Weed Management in Direct Seeded Rice - By Anjali Patel mam (IGKV Raipur, C.G)

Weed Management in Direct Seeded Rice - By Anjali Patel mam (IGKV Raipur, C.G)

1. WEED MANAGEMENT IN DIRECT SEEDED RICE ( Oryza sativa L.) PRESENTED BY: ANJALI PATEL PhD scholar

2. Direct seeded rice Direct-seeding of rice refers to the process of establishing the crop from seeds sown in the field rather than by transplanting seedlings from the nursery. ( Farooq et al. 2011) principal methods of establishing the DSR dry seeding (sowing dry seeds into dry soil) wet seeding (sowing pre - germinated seeds on wet puddle soils) water seeding (seeds sown into standing water)

3. Ramzan (2003) reported yield reduction up to transplanted- 48% direct seeded flooded- 53% Direct seeded aerobic rice- 74% Aerobic rice is subjected to much higher weed pressure with a broader weed spectrum than flood- irrigated rice. ( Balasubramanian and Hill 2002) The critical period of weed competition Direct seeded rice 15-45 DAS Transplanted rice 35-45 DAS The greatest loss caused by the weeds, resulted from their competition with crop for growth factors, viz. nutrients, soil moisture, light, space, etc. ( Walia 2006)

4. Major weed species in direct-seeded rice Scientific Name Common Name Family Grasses Echinochloa colona Wild rice Poaceae Echinochloa crusgalli Barnyard grass Poaceae Eleusine indica Goosegrass Poaceae Leptochloa chinensis Sprangletop Poaceae Digitaria sanguinalis Large crab grass Poaceae Brachiaria ramosa Signal grass Poaceae Cynodon dactylon Bermuda grass Poaceae Dactylotenium aegyptium Crow foot grass Poaceae Broad-leaf weeds Alternanthera sessilis Khaki weed Amarathaceae Ammania baccifera Redstem Lythraceae Caesulia axillaris Pink node flower Asteraceae Celosia argentia Quail grass Amarathance Cleome viscosa Cleome Capparaceae Commelina benghalensis Wandering jaw Commelinaceae Commelina communis Dayflower Commelinaceae Cyanotis axillaris Creeping cradle Commelinaceae Digera arvensis Digera kondra Amarathaceae Sedges Fimbristylis miliacea Globefingerush Cyperaceae Cyperus difformis Small flower umbrella sedge Cyperaceae C. iria Flat sedge Cyperaceae C. rotundus Purple nut sedge Cyperaceae

5. Weed shift in DSR In India continuous use of grass killers such as butachlor in rice has resulted in a shift of weed flora to sedges as C. iria , Scripus spp., and Fimbristylis spp. (AICRP WC- 2002-03). Mortimer and Johnson 2008 during the study at Pantnagar confirmed that changing from transplanting to direct-seeding caused marked changes in the weed flora in the rice-wheat system. With direct-seeding of rice there was a rapid increase in annual grasses , Echinocloa colona , E.crus-galli , Leptochloa chinensis : perennial sedge Cyperus rotundus and certain broad-leaf weeds such as Caesulia axillaris .

6. Weed management approaches Preventive approaches To limit weeds introduction and their spread- Use of physical and genetically pure seeds Field bunds should be cleaned Structure used for irrigation and farming tools should be free from weed contamination.

7. Cultural approaches Stale bed technique and tillage Singh et al. 2009 reported 53% lower density in Dry- DSR after a stale seed bed than without this practice. Stale seedbed combined with herbicide ( paraquat ) and zero-till results in better weed control because of low seed dormancy of weeds and their inability to emerge from a depth >1 cm ( Chauhan and Johnson 2010) . mainly control Cyperus rotundus , Leptochloa chinensis , Eclipta prostrata , Digitaria ciliaris , and red rice etc.

