Rediscovering a Systems Approach to Weeds Management in Soybean

Transcription

1 Rediscovering a Systems Approach to Weeds Management in Soybean Tom Peters Extension Sugarbeet Agronomist North Dakota State University and the University of Minnesota

2 Remember when.. Scouted a field to identify weeds Use the Guide to determine effective tank-mixes for control of grasses, broadleaves and/or perennials weeds Would they carryover? Were they tank-mix compatible? Was there antagonism? Were they physically compatible? What about cost? Plan B.

3 Iowa, 1999

4 Herbicide quantities applied to corn and soybean,

5 Exponential Progression of Weeds Resistance 6,250,000 plants/a, year 3 Waterhemp escapes, year 1 2,500 plants/a, year 2

6 How do I identify resistant weeds? Weed escapes in what otherwise is a clean field Weed escapes might be a single plant or a group of plants Plants dead, injured and healthy in close proximity

7 Waterhemp has moved west, north and south from central Minnesota

8 Common Ragweed Kochia Growth habit, shallow, fibrous root system Germinates when soil temperatures between 50 and 80 F Germination at our near the soil surface More common with increase in soybean and dry bean acres Longevity, 25 to 35 years Resistant biotypes to multiple classes of herbicides ALS (SOA 2) PPO inhibitor (SOA 14) Glyphosate (9) Growth habit, 7 feet tall Biology, very deep rooted, tolerate saline soils Biology, extremely competitive; a few plants will reduce yield Loss of viability after one or two years Many document examples of herbicide resistance 2,4-D and MCPA (SOA 4) ALS (SOA 2) Glyphosate (SOA 9) Multiple resistance in ND, 2+4, 2+9, 2+4+9

9 New really isn t new A mixture of existing herbicide active ingredients Sometimes, product may actually contain a new active ingredient BUT Herbicide belongs to an existing herbicide mode of action family The last new mode of action launched in the corn and soybean market was the HPPD inhibitor (Callisto, Laudis) Late 1990s SOA group 27 There are no new herbicide modes of action available for 2016 or the foreseeable future We will have to make-do with the existing chemistries to manage weeds

10 We need to rediscover weed control

11 Traill County, ND, 2015

12 Weeds Management is a Strategy Identify problem weeds and develop a multi-year plan for their control Scout fields Positive identification of weeds Weed maps in fields Plan crop sequences in fields Carefully plan your choice of herbicides, herbicide families Observe and adjust

13 Pigweed Identification - No hairs on plant - Cotyledons egg-shaped - Long and narrow leaves - Leaves appear waxy - Smooth stems - Fine hairs throughout plant - First leaves rounded

14 How to Manage Herbicide-Resistant Weeds Scout fields; know how to identify weed resistance 11 known weed species in ND* 6 classes of herbicides - Wild oat - Green foxtail - Kochia - Wild mustard - Redroot pigweed - E black nightshade - Common ragweed - Marshelder - Waterhemp - Marestail - Lambsquarters - ACCase (1) - ALS inhibitors (2) - Mitotic inhibitors (3) - Growth regulators (4) - Photosystem II inhibitors (5) - EPSP synthase inhibitors (9) *additional information on weed resistance can be found in the North Dakota Weed Control Guide

15 Minimize "Deposits" and Maximize "Withdrawals Manage the seed bank it s a Numbers Game Photo from J Bond, Mississippi State Univ Single waterhemp plant in 2011 (Clay County, MN) estimate of the actual seed number per plant = 142,000

16 Weed seed survival in soil: Burnside et. al., Weed Sci: 44;74-85 Years of burial, Lincoln, NE Species % germination Green foxtail Common lambsquarters Kochia Redroot pigweed Waterhemp Russian thistle

17 Integrated Weed Management Cultural Mechanical Cultural Herbicide Herbicide Current Slide adapted from Bob Hartzler, Iowa State University Future

18 Mechanical weed control Tillage to control early flush of weeds Time tillage to crop planting to facilitate removal of first flush of weeds Mowing to prevent weeds from producing seed in non-cropped land, mow close and monitor for regrowth Row crop cultivation Hand-removal largest 10% may make 90% of seed Delay fall tillage to maximize weed seed predation Clean your equipment, especially in weedy fields

19 I am interested in your sugarbeet fields. I really am interested in your fields that will be planted to sugarbeet. Start clean Use full herbicide rates, effective tank-mixtures, and appropriate adjuvant Zero tolerance for weed escapes Manage field borders and ditches

