Broadleaf Weed Control in Spring Wheat

Charles E. Stanger and Joey Ishida

Malheur Experiment Station
Oregon State University
Ontario, Oregon, 1995
 

Purpose

In two separate trials, 13 different herbicides and formulations were evaluated for weed control and tolerance to spring wheat when applied at different rates in tank-mix combinations.


Materials and Methods

Treasure variety of spring wheat and kochia (Kochia scoparia) weed seed were planted on April 3, 1995, in a field where potatoes had been grown during 1994. Herbicides applied to control weeds in potatoes included Prowl, Eptam, Matrix and Poast. Herbicide rates for potatoes were 1.5, 3.0, 0.028 and 0.3 lb ai/ac, respectively. The potatoes had been irrigated by sprinkler irrigation. The field was not plowed after potatoes but left over-winter to freeze leftover tubers and tilled with a triple-K field cultivator and ground-hog field cultivator in the spring before planting the wheat. Seeding rate of wheat was 130 lb/ac planted with a double-disc drill with 6-inch row spacing. The field was harrowed and corrugated after planting in preparation for furrow irrigation. One hundred lbs/ac nitrogen was applied broadcast and tilled in the soil as the seedbed was prepared. Soil texture was a silt loam with a pH of 7.3 and 1.1 percent organic matter.

Herbicide treatments were applied on May 18. The wheat had two to three tillers and was 6 to 8 inches tall. Weed populations were dense, and species included kochia, lambsquarters, redroot pigweed, tumble mustard, hairy nightshade, and annual sow thistle. Weed species varied from 1 to 6 inches tall. The tallest species was kochia. Tumble mustard and sowthistle had 2 to 3-inch rosettes. At application, the wind was blowing 2 to 3 mph from the northwest. Air temperature was 78°F, and soil temperature at 4-inches deep was 72o F. Relative humidity was 38 percent with clear skies.

Herbicides were applied with a single bicycle-wheel plot sprayer. The spray boom was 8.5 feet long. Teejet fan nozzles size 8002 were spaced 10-inches apart on the spray boom, and herbicides were applied broadcast as double-overlap applications. Spray pressure was 42 psi, and water as the herbicide carrier was applied at a volume of 33.4 gal/ac. Individual plots were 9 feet wide and 40 feet long, and each treatment was replicated three times in blocks using a randomized complete block experimental design.

The plots were harvested on August 22 and 23 to determine grain yields. Harvest area was 4 feet wide x 35 feet long. Grain yields are reported as bushels per acre of clean wheat.


Results

All herbicide treatments, with the exception of Peak, controlled all weed species (Tables 1 and 3). Peak controlled about 90 percent of kochia, lambsquarters, and redroot pigweed and about 82 percent control of hairy nightshade and 63 percent control of annual sow thistle. The highest wheat yields occurred when weeds were fully controlled with herbicides. Weed competition in the untreated checks reduced wheat yields significantly (Tables 2 and 4). Kochia was very vigorous and grew 3 to 4 feet above the height of the wheat in the untreated checks. Tough, a herbicide, in tank-mix combination with Sencor caused severe necrosis to the leaves of the wheat. The wheat plants recovered from the foliar injury, but wheat yields were significantly less compared to yields from other treatments.