8. Cont… Cont… Cultivar competitive to weed A cultivar which is more efficient in using the resources can be helpful for suppressing weeds (Swanton and Weise, 1991) Initial canopy cover, early maturing crop, rice hybrids have smothering effect on weed. ( Mahajan et al., 2011) Competitive rice cultivar effectively supp- ressed the infestation of Echinochloa spp. and helped reduce herbicide dependency. (Gibson et al. 2001)

9. Cont… Irrigation management Good water management together with chemical weed control offers an unusual opportunity for conserving moisture and lowering the cost of rice production. ( Rao et al. 2007) Fertilizer management Fertilization affects weed growth in rice fields. Manipulation of crop fertilization is a promising approach to reduce weed infestation and may contribute to long-term weed management. ( Blackshaw et al. 2004)

10. Cont… Seeding rate Higher seeding rates would be beneficial if no weed control is planned or if only partial weed control is expected. (Singh et al., 2016) Under conditions of aerobic soil, the growth of weeds was suppressed effectively by 300 seeds/m2 in direct seeded rice system. (Anwar et al., 2011) Crop rotation Rotating crops having dissimilar life cycles or cultural conditions (so as to break the cycles of the weeds) is among the, most effective of all weed control methods. (Singh et al., 2016) Planting mungbean in dry season in Northern India also reduced weed growth and weeding time and increased herbicide performance. ( Mahajan et al., 2012)

11. Cont… Residue management and co-culture Crop residue present on soil surface not only improves soil and moisture conservation but can also influence weed seedling emergence and weed growth. (Singh et al. 2016) Sesbania coculture reduced broad-leaf and grass weed density by 76-83% and 20-33%, respectively, and total weed biomass by 37-80% compared with sole rice crop. (Singh and Singh 2007)

12. Cont… Intercropping Resource availability is important for weed existence, intercropping offers an exceptional chance for managing weeds by better resource use. (Buhler, 2002) In direct seeding of rice for controlling the weeds, intercropping by sesbania used for 30-35 days was noticed efficient. (Singh et al., 2007b) Mulching In rice field where mulch was used, the population of grassy weed plants was less in complete crop growth cycle. (Singh et al., 2007)

13. Manual and mechanical control Harrowing has been found effective in direct seeded rice, especially when the crop plants are larger than weeds to escape damage. (Rasmussen and Accard 1995)

14. B iological control Biocontrol Agents used for controlling weeds in Direct seeded rice system Biocontrol Agent Targeted Weed Reference Curvularia tuberculate Cyperus difformis , Cyperus iria , Fimbristylis miliacea Luna et al. (2002a,b) Curvularia oryzae Cyperus difformis , Fimbristylis miliacea Luna et al. (2002a,b) Fusarium pallidoroseum , Myrothecium advena Eichhornia crassipes Praveena and Naseema (2003) Cochliobolus lunatus Echinochloa crus‐galli Chin (2001)

15. Cont… Allelopathic approaches Rice allelopathy can stifle both dicot and monocot weed. ( Olefsdotter et al., 2001) extracted from six- leaved seeding of rice restrict the growth of lettuce and Heteranthera limosa .

16. Chemical control Butachlor , benthiocarb or pendimethalin @ 1-1.5 ai.kg/ha as pre emergence. Oxadizon @0.5-0.75 kg/ha as pre emergence or early post emergence it control grasses, sedges and broad leaved ones. Pretilachlor @ 0.4-0.5 kg/ha or 0.75 kg/ha as pre-emergence at 3-5 DAS. pyrazosulfuron -ethyl @ 0.015-0.020 kg/ha pre –emergence at 1-3 DAS or as early post emergence at 10-15 DAS. Bensulfuron - methyl ( londax ) @ 50-60g/ ha at 20 DAS. Cyhalofop -butyl @ 0.19-0.28 kg/ha as post-emergence right of 1-2 leaf stage of rice untill 60 DAS for grass weed control. 2,4 D @ 0.75-1 kg/ha as post- emergence at 30-35 DAS to control broad- leaved weeds and sedges. Bentazon @ 1-2 kg/ha as post-emergence . Metsulfuron -methyl @ 4-8 kg/ha as post-emergence at 30-35 DAS control broad leaved weed. Almix ( Metsulfuron -methyl(10%)+ chlorimuron -ethyl (10%)+ 0.2% surfactant) @ 4g/ha at 3-5 DAS as pre-emergence or at 20 DAS as post –emergence.