20 Weed control in corn, Herman, MN and Moorhead, MN, 2015 Herman Moorhead Herman Moorhead Herbicide treatment 1 Appli Herbicide rate (pt, fl oz or oz/a) 9 Sept cheal 20 Aug cheal 9 Sept amata 20 Aug amata Harness + Clarity/ Laudis + atrazine Harness + atrazine / Status Sharpen / Status Sharpen / Status+ Warrant + RUPMax Laudis + atrazine / Status + RUPMax Pre / Post Pre / Post Pre / Post Pre / Post Post / Post 2 pt + 1 pt/ 3 oz + 12 oz 2 pt +12 oz / 7.5 oz 3 oz / 7.5 oz 3 oz / 5 oz + 3 pt + 28 oz 3 oz + 12 oz / 5 oz + 28 oz % control LSD (0.10) NS Laudis, atrazine and Status applied with MSO at 1.5 pt/a plus N-Pak AMS at 2.5% v/v; Roundup PowerMax, Status and Warrant applied with HSMOC at 1.5 pt/a plus N-Pak AMS at 2.5% v/v

21 Herman, MN, June 26, 2015

22 Verdict + Valor / Liberty S-metolachlor + Valor / Liberty July 16, 2015 Verdict / Basagran /Basagran Liberty / Liberty

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24 Weed control in soybean, Herman, MN and Moorhead, MN, 2015 Herman Moorhead Herman Moorhead Herbicide treatment 1 Application Herbicide rate (pt, fl oz or oz/a) 9 Sept cheal 20 Aug cheal 9 Sept amata 20 Aug amata S-metolachor + Valor / Liberty Verdict + Valor / Liberty Verdict / Basagran / Basagran Basagran + Cadet / Basagran + Cadet Pre/ Post Pre / Post Pre / Post / Post Post / Post 2 pt + 3 oz / 29 oz 5 oz + 3 oz / 29 oz 5 oz / 1 pt / 1 pt 0.5 pt oz / 0.5 pt oz % control Liberty / Liberty 2 Post / Post 29 oz / 29 oz LSD (0.10) NS NS Liberty applied with N-Pak ammonium sulfate at 3 lb/a; Cadet, and Basagran applied with MSO at 1.5 pt/a. 2 Experiment was planted to Liberty Tolerant soybean 3 Basagran, N-E; Cadet, P-G according to the 2016 ND Weed Control Guide

25 Herbicide Degradation Waterhemp biology Dual Magnum gives good waterhemp control when applied lay-by 1-Apr 10-Apr 20-Apr 30-Apr 1-May 10-May 20-May 30-May 1-Jun 10-Jun 20-Jun 30-Jun

26 Liberty and Liberty Tolerant Soybean complements residual herbicides The Liberty Link system with postemergence glufosinate (Liberty) can work well to forestall herbicide-resistant weeds One caution, if you use it like Roundup, it will not work Apply before weeds reach 3-inch height (or smaller) Apply with more water, Bayer says 15 gpa Apply with more AMS, Bayer says 3 lb/a Apply when environmental conditions are right You will break it if you abuse it

27 Factors contributing to a herbicide(s) decision Efficacious against weeds in your fields Know their crop rotational restrictions Changing herbicide SOA across crops Sprayer / tank cleanout Cost/A

28 Enlist or Xtend soybeans will be arriving soon How will the system perform on tough-to-control/ resistant weeds in YOUR FIELDS? 2,4-D dicamba Kochia N/P E Common ragweed E E Waterhemp F F/G Marestail E E Palmer amaranth N/P N/P Scale: - E = Excellent = 90 to 99% - G = Good = 80 to 90% - F = Fair = 65 to 80% - P = Poor = 40 to 65% - N = No Control A product of a conversation with Dr. Richard Zollinger, NDSU Weed Science

29 Roundup Ready Xtend Crop System Dicamba Tolerant Crops (Monsanto) Discovery at University of Nebraska of soil bacterium (Pseudomonas maltophilia) that metabolizes dicamba to a non-herbicidal/inactive form (Science 2007) Crop tolerance in transgenic plants achieved through insertion of a gene that encodes for a bacterial DMO (dicamba monooxygenase) enzyme (metabolism/deactivation gene) Production of DMO leads to breakdown of dicamba to the non-herbicidal 3,6-dichlorosalicylic acid Slide credit: Dr. Jim Griffin, Weed Scientist, LSU H 3,6-dichloro-o-anisic acid (dicamba acid) 3,6-dichlorosalicylic acid (non-herbicidal)

30 Concerns/Issues Dicamba and 2,4-D Technologies Labels will be very specific and restrictive Crop sensitivity 2,4-D on sugarbeet and dicamba on soybeans Like Brylcreem, a little dab ll do ya! These herbicides will tell on you! Off-target movement Volatility not likely to be major contributor; companies have developed low volatile formulations Physical drift affected by droplet size, spray pressure, nozzle type, boom height, wind speed, etc. Spray tank contamination/sprayer clean-out Slide credit: Dr. Jim Griffin,Weed Scientist, LSU

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32 In Summary Start clean Use full herbicide rates, effective tank-mixtures, and appropriate adjuvant Minimize weed escapes Manage field borders and ditches Make adjustments based on experience

33 Thank you for your Attention and your Support Tom Peters Extension Sugarbeet Agronomist and Weed Control Specialist Thomas (office) (mobile)