Table 1. Crop injury ratings and percent weed control from herbicide treatments applied to Treasure spring wheat. Malheur Experiment Station, Oregon State University, Ontario, Oregon, 1995.
  Percent weed control
  Crop injury  Kochia Lambsquarters Pigweed Tumble mustard H. nightshade Sowthistle
Herbicides Rate 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
  lb ai/ac  %   % 
Peak + X-77 0.018 + 0.25% 0 0 0 93 90 90 85 90 85 95 95 95 90 95 90 85 80 80 65 60 60
Bronate Gel 0.5 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Bronate 0.5 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Bronate 0.8 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Harmony Extra + X-77 0.016 + 0.25 % 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Bronate Gel + Harmony Extra + X-77 0.5 + 0.016 + 0.25% 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Bronate + Harmony Extra + X-77 0.5 + 0.016 + 0.25 % 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
MCPA Ester + Harmony Extra + X-77 0.25 + 0.016 + 0.25 % 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Weedar 64 + Harmony Extra + X-77 0.25 +0.016 + 0.25 % 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Banvel SGF + Harmony Extra + X-77 0.25 + 0.016 + 0.25 % 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Bronate + Express + X-77 0.5 + 0.004 + 0.25 % 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Bronate 1. 0 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Weedar 64 1. 0 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Harmony Extra + X-77 0.0234 + 0.25 % 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Harmony Extra + Weedar 64 + X-77 0.0234 + 0.5 + 0.25 % 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Bronate + Harmony Extra + X-77  0.25 + 0.0234 + 0.25 % 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Untreated Check -- 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Evaluated on May 30 and June 6. Ratings on the two dates were the same.
Ratings: 0 = No herbicide effect. 100 = all plants killed.

Table 2. Grain yields of Treasure spring wheat treated with herbicides applied postemergence for control. Malheur Experiment Station, Oregon State University, Ontario, Oregon, 1995.
  Yield
Herbicides Rate R1 R2 R3 Mean
  lb ai/ac  bu/ac 
Peak + X-77 0.018 + 0.25% 96 99 101 98. 7
Bronate Gel 0.5 102 105 100 102. 3 
Bronate 0.5 106 102 104 104. 0
Bronate 0.8 104 101 107 104. 0
Harmony Extra + X-77 0.016 + 0.25% 101 103 105 103. 0
Bronate Gel + Harmony Extra + X-77 0.5 + 0.016 + 0.25% 105 100 103 102. 7
Bronate + Harmony Extra + X-77 0.5 + 0.016 + 0.25% 103 106 105 104. 7
MCPA ester + Harmony Extra + X-77 0.25 + 0.016 + 0.25% 101 104 98 101. 0
Weedar 64 + Harmony Extra + X-77 0.25 + 0.016 + 0.25% 99 103 96 99. 3
Banvel SGF + Harmony Extra + X-77 0.25 + 0.016 + 0.25% 98 100 97 98. 3
Bronate + Express + X-77 0.5 + 0.004 + 0.25% 104 101 99 101. 3 
Bronate 1. 0 102 104 106 104. 0
Weedar 1. 0 101 98 104 101. 0
Harmony Extra + X-77 0.0 2 103 105 99 102. 3
Harmony Extra + X-77 Harmony Extra + Weedar 64 + X-77 0.0234 + 0.5 + 0.25% 99 103 101 101. 0
Bronate + Harmony Extra + X-77 0.25 + 0.0234 + 0.25% 104 106 103 104. 3
Untreated Check -- 81 88 93 87. 3
LSD (0.05) 5. 0
CV (%) 3. 0
Mean 101. 3 
Harvested August 22, 1995.

