Consider herbicide selectivity and carryover if you want successful fall cover crops

Transcription

1 Consider herbicide selectivity and carryover if you want successful fall cover crops Bill Curran, Penn State University

2 Diverse Crop Rotations Can Provide Many Benefits and Cover Crops Can Be Part of This Diversity can provide Additional sources of feed or forage Improved nutrient cycling Opportunities to cover the soil and improvements in soil quality Integrated pest management and other ecosystems services Economic stability or greater market opportunities But Greater complexity requires more management Herbicide selection and rotation flexibility are an important consideration in diverse rotations Crop Management 1+1 Webinar

3 Cover crops can be a valuable part of the cropping system Crop Management 1+1 Webinar Hairy Vetch Cereal Rye Oats Red Clover Forage Radish Winter Wheat

4 Residual Herbicides Used in many of our major crops Usually soil applied not always Generally provide 8 to 12 weeks of weed control Half life too short lack of residual weed control (performance reduced) Half life too long carryover to following crop Very important consideration for some crops and especially those established in late summer

5 Herbicide carryover to wheat

6 Carryover Injury to Subsequent Crops Depends On: Herbicide persistence in soil How long does it last? Herbicide half life gives us some indication Rotational crop susceptibility How sensitive are rotational crops legumes, other broadleaves, grasses As long as cover crops are not harvested for animal consumption (but they often are), illegal residues not a concern, but injury risk remains with the grower

7 Dissipation or Degradation rate Half-life: the amount of time needed to degrade half of the herbicide present

8 Herbicide half life Short < 30 days Intermediate days Long > 120 days

9 Herbicide carryover potential based on half lives and soil availability Herbicide Strengths Half life (days) Carryover potential 2,4 D amine broadleaves 7 None Accent brdlfs+grass 21 Low Assure/Targa grass 60 Low Atrazine brdlfs+grass 60 Moderate Authority broadleaves Moderate Balance Pro brdlfs+grass Moderate Callisto broadleaves 5 32 Moderate Clarity/Banvel broadleaves 5 14 None Classic broadleaves 40 Moderate Dual II Mag brdlfs+grass Low FirstRate broadleaves 8 33 Low Glyphosate brdlfs+grass 47 None Gramoxone brdlfs+grass 1000 None Harmony broadleaves 12 Low Harness brdlfs+grass Low Ignite brdlfs+grass 7 None Impact brdlfs+grass 14 Low Laudis brdlfs+grass 14 Low Outlook brdlfs+grass 20 Low Peak broadleaves Moderate Permit broadleaves 9 27 Low Prowl H2O brdlfs+grass 44 Low Pursuit brdlfs+grass Moderate Raptor brdlfs+grass Low Reflex broadleaves 100 Moderate Resolve brdlfs+grass 2 4 Low Select grass 3 d None Sencor brdlfs+grass Low Sharpen broadleaves 7 35 Low Simazine brdlfs+grass 60 d Moderate Stinger broadleaves 40 Moderate Valor broadleaves low Herbicide half life estimates derived from the WSSA Herbicide Handbook, 2007 or other scientific literature.

10 Herbicide carryover potential based on half lives and soil availability Herbicide Strengths Half life (days) Carryover potential 2,4 D amine broadleaves 7 None Accent brdlfs+grass 21 Low Assure/Targa grass 60 Low Atrazine brdlfs+grass 60 Moderate Herbicide Strengths Half life (days) Carryover potential 2,4 D amine broadleaves 7 None Authority broadleaves Moderate Balance Pro brdlfs+grass Moderate Atrazine Callisto broadleaves brdlfs+grass Moderate Moderate Clarity/Banvel broadleaves 5 14 None Classic broadleaves 40 Moderate Dual II Mag brdlfs+grass Low Dual II Mag brdlfs+grass Low FirstRate broadleaves 8 33 Low Glyphosate brdlfs+grass 47 None Gramoxone brdlfs+grass 1000 None Harmony broadleaves 12 Low Harness brdlfs+grass Low Ignite brdlfs+grass 7 None Impact brdlfs+grass 14 Low Laudis brdlfs+grass 14 Low Outlook brdlfs+grass 20 Low Peak broadleaves Moderate Permit broadleaves 9 27 Low Prowl H2O brdlfs+grass 44 Low Pursuit brdlfs+grass Moderate Raptor brdlfs+grass Low Reflex broadleaves 100 Moderate Resolve brdlfs+grass 2 4 Low Select grass 3 d None Sencor brdlfs+grass Low Sharpen broadleaves 7 35 Low Simazine brdlfs+grass 60 d Moderate Stinger broadleaves 40 Moderate Valor broadleaves low Glyphosate brdlfs+grass 47 None Herbicide half life estimates derived from the WSSA Herbicide Handbook, 2007 or other scientific literature.

11 Recrop Restriction Information Current Herbicide Labels University Agronomy Guides University Commercial Vegetable Production Recommendations (extension.psu.edu/vegetablefruit/production guides/2011 comercial)

12 Penn State Agronomy Guide Table Example corn herbicide rotational restrictions (months after application). Herbicide Alfalfa Clover Grain sorghum Soybeans Spring Oats Winter Barley Winter rye Winter Wheat Longest Accent Atrazine SY SY NR NY SY NY NY NY SY Balance Callisto NR 10 NR Dual 4 9 NR NR Hornet Permit SY Prowl NY NY NY NR NY 4 NY 4 NY Sharpen 1 oz 4 4 NR 0 NR NR NR NR 4 *Lumax NY NY NY NY * Mixture of Atrazine + Callisto + Dual

13 Recrop Interval Information Determine which products have 4 month rotation restriction for potential rotation crops or their relatives. Alfalfa, clover, pea, sorghum, oats, wheat, barley, and are included in the PSU Agronomy Guide. Hairy vetch and more obscure legumes are not listed. Examine alfalfa or clover restrictions to get a good idea of which herbicides may cause potential injury to other legumes. Crops such as canola, forage radish, and buckwheat can be difficult to determine as they are usually never listed. Small seeded species generally most sensitive.

14 Corn herbicides General guidelines In general, atrazine or simazine applied PRE at less than 1 lb/a can allow cereal grain establishment; less than 0.75 lb/a may allow for most legume cover crops, mustards, and annual ryegrass. Mesotrione (Callisto and a component of Lumax/Lexar, Halex GT and others) is problematic for legumes and mustards like canola and forage radish. Additional products containing this active are forthcoming. Clopyralid (Stinger and a component of Hornet and SureStart) could also affect these small seeded broadleaves. Soybean herbicides Chlorimuron (Canopy, Classic, Envive, Synchrony, etc.), Pursuit or Extreme (imazethapyr), and Prefix or Reflex/Flexstar (fomesafen) could be a problem for fall seeded legume or mustard cover crops, but cereal grains should be OK.

15 General guidelines (cont.) Other corn and soybean herbicides and their impact on legumes or mustard species in particular is less clear. Wheat herbicides Generally not a problem, except for companion or relay cropping If you can double crop soybean, should be OK Until more research is conducted assessing specific herbicide cover crop interactions, the general guidelines provided in Agronomy Guide Tables and can be helpful.

16 Corn Herbicide Safety Study 2010 & 2011 Silt loam soils, 1 3% OM, ph = 6.5, precip. = 45 in Herbicide treatments 25 to 27 corn herbicides applied pre and some post Cover crop treatments planted at inter seeding (after POST) and after silage harvest Visual evaluation in fall and spring (0 100% scale) Fall seeded Inter seeder Inter seeder ryegrass, red and white clover, and mixture Fall rye, wheat, oats, ryegrass, clovers, hairy vetch, canola, forage radish

17 Results Had a number of challenges slugs, compaction, drought, too many plots ( ) Clovers, forage radish, and canola data mostly lost and hairy vetch variable Inter seeder metolachlor, nicosulfuron, (atrazine?) reduced ryegrass Fall did not observe problems for establishment of cereals oats, wheat, and rye Concerned about translating results to the farming public (small inference space) need more locations and years to be confident Other ways to study or demonstrate this more easily?

18 Effect of PRE herbicides on annual ryegrass establishment with inter seeder (2010) Treatment Rate (lb ai/acre) % Reduction Untreated Atrazine Atrazine Atrazine Simazine Simazine Mesotrione (Callisto) Isoxaflutole (Balance) Flumetsulam (Python) Rimsulfuron (Resolve) Clopyralid (Stinger) Saflufenacil (Sharpen) Pendimethalin (Prowl) s metolachlor (Dual) Isoxaflutole + Atrazine Mesotrione + Atrazine LSD (0.05) Crop Management 1+1 Webinar

19 Effect of PRE herbicides on annual ryegrass establishment with inter seeder (2010) Treatment Rate (lb ai/acre) % Reduction Untreated Atrazine Atrazine Atrazine Simazine Simazine Mesotrione (Callisto) Isoxaflutole (Balance) Flumetsulam (Python) Rimsulfuron (Resolve) Clopyralid (Stinger) Saflufenacil (Sharpen) Pendimethalin (Prowl) s metolachlor (Dual) Isoxaflutole + Atrazine Mesotrione + Atrazine LSD (0.05) Crop Management 1+1 Webinar

20 Callisto (mesotrione) injury on fall seeded forage radish Dual (metolachlor) injury on inter seeded ryegrass

21 Predicting Herbicide Half Life If it s short, it s always short, but For intermediate or long, it can be a moving target Factors: Application timing, rate, and frequency Dry vs. wet weather Soil clay and organic matter content and soil ph Heavy soils more problematic High and low ph more problematic (<5 and >7) Herbicide history Just because you get away with it once, doesn t mean you won t have a problem another time Half life doesn t demonstrate selectivity/susceptibility

22 Herbicide persistence and selectivity demonstration 1 & 2 L bottles Weed Systems (weedsystems.com) Seeded crimson clover, alfalfa, annual ryegrass, forage radish, sorghum sudangrass, hairy vetch, oats, and cereal rye and applied herbicides PRE (18 different treatments) using a log sprayer

23 Herbicides included in Demo Trt Treatment Form Form Rate Other Other Estimated No. Name Conc. Type Rate Unit Rate Rate Unit Half life 1 1. Untreated 2. Dual II Magnum 7.62 EC 1.59 lb ai/a 1.67 pt/a (35) 3. Harness 7 EC 1.75 lb ai/a 2 pt/a (15) 4. Prowl H2O 3.8 CS 1.42 lb ai/a 3 pt/a Atrazine 4 L 1.5 lb ai/a 3 pt/a Callisto 4 SC lb ai/a 6 fl oz/a Classic 25 DF lb ai/a 2 oz/a Valor 51 WDG 0.08 lb ai/a 2.5 oz/a (16) 9. Pursuit 70 DG lb ai/a 1.44 oz/a (75) 10. Raptor 1 SC lb ai/a 5 fl oz/a (25) 11. Resolve 25 DF lb ai/a 1 oz/a 2 4 (3) 12. Sharpen 2.85 SC lb ai/a 3 fl oz/a 7 35 (21) 13. Bicep II Mag 5.5 L 2.9 lb ai/a 2.1 qt/a Lumax 3.95 L 2.47 lb ai/a 2.5 qt/a Callisto 4 SC lb ai/a 3 fl oz/a 5 32 (20) Atrazine 4 L 0.75 lb ai/a 1.5 pt/a Impact 2.8 SC lb ai/a.75 fl oz/a Permit 75 DF lb ai/a.66 oz/a 9 27 (18) 18. Accent 75 DF lb ai/a.66 oz/a 21

24 Herbicide Demo Half life Rate reduction Tradename Rate/A Common name 1X 1/2X 1/4X 1/8X 1/16X lb ai/acre and days to reach rate 1. Dual II Magnum 1.67 pt metolachlor Atrazine 4L 3 pt atrazine Callisto 4SC 6 oz mesotrione Lumax 3.95L 2.5 qt metolachlor atrazine mesotrione

25 Evaluated Plots and Conducted a Field Day

26 Effect of Dual II Mag on crop growth [X rate = 1.6 lb ai or 1.67 pt] Days (half life) PSU demo 2012

27 Effect of Atrazine 4L on crop growth [X rate = 1.5 lb ai or 3 pt] Days (half life) PSU demo 2012

28 Effect of herbicides on diakon or forage crop growth Days (half life) PSU demo 2012

29 Common corn and soybean herbicides, estimated half lives, cash crop restrictions and their potential to injure fall cover crops. Herbicide Active ingredient Normal Rate/acre Half life (days) 1 Cash crop restrictions 2,4 D 4S 2,4 D 1 2 pt 7 Plant anything 30 days after application OK to plant All grasses Fall cover crops Concern for Wait 30 days before planting sensitive broadleaves Other Amine formulations more water soluble and can leach into seed zone Atrazine 4L atrazine 1 2 qt 60 Can plant corn, sorghum, and soybean the following year (some products allow others) Sorghum species Cereals, ryegrass, legumes, and mustards More persistent in high ph soils (> 7). Rates < 1 lb/acre can allow more flexibility Callisto (includes Lumax, Lexar, Halex GT) mesotrione 3 6 fl. oz to 18 months for legumes and vegetables All grasses Small seeded legumes, mustards Sequential applications (PRE fb POST) increase the potential for injury Dual II Mag 7.62E/Cinch metolachlor 1.67 pt Labeled for use on many crops Almost anything Annual ryegrass or other small seeded grasses Higher rates and later applications more of a potential problem Impact 2.8SC topromesone 0.75 fl. oz 14 Alfalfa, canola, soybean and sunflower have a 9 mo. restriction Wheat, barley, oats, and rye are allowed after 3 mo. Ryegrass should also be OK Although many broadleaves are restricted, Impact does not have much soil activity We have not seen this herbicide carryover in PA. crops/fact sheets/herbicide persistence

30 Planning Ahead know your herbicide residual Check a current University Agronomy Guide recrop tables Check label for use restrictions recrop tables For species not listed, use related species (e.g. other small seeded legumes or grasses) Replicated small plot research has not been very successful difficult to draw recommendations and lots of work Demonstration trials using reduced rates and half life comparison: Very useful for demonstrating medium to longer residual herbicide activity on sensitive crops and herbicides with little soil activity (e.g. atrazine and topromezone)

31 Thank you Any QUESTIONS?