Importance of weed management and types of weeds.pptx

Importance of weed management and types of weeds

1. Importance of weed management and types of weed Presented by..... Paritosh Murmu , Scientist

2. What is weed???? A weed is a plant growing where it is not wanted Weed is an unwanted plant A plant growing with desired plant A plant with negative value There are over 30,000 species of weeds around the world of which 18,000 cause serious losses to crops.

3. Demerits of weed Yield loss : Yield loss due to weed is more than 33%, disease-26%, insect pest -20% and others-21% ii. Disease and pest incidence : Weed act as alternate host to pest and diseases in off season, which infect crop latter stage and damage crop. Crop Pest Alternate host Rice Stem borer Echinochloa sp Arhar Gram caterpillar Datura , Amaranthus Tomato Wilt Amaranthus

4. iii. Poor quality of produce : Contamination of foodgrains with weed seeds of Datura , Argemoe , Brassica etc. is harmfull to human health. Weed seeds present in the produce cause odd odours to flour Crops Weeds Sugarcane Aeginitia , Striga Tea Aeginitia Off flavour of milk Wild onion Sheep wool quality Cocklebur iv. Human Health problem : Health problem Weed Hay fever and Asthma Pollen of Ambrosia, Franseria Dermatitis(skin allergy ) Parthenium , Ambrosia Itching and inflamation Utrica sp African sleeping sickness Brush weed Malaria, Encephalities and Filaria Pistia , Salvinia

5. v. Animal Health problem : Problems related with Animal Weed Hypersensitivy to light Lantana camera Diarrhoea and blood strain in milk Rhododendron Anti blood coagulant Mellilotus alba vi. Water Contamination : Unfit for drinking Menace to fishing Upon decomposition emits offensive odour and pollute atmosphere

6. Merit of weeds Source of resistance to disease and pest.. Wheat (Cold tolerant) Triticum dicoccum Aegilops squarosa (Grass) Potato S.Stenotomum S.Sparsipillum (Weed)

7. ii. Fodder value : As green grass, hay, silage iii. Green Manure iv. Medicinal value Weed Medicinal value Leucas aspera Snake bite Calotropis procera Gastric trouble Phyllanthus niruri Jaundice Striga orobanchoids Diabetes v. Other benefits : Weed Products Andropogon Aromatic Oil Cyperus rotundus Agarbaties Imperata cylindrica , Typha Thatching roofs Cynodon ( Durba ), Dicanthium Protecting bunds

8. Types of weeds Weeds can be classified in different ways, the important clasification that helps in selecting weed control methods are based on cotyledon number, morphological and other characters. Classification based on ... Morphological character : Grasses : All grassy plant belongs to graminae family, narrow leaf, upright leaf eg . Durba grass b) Broad leave : All dicotyledonous plant, broad leaf eg . Bethua , c) Sedge : Weeds belongs to cyperaceae , triangular stem. Eg . mutha

9. ii. Based on duration :: Annual weed : Weeds grow and mature within one year or one season eg . Bathua b) Biennial weed : Weeds live for two seasons with a duration upto two years eg . Dauus carota , alternanthera echinata c) Perennial weed : Weeds live for more than two years eg . Durba , mutha grass iii. Based on number of cotyledons : Monocot : All grasses having narrow leaf eg . Durb grass Dicot : Broad leaf horizontal leaf eg . Bathua

10. iv) Based on habitat : Terrestrial : weeds growing in land eg . Bathua , mutha , durba grass b) Aquatic : Weeds growing in water body eg . Pistia , salvinia , hydrilla c) Amphibious : Weeds growing both in land and water Alternanthera philoxiroids v) Based on dependent on other host : Total parasite : Totally depend on host plant for food materials eg . Cuscuta , Orobanche b) Semi parasite : Partially depend on host plant for food materials eg . Striga , loranthus c) Independent weed : Do not depend on host plant for food materila eg . Durba grass, mutha grass

11. vi) Based on growing season : Kharif weed : weeds growing only in kharif season eg . Mutha ( cyperus iria ) b) Rabi weed : weeds growing in rabi season eg . Bathua , phalaris minor c) Summer weed : weeds growing in summer season eg . Argemone maxicana , solanum nigram vii) Based on soil reaction : Weeds growing in acid soil eg . Rumex , pteridium b) Weeds growing in saline soil eg . Salsola , suaeda c) Weeds growing in alkaline soil eg . Agropyron , sporobolus

12. Weed management There are four methods of weed management eg . Cultural, physical( mechenical ), biological and chemical method. Every methods has its advantages and disadvantages. No single method is successful in all conditions. So combination of different methods leads to effective and economic weed control. Cultural method : Practices like proper tillage, planting, fertiliser application, irrigation, selection of variety, time of sowing, cropping system etc. Reduce weed growth . Fiel Preparation : Deep ploughing in summer season which cause scroching of rhizomes and tubers of weed.. ii ) Cropping system : The possibilities of a certain weed species occuring is greater if the same crop is grown year after year. Mutha grass can be controlled by including lowland rice

13. iii) Selection of varieties : Varieties with rapid growth, profuge foliage reduces weed growth eg . Maize, sunflower, sorghum while potato, sugarcane, cotton permits weed growth due to initial slow rate of growth. iv) Planting density : Closer planting reduces weed growth while distant planting encourage weed growth v) Fertiliser application : Crop like rice, maize, sorghum grow at a faster rate when nitrogen is applied and cover the soil earlier. Weeds like mutha , durba do not respond to nitrogen and they are suