Weed Dynamics and Management in Conservation Agriculture Chhokar R.S.1*, Das T.K.2, Choudhary V.K.3, Ankur Chaudhary4, Rishi Raj2, Vishwakarma A.K.5, Biswas A.K.5, Singh G.P.1, Chaudhari S.K.6 1ICAR-Indian Institute of Wheat and Barley Research, Karnal, Haryana 2ICAR-Indian Agricultural Research Institute, New Delhi 3ICAR-Directorate of Weed Research, Jabalpur, Madhya Pradesh 4CCS Haryana Agricultural University, Hisar, Haryana 5ICAR-Indian Institute of Soil Science, Bhopal, Madhya Pradesh 6Krishi Anusandhan Bhawan II, Indian Council of Agricultural Research (ICAR), New Delhi *Corresponding author, Email: rs_chhokar@yahoo.co.in
Online published on 22 March, 2022. Abstract The large-scale benefits of conservation agriculture (CA) have resulted in shift from conventional tillage to conservation tillage. This shift in tillage practice has also resulted in the shift in weed flora as well as weed management strategies for sustainable crop production. The weed shift in CA is being realized mainly due to adoption of no tillage, crop residue retention and crop rotation. Adoption of notillage practices increases the infestation of small seeded and perennial weeds and concentrates weed seeds in upper soil layers. The adoption of no-till wheat under rice-wheat system increases the infestation of broad-leaved weeds (Rumex dentatus, Medicago denticulata, Sonchus oleraceous) but decreases the infestation of Phalaris minor. Similarly, the adoption of no-till direct seeded or transplanted rice has shown abundance of water logging sensitive weeds such as Trianthemaportul acastrum, Dactyloctenium aegyptium, Digitaria sanguinalis, Cyperus rotundus and Digera arvensis and, which are virtually not observed in transplanted puddled rice. Weed management is really a challenge during the transition phase of CA in crops having restricted post-emergence herbicide options. The success of CA system depends on the efficient weed management with usage of herbicides as pre-planting (non-selective) and post-emergence (selective) options. The pre-plant non-selective herbicides such as glyphosate, glufosinate and paraquat will remain the key weed control tool in CA. The efficacy of pre-emergence herbicides in CA can be reduced due to their interception with crop residue mulch. Proper selection of herbicide, time and method of application as well as spray volume can improve the efficacy of pre-emergence herbicide in CA. However, the over reliance on herbicides alone is not desirable and will lead to shift in weed flora towards the tolerant and resistant ones, hence removal of escaped weeds has been advocated to avoid such situations. In CA system, the absence of tillage, which is otherwise utilized for weed control, presents challenges of designing suitable alternative weed management strategies involving crop plants competitiveness against weeds. Several cultural practices which can be useful are adjustment in crop row spacing, orientation, seeding density and sowing time, and use of competitive crop cultivars, residue mulching, diversified crop rotation, weed seed harvest, allelopathy and cover cropping. The integration of non-chemical and chemical weed management tools has to be utilized as the potential strategy for sustainable weed management in CA. Top Keywords Conservation agriculture, herbicide, mulching, tillage, weed shift. Top |