17. List of herbicide used in direct seeded rice Herbicide Trade name Dose /ha application Ethoxy sulfuron ethyl Sun star gold 18g/ha POE Bispyribac sodium Nominee 25g /ha POE Butachlor Mechete 1-1.5 kg/ha PRE Oxadiargyl Top star 200-300g/ha PRE Halosulfuron methyl Halt/ Orcus 4-8 g/ha POE Pyrazosulfuron ethyl Accord 0.015-0.020 kg/ha POE Acetochlor Acetore 0.75-1 kg/ha PRE Pretilachlor Rifit 0.4-0.5 kg/ha PRE oxadiazon Ronstar 0.5-0.75 kg/ha Both chlorimuron – ethyl+ metsulfuron methyl Almix 4 g/ha POE

18. Researcher year place Findings Hussain et al. 2008 Rice Research Institute Kala Shah Kaku , Lahore To manage the weeds in direct seeded rice, four weedicides ( SunStar Gold 60 WG, Nominee100 SC, Stallion 13.75 WG and SunStar 15 WG) were tested and compared their efficacy with handweeding . Among the weedicides Nominee 100 SC ( bispyribac sodium) and Sunstar Gold 60 WG ( Ethoxy sulfuron ) proved as the best weedicides with 90.5 and 87.19% weed control respectively. The paddy yield in both the weedicide treatments was also comparatively higher than other weedicides . Khaliq et al. 2012 Faisalabad Bispyribac sodium, ethoxysulfuron ethyl and penoxuslam were used as early post emergence (15 days after sowing; DAS) at label dose of 30, 30 and 15 g a.i . ha-1, respectively. A weedy check and manual weeding (15 and 25 DAS) were maintained for comparison. Bispyribac sodium suppressed both weed density (75%) and dry weight (80%) over control that was highest among all herbicides. Post emergence application of bispyribac sodium appeared to be viable strategy for weed control in direct seeded rice with higher economic returns.

19. Researcher year place Findings Moorthy and Manna, Pellerin and Webster 1993 2004 Application of different pre-emergence herbicides including thiobencarb , pendimethalin , butachlor , oxadiazon and nitrofen has been found to control weed satisfactorily in direct seeded rice. Mann et al., Singh et al., Mahajan et al. 2007 2008 2009 Among the post emergence herbicides, ethoxysulfuron , cyhalofop -butyl, pretilachlor , chlorimuron , metsulfuron , bispyribac sodium and penoxsulam effectively controlled weeds in direct seeded rice Bhurer et al. 2013 Bara, Nepal A field experiment was conducted to evaluate effectiveness of different weed management practices; weedy, weed free and other five practices with pre and post-emergence herbicides; Pendimethalin , Pyrazosulfuron , Penoxsulam , Bispyribac , Azimsulfuran , 2,4-D, plus one to two hand weeding on the performance of DDSR. Among the weed control practices, application of pendimethalin (1 kg.a.i /ha.) followed by 2,4-D 1 kg a.i ./ha at 25 and hand weeding 45 DAS was found the best for obtaining higher yield and weed control efficiency in DDSR.

20. Effect of treatments on dry matter of weeds, WCE, grain yield and weed index in DSR field (pooled data of three seasons) Treatment Dose (g/ha) weed dry weight at 60 DAS (g/m2 ) WCE (%) Grain yield (t/ha) Weed index B:C ratio Carfentrazone -ethyl 20 22.93 (4 .84) 9 0.6 3.68 9.5 2.36 Carfentrazone -ethyl 25 27.48 (5 .29) 8 8.8 3.32 18.5 2.14 2,4-D Na salt 800 8 .08 (2 .93) 9 6.7 3.65 10.3 2.36 Weed-free 11.13 (3 .41) 9 5.4 4.07 - 2.32 Un weeded 245.3 (15.68) - 1.14 72.0 0.84 LSD (P=0.05) 1.18 0.03 Figures in parentheses are transformed values; Source:- Raj et al., 2013 ( Rice Research Station, Moncompu , Alappuzha , Kerala)

21. Integrated weed management None of the control measures in single can provide acceptable levels of weed control. Integration of higher seed rate and springapplied fertilizer in conjunction with limited herbicide use managed weeds efficiently and maintained high yields. ( Blackshaw et al. 2005) Adoption of IWM approach for sustainable rice production has been advocated by many researchers. ( Azmi and Baki 2002, Sunil et al. 2010, Jayadeva et al. 2011).

22. Conclusion DSR with suitable conservation practices has potential to produce slightly lower or comparable yields as that of TPR and appears to be a viable alternative to overcome the problem of labour and water shortage. Weeds, however, are the major constraints to direct-seeded rice production. To achieve effective, long term and sustainable weed control in direct-seeded system, there is a need to integrate different weed management strategies, such as the use of a stale seeded practice, the rotation of different direct-seeded systems, the use of crop residue as mulches, the use of weed competitive cultivars with high yield potential, appropriate flooding depth and duration, appropriate agronomic practices (row spacing, seeding rates and manual or mechanical weeding), and appropriate herbicide mixtures, timing, and rotation.