The 47th annual survey of weed control and production practices among sugarbeet growers in Minnesota and eastern North Dakota received electronically submitted responses from 90 growers — down substantially from the 188 who responded to the prior year’s survey questionnaire. Growers in the region planted just under 639,000 acres of beets in 2015, with the respondents representing 58,776 acres, or 9% of the total acres (compared to 16% for the 2014 survey).
Of the acres reported upon, 100% were planted to Roundup Ready® sugarbeet varieties (compared to 99% the previous year). Total beet acreage treated with herbicides (taking into account multiple applications) was 260% — compared to 2014’s 236%. (By comparison, the corresponding numbers for 2006 and 2007 — the two years just prior to the introduction of Roundup Ready (RR) beets — were 386% and 383%, respectively.)
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Nortron, Dual Magnum and tank mixes of Nortron + Dual were the soil applied herbicides used by respondents in 2015. Soil-applied herbicide use for all reported acreage was at 18% last year. That compares with 4% in 2014, 3% in 2013 and 2% in 2012.
Lay-by herbicides Outlook, Warrant and Dual Magnum were applied to 42% of reported acres in 2015, compared to 15% the previous year. “The increase in lay-by applications from 2014 to 2015 is likely due to the increasing presence of glyphosate-resistant waterhemp,” state the survey report authors*. “All lay-by applications were made as tank mixes with glyphosate and/or other herbicides.” Outlook was the most commonly used lay-by product.
The most common herbicide treatment reported by all survey respondents since 2009 has been glyphosate applied post emergence. Alone and when combined across all tank-mix combinations, the glyphosate post treatment was applied to 242% of all 2014 acreage reported upon. That number in 2014 was 227%; in 2013 it was 215%; in 2012, 192%. Glyphosate + Stinger (37% of acres treated) and glyphosate + Outlook (16%) were the most frequently reported herbicide combinations by respondents planting beets in 2015. Stinger helps control weeds like common ragweed or volunteer RR soybeans, whereas Outlook can be added as a lay-by to control small seeded broadleaves like waterhemp.
“The Roundup Ready sugarbeet system continues to provide the most effective post weed control reported by growers in the history of this survey,” the authors state. Of the respondents to the 2015 survey, 41% reported excellent post weed control. “Of those growers who reported weed control from glyphosate applied alone (excludes those who did not respond), 60% reported excellent weed control in 2015, compared to 63% in 2014, 75% in 2013, 77% in 2012, 80% in 2011, 81% in 2010, 87% in 2009 and 92% in 2008,” they continue, adding that the declining trend “of excellent weed control by respondents with RR sugarbeet should be noted as it is likely an indicator of increasing levels of glyphosate-resistant weeds.”
* Report authors were Andrew Lueck, sugarbeet research specialist, North Dakota State University and the University of Minnesota; Tom Peters, extension sugarbeet specialist, NDSU/UM; Mohamed Khan, extension sugarbeet specialist, NDSU/UM; and Mark Boetel, professor of entomology, NDSU.
Waterhemp was reported most frequently as the “worst weed” problem by 46% of respondents planting RR beets in 2015. Each year from 2008 to 2013, “none” was chosen most often for the “worst weed” designation. The takeaway message, the survey coordinators state, is that “growers should closely monitor their farms for waterhemp escapes and create management strategies that do not rely upon glyphosate alone.” Ragweed (14%), “None” (10%) and common lambsquarters (10%) were the next most reported “worst weed” problems by 2015 survey respondents. Nearly one-fourth — 22% — of survey respondents indicated they plan to use a soil-applied (PPI or PRE) herbicide in the spring of 2016. Another 41% said they do not plan to do so, while 37% were still undecided as of the time they filled out the survey. When asked if they planned to use a lay-by herbicide this coming season, 36% said yes, 34% said no, and 30% said “maybe.”
Here are a few more highlights from the 2015 survey report:
• Averaged across all counties, hand weeding was reported on 13% of beet acres last year. Renville, Chippewa and Norman counties in Minnesota and Richland and Cass counties in North Dakota each reported more than 10% hand-weeded acreage. A substantial percentage of reporting growers in four of these counties (Renville, Chippewa, Richland and Cass) gave high “worst weed” ratings to waterhemp, which likely is related to their higher use of hand weeding.
• Once again, Rhizoctonia/Aphanomyces was selected most often — 45% — by survey respondents as the “most serious production problem.” From 1999 through 2008, weeds were deemed the primary problem; but only 14% of respondents indicated so in 2015 (up from 7% in 2014). “Emergence/ stand”-related issues were indicated as the worst production problem in 2015 by 18% of respondents. Last spring was very dry in much of the region, allowing for early planting.
• Cover crops were seeded on 49% of respondents’ beet acreage in 2015. Barley (25%) was the most commonly reported cover crop. Respondents from Chippewa County, Minn., and Richland County, N.D., reported the highest rate of cover crop seeding at 80% and 84%, respectively, of beet acres.
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