Table 3. Crop injury and percent weed control from herbicide treatments applied to Treasure spring wheat. Malheur Experiment Station, Oregon State University, Ontario, Oregon, 1995.
  Percent weed control
  Crop injury Kochia Lambsquarters Pigweed Tumble mustard H. nightshade
Herbicides Rate 1 2 3 1 2 3 1 2 1 2 3 1 2 3 1 2 3
  lb ai/ac  %
Banvel + Buctril 0.094 + 0.25 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Banvel + Buctril + MCPA amine 0.094 + 0.125 + 0.25 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Banvel + Buctril + MCPA amine 0.094 + 0.025 + 0.25 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Banvel + Buctril + Harmony Extra 0.094 + 0.125 + 0.0078  0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Banvel + Buctril + Harmony Extra 0.094 + 0.25 + 0.0078 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Buctril + Harmony Extra 0.125 + 0.0078  0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Banvel + Buctril + MCPA amine 0.094 + 0.125 + 0.25 + 0.0078  0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Tough (ec) 0.9 40 30 40 85 90 85 90 90 85 90 95 95 75 80 75 95 90 95
Tough (ec) 0.5 20 25 15 75 80 80 80 85 80 90 80 80 65 70 70 85 80 80
Banvel + Tough (ec) 0.094 + 0.47 30 30 40 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Banvel + Weedar 64 0.094 + 0.38 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Banvel + Weedar 64 + Tough (ec) 0.094 + 0.38 + 0.235 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Tough (ec) + Sencor 0.47 + 0.125 45 50 45 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Banvel + Weedar 64 + Harmony Extra 0.094 + 0.25 + 0.0078 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Banvel + Weedar 64 + Harmony Extra 0.094 + 0.25 + 0.0156 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Banvel + Weedar 64 + Tough (ec) 0.094 + 0.25 + 0.47 10 10 15 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Banvel + Weedar 64 + Buctril 0.094 + 0.25 +0.25  0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
San 845H + Weedar 64 0.094 + 0.38 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
San 845H + Savage 0.094 + 0.38 0 0 0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
Untreated Check -- 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Banvel formulated 45L was used in all Banvel treatments.
X-77 was added to all herbicide treatments at the rate of 0.25 % v/v.
Evaluated on May 30 and June 6. On June 6 the wheat plants were recovering from the Tough and Tough combination treatments.
Ratings: 0 = No herbicide effect. 100 = all plants killed.

Table 4. Grain yields in bushels per acre from herbicide treatments applied to Treasure spring wheat. Malheur Experiment Station, Oregon State University, Ontario, Oregon, 1995.
  Yield
Herbicides Rate R1 R2 R3 Mean
  lb ai/ac  bu/ac
Banvel + Buctril 0.094 + 0.25 98 102 99 99. 7
Banvel + Buctril + MCPA amine 0.094 + 0.125 + 0.25 101 98 96 98. 3
Banvel + Buctril + MCPA amine 0.094 + 0.25 + 0.25 98 100 102 100. 0 
Banvel + Buctril + Harmony Extra 0.094 + 0.125 + 0.0078 104 102 99 101. 7 
Banvel + Buctril + Harmony Extra 0.094 + 0.25 + 0.0078 103 101 104 102. 7 
Buctril + Harmony Extra 0.125 + 0.0078 106 103 101 103. 3 
Banvel + Buctril + MCPA amine + Harmony Extra 0.094 + 0.125 + 0.0078  103 99 102 101. 3 
Tough (ec) 0.9 101 105 99 101. 7 
Tough (ec) 0.5 99 103 98 100. 0 
Banvel + Tough (ec) 0.094 + 0.47 102 99 101 100. 7 
Banvel + Weedar 64 0.094 + 0.38 103 98 99 100. 0 
Banvel + Weedar 64 + Tough 0.094 + 0.38 + 0.235 102 104 98 101. 3 
Tough (ec) + Sencor 0.47 + 0.125 96 94 97 95. 6 
Banvel + Weedar 64 + Harmony Extra 0.094 + 0.25 + 0.0078 102 104 98 101. 3
Banvel + Weedar 64 + Harmony Extra 0.094 + 0.25 + 0.0156 103 99 101 101. 0
Banvel + Weedar 64 + Tough 0.94 + 0.25 + 0.47 104 102 103 103. 0
Banvel + Weedar 64 + Buctril 0.094 + 0.25 + 0.25 101 104 99 101. 3
San 845 H + Weedar 64  0.094 + 0.38 103 99 101 101. 0
San 845 H + Savage 0.094 + 0.38 104 101 98 101. 0
Untreated check -- 83 85 80 82. 7
LSD (0.05) 3. 6
CV (%) 2. 2
Mean 99. 8
Harvested August 23, 1995.