result, yield differences were not observed among treatments, despite the wide range in wild oat control.

Summary:

Overall, Varro provided excellent control of wild oat, regardless of the tank mix partner. Wolverine Advanced and Goldsky do not appear to be well suited for wild oat control in this region of Montana.

Table 1. Materials and Methods - Spring Wheat Wild Oats - 2015.

Seeding Date: 4/17/2015 Harvest Date: 7/31/2015
Julian Date: 107 Julian Date: 212
Previous Crop: Canola Soil Type: Creston SiL
Tillage: Conventional Soil Test: 116-16-278
Irrigation:  None Fertilizer: 244-70-10, 6-30-20

Table 2: Herbicide Efficacy for Wild Oat Control in Spring Wheat, Kalispell, MT - 2015.

  % Crop Injury

 % Control Wild Oats

 Yield bu/A1 PRO %2 TWT1
Treatment 5/28 6/9 6/25 5/28 6/9 6/25  
Check 0.0 0.0 0.0 0.0 0.0 0.0 39.2 14.7 59.1
Varro
Bromac
Ammonium Sulfate		 6.9 oz/A
1.0 pt/A
0.5 lb/A		 10.0 13.3 0.0 61.7 90.0 96.0 46.4 14.6 59.0
Varro
Weld Herbicide
Ammonium Sulfate		 6.9 oz/A
1.3 pt/A
0.5 lb/A		 26.7 20.0 0.0 68.3 93.3 98.3 41.4 14.9 59.3
Varro
Carnivore Herbicide
Ammonium Sulfate		 6.9 oz/A
1.0 pt/A
0.5 lb/A		 16.7 11.7 0.0 73.3 85.0 96.3 48.3 14.7 59.1
Varro
Widematch
2, 4-D Ester
Ammonium Sulfate		 6.9 oz/A
1.0 pt/A
0.5 pt/A
0.5 lb/A		 11.7 15.0 0.0 70.0 91.7 89.3 41.9 14.9 59.2
Varro
Widematch
MCPA Ester
Ammonium Sulfate		 6.9 oz/A
1.0 pt/A
0.5 pt/A
0.5 pt/A		 20.0 20.0 0.0 68.3 83.3 96.7 41.4 14.9 59.7
Varro
Widematch
Affinity Tank Mix
Ammonium Sulfate		 6.9 oz/A
1.0 pt/A
0.6 oz/A
0.5 lb/A		 30.0 18.3 0.0 55.0 93.3 98.0 37.1 15.2 58.8
Varro
Olympus
Carnivore Herbicide
Ammonium Sulfate		 6.9 oz/A
0.2 oz/A
1.0 pt/A
0.5 lb/A		 23.3 15.0 0.0 66.7 81.7 99.0 45.1 15.0 59.3
Huskie Complete
Ammonium Sulfate		 13.7 oz/A
0.5 lb/A		 21.7 18.3 0.0 60.0 93.3 96.0 42.8 14.8 59.0
Wolverine Advanced 27.4 oz/A 3.3 16.7 0.0 46.7 78.3 79.9 41.7 14.6 59.0
Everest 2.0
Supremacy
NIS		 0.8 oz/A
4.5 oz/A
0.3% v/v		 6.7 15.0 0.0 60.0 90.0 95.0 41.7 14.7 59.3
Goldsky
MCPA Ester		 1.0 pt/A
0.5 pt/A		 13.3 16.7 0.0 63.3 86.7 80.0 44.5 14.4 59.4
Axial XL
Huskie		 16.4 oz/A
13.5 oz/A		 6.7 10.0 0.0 56.7 81.7 97.3 44.9 14.4 59.2
Mean 14.6 14.6 0.0 57.7 80.6 86.3 42.8 14.7 59.2
CV 42.3 40.0 0.0 25.3 12.2 8.1 9.5 1.2 0.6
LSD 10.4 9.9 ns 24.6 16.6 11.8 ns 0.3 ns
Pr>F 0.0001 0.0277 1.000 0.0004 0.0001 0.0001 0.1400 0.0002 0.3579

PRO: protein; TWT: test weight

1 adjusted to 13% moisture

2 adjusted to 12% moisture