NDSU Crop and Pest Report
Weeds


ISSUE 5  May 29, 2003

 

VOLUNTEER BARLEY CONTROL HRS WHEAT

A question was asked which POST wild oat herbicide will do the best job in controlling volunteer barley in HRS wheat. A study was done in 2001 (Page 9, Green section of 2001 ND Weed Control Research) where different POST wild oat herbicides were applied at full label rates to barley. Everest and Discover each caused 65% injury in the form of stunting and yellowing which lasted most of the season. Maturity was delayed by more than one week and there was a low to moderate occurrence of deformed heads. However, at harvest barley treated with full label rates of Discover and Everest yielded 65% of the untreated plots (untreated yielded 70 bu/A, Discover yielded 49 bu/A and Everest yielded 48 bu/A).

If the volunteer barley population is low and the HRS wheat crop is dense, growing well, and exerting strong and aggressive competition, perhaps greater barley suppression/ control might occur. That’s what the data shows.

 

KOCHIA CONTROL FROM BASAGRAN (bentazon)

A question was asked why does the NDSU Weed Guide show such a low rating (Poor) for kochia from Basagran (benazon) when some growers have seen better, even G-E kochia control. Glyphosate in Roundup Ready Soybean and registration of Raptor and Pursuit have taken most of the Basagran market away in soybean. Basagran, especially in the Rezult formulation, is used in drybeans and dry pea.

In the weed guide "P" is defined as 40% to 60% control. It appears that some believe Basagran gives higher kochia control. Lets look at the herbicide. Basagran is inherently weak on weeds normally found in ND fields, such as, redroot pigweed, common lambsquarters, wild buckwheat, E black nightshade, and common ragweed. The maximum labeled rate of 2 pt/A is required for these moderately sensitive weeds but Basagran at 1 to 2 pt/A costs ~ $10 to $20/A, so growers would normally use 1 pt/A or less to save money. Growers may add another product with Basagran or choose an entirely different product if available for full-spectrum broadleaf weed control. The low price of Rezult is certainly an incentive to buy Basagran in that co-pack. Basagran is a contact herbicide so weed control decreases as weed size increases. Basagran is strongly affected by sunlight and temperature - the more sun and higher the temperature the better the activity, as long as plants are actively growing. Adjuvants affect Basagran and the highest activity occurs when oil adjuvants are used with Basagran.

Now to highlight ‘WeedIT’. WeedIT is a computer program that includes a database of all NDSU weed control data printed in the North Dakota Weed Control Research books. All NDSU weed scientists and experiment station staff contribute to the yearly publication. The program is in development and has weed control data from 1979 to 2002 and data as far back as 1970 is currently being entering.

A search was done in WeedIT for all observations of Basagran on kochia. A total of 970 observations were found. I deleted all treatments that included another broadleaf herbicide and those with rates lower than 3/4 pt (except treatments of sequential micro-rate Basagran). After deleting those treatments the total was 150 different evaluations and kochia control ranged from 1% to 99%. The average of 105 single applications of Basagran gave 64.4% kochia control. The average of two sequential applications of Basagran applied at 0.5 to 0.75 pt/A at each application was 87.8% control. The average of three sequential applications of Basagran applied at 0.33 pt/A at each application was 89.4% control. The average of four sequential applications of Basagran applied at 0.2 pt/A at each application was 92% control.

Obviously, multiple (even two) applications of Basagran greatly improved kochia control. NDSU research also show that multiple applications improve control of the moderately susceptible weeds listed earlier. Other things observed from perusing the data was that oil adjuvants gave greater kochia control than NIS + UAN, 1 pt/A rates gave greater kochia control lower rates, and the smaller the weeds the greater the control. So according to the NDSU data base, the 64% kochia control from one Basagran application approaches the range of "Poor" defined in the guide. Perhaps we should change the rating to "Poor-Fair" in the next edition to be more accurate. "Fair" is defined as 65% to 80% control.

This is just a small example of how WeedIT can be used and the potential to strengthen weed control ratings. More to come about WeedIT in future Pest Report articles.

 

HERBICIDE UPDATE - PART 2

AgValue

AgValue company has labeled clopyralid and ethofumesate in ND on the same crops that the federal Stinger and Nortron labels indicate. These would include sugarbeet.

Dual Magnum (Syngenta)

Mode of action: Long chain fatty acid inhibitor

a.i.: s-metolachlor

Crops: Sunflower and sugarbeet

Comments: New registration in crops listed above. Apply 1 to 2 pt/A based on organic matter and soil type.

Pursuit (BASF)

Mode of action: ALS inhibitor

a.i.: imazethapyr

Crops: Dry beans, dry pea, chickpea, and lentil

Comments: ND label allows PPI or PRE application in crops listed above at 0.72 oz/A. Use of Pursuit PPI or PRE restricts use of the herbicide POST.

Reflex (Syngenta)

Mode of action: PPO inhibitor

a.i.: fomesafen

Crops: Dry bean

Comments: ND Section 18 registration has been approved allowing Reflex to be used on dry beans for broadleaf weed control, including waterhemp, common ragweed, and eastern black nightshade. See ND Weed Control Guide for rates and uses. Geographic area that Reflex can be used has been increased in 2003 and now includes all the following counties: Barnes, Benson, Bottineau, Burleigh, Cass, Cavalier, Dickey, Eddy, Foster, Grand Forks, Griggs, Kidder, LaMoure, McLean, Nelson, Oliver, Pembina, Pierce, Ramsey, Ransom, Richland, Sargent, Steele, Stutsman, Towner, Traill, Walsh, and Wells counties. Apply at 0.75/A to weeds 1 to 4 inches tall with petroleum oil adjuvant at 0.5 to 1% v/v. Apply prior to dry bean bloom and before 30 days of harvest.

TENKOZ

Tenkoz, the parent company of Rosens, will market herbicides in ND. They are:

Volley - (acetochlor + safener) equivalent to Harness/Surpass

Volley ATZ - acetochlor + atrazine

Blanket - (sulfentrazone) equivalent to Authority on soybean

Priority - premix of Aim + Permit on corn

Richard Zollinger
NDSU Extension Weed Specialist
rzolling@ndsuext.nodak.edu


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