Title of Course Organic Farming Class B. Sc. Ag , Third Year Topic Weed Management in Organic Farming College College of Agriculture , Jabalpur By Dr Amit Kumar Jha INTRODUCTION rice (Oryza sativa), Chulai(Amaranthus spp), Gullidanda (Phalaris minor), Bhang Weeds have been the problem since (Cannabis sativa), mexican poppy the agriculture came into existence as these (Argemone mexicana), Hiran Khuri compete with the crop of interest for various (Convolvulus arvensis) etc. Some of them resources and also act as hosts for different are allergic and noxious such as P diseases and insects. Losses in Indian hysterophorus (congress/carrot grass), agriculture due to weeds account for 33 per Cirsium arvense (Canada thistle), cent. Among the different weeds some of the Stinking nettle (Bichhu Buti) etc. The important ones are: congress grass ubiquitous presence of such plants is (Parthenium hysterophorus), wild oat responsible for health problems from skin (Avena fatua), Dudhi (Euphorbia spp), Bathu allergies to breathing trouble and sinusitis (Chenopodium album), Phoolakri (Lantana injurious to livingorganisms (Jose and Saini camara), Doob (Cynodon dactylon), 2015). For the weed management motha (Cyprus rotundus),wild conventionally chemical herbicides are being used. The herbicides are very Cultural practices effective for weed control but they prove to be detrimental in various ways for Crop rotation: The weeds such as P example some of them have residual minor, A fatua etc which are associated effects, some make the soil sick, some with the specific crops can be controlled by cause air pollution thereby respiratory or means of crop rotation. These weeds can skin problems, some cause water be managed in wheat field by growing pea, pollution and some of them are harmful to gramorpotato in rotation. the organisms which are boon to agriculture.Theherbicideconsumptionin India Cover cropping: The vacant inter-row which was negligible till 1970s now has spaces in the fields provide space for weed increased up to 20000 MT (Anon 2015). growth and development. This space can be On the other hand traditional or organic utilized for extra income by the farmers. The weed management practices which leguminous crops such as pea, Urd, cow exclude the use of inorganic products in pea etc are preferred for this purpose. Thisnot any way do not have such problems and only preventsweedgrowthbutalso replenishes also prove to be equally effective for weed soilnutrientsandpreventssoil erosion. management. Hoeing and hand pulling: Hoeing and Following non-chemical methods hand weeding are the most commonly used may be applied in agriculture for effective practices. These practices completely weedcontrol: destruct the shallow rooted weeds. These also help in aeration of soil and breaking of Preventive measures capillaries by hoeing thus preventing Once the weeds appear in the field evaporationofsoilwater. they cause great trouble in various ways. Different preventive measures for weed Water management control are: use of seeds from the reliable sourcesortousecertifiedseeds,preventing the Flooding: This method is very helpful in entry of livestock into the crop land, cleaning some crops such as paddy. Paddy plants theequipmentssuchasharvesters, cultivators, can grow well in the submerged conditions but seed cleaners etc before and after field weeds can not do so. Water is kept operations, keeping the irrigation channels standinginthefieldfor6-8weeks. weed free, using only well rotten manures in which weed seeds have been decomposed Drip irrigation: In some cases flooding by microorganisms and applyingthefertilizers helps in proliferation of weeds especially the near the rowsor plants and avoiding summer and winterseason weeds. broadcasting. Organic weed management Therefore irrigation should be done as per the Use of primed seeds requirement of plants. For this purpose drip Seed priming in an osmotic solution irrigation is very successful alternative (PEG 6000,mannitol,cocopeat, vermiculite, KCl, especiallyforhorticulturalcrops.I KNO3 etc) before sowing that enhances germination and increases seedling Mulching emergence uniformly under adverse Mulches not only contribute for environmental conditions. The desirable weed management but also conserve soil crop will emerge faster than weeds and moisture and maintain the soil temperature therefore prevent the growth of weeds by necessary for growth and development of the cuttingoffthesupplyoflightandnutrients. plants.Differentmulcheswhichcanbe used for weedmanagementareexplained hereunder: Soil solarisation Soil solarisation controls soil borne Organic mulching: The crop residues, pine pests usingradiant energyfrom the sun. This is needles, paddy straw etc can be utilized to very effective method to kill the weeds check the weed growth which act as especially in summers or before onset of organic mulches. Organic mulches also winters.Thesoilisirrigatedfirsttopromote weed prove to be an excellent mean for soil emergence and then covered with clear moisture conservation especiallyin winters and plastic film after tillage. The heat trapped summers. insidekillstheweedsandalsokills the embryos insidethedormantseeds. Inorganic mulches: To check the weeds the mulchmustblocknearly allthelightthat reaches Plant geometry thesoilsothatweedswhichemerge underneath Different studieshave shown that the the mulch do not have enough light to closer planting of crops gives perfect survive. Sometimes the black polythene competition to weeds by reducing the mulch may be used for such purpose. amount of light and nutrients required for weeds. Living mulches: Living mulches are usually plant species which do not attain much height Mechanical control such as clover planted before or after a crop. Living mulches should be well Tillage/cultivation: Tillage between the managed to avoid competition with main rows or the cultivation of fallow land two- three crop. Inter-row spaces can be utilized for times causes significant reduction in weed living mulches. population. For this disc harrow, cultivator etcmaybeusedwithpowertiller or tractor. (Anon 2015) Fig 1. Crop yield losses caused by weeds and other pests in India (Anon 2015) Fig 2. Herbicide consumption trends in India Table 1. List of different organisms/plants helpful in weed management Common name Botanical name Bio-agents of weed of weed Insects Alligator weed Alternanthera Agasicles hygrophyla philoxeroides Congress grass Parthenium Zygogramma bicolorata hysterophorus Hyacinth Eichhornea Mite (Orthogalumna terebrantis), Neochetina bruchi, crassipes Neochetina eichorniae, Sameodesalliguttalis Motha or sedge Cyperus rotundus Bactra verutana grass Phoolakri or Lantana camara Crocidosema lantana, Teleonemia scrupulosa, Ophiomyia Panch Phooli lantanae, Octotoma scabripennis and Uroplata giraldi Prickly pear Opuntia dilleni Dactylopius opuntiae, Dactylopiustomentosus, weed Dactylopius indicus, mite (Tetranychus sp) Water fern Salvinia molesta Crytobagus singularis, Paulinia acuminate Fungi Amarbel or Cuscutta sp Colletotrichum sp dodder Hyacinth Eichhornea Rhizoctinia sp, Cercospora rodmanii crassipes Johnson grass Sorghum Biopolaris sorghicola halepense Multiple weeds - Streptomyces hygroscopius Vetch Aeschynomene Colletotrichum sp virginica Competitive plants Congress grass Parthenium Cassia sericea hysterophorus General - Cow pea, berseem, lucerne, millets vegetation Allelopathic crops General - Sunflower, buckwheat, barley, rye, oats, sorghum, wheat, vegetation carrot, radish Herbivorous fishes Aquatic weeds - Chinese carp, white amur, silver carp, common carp Organic weed management Mechanical control reproductive phase thus preventing weeds’ seedproductionfornextgeneration. Tillage/cultivation: Tillage between the rows or the cultivation of fallow land two- three Summer ploughing: The advantage of times causes significant reduction in weed summer ploughing may be taken by population. For this disc harrow, cultivatoretc exposing the weed seeds to various maybeusedwithpowertiller or tractor. environmental stresses. Flame method: The weeds that emerge Biological control before the main crop can be managed by a It involves utilization of living hot flame passed quickly over them. The organisms/plants such as insects, fungi, weeds between the rows can be easily competitive crops, allelopathic crops and killed. This is particularly very useful in herbivorous fishes for the suppression/ crops which take longer time to emerge control of the weed population. Some of the such as carrot. An advantage of this important biocontolagents have been listedin method over the tillage or cultivation is that Table1. it does not disturb the soil and also does not promote the germination of the dormant CONCLUSION weeds. Weeds cause significant loss in Stale seedbed technique: Stale seedbeds agriculture by competing with main crop for are prepared 2-4 weeks prior to crop nutrients and other resources and also act as seeding in which weeds are allowed to alternate hosts for diseases or pests. The use emerge and killed while they are still small by ofchemical herbicides has many ill effects shallow cultivation. This can be repeated twice on environment and ecology. Therefore or thrice depending upon the availability various organic and ecofriendly practices of time. This technique significantly which are equally effective may be used reduces the weed population that emerges for the weed management. afterthe cropis planted. REFERENCES Mowing: Mowing can be done in the inter- row spaces. Regular mowing is needed to prevent Anonymous 2015. Vision 2050. Directorate of Weed theweed-cropcompetitionandalso to prevent Research (ICAR), Jabalpur, MP, India, 32p. the weeds to shift into Jose P and Saini SM 2015. Common weed giving you allergies. The Times of India, 2 July 2015. View publication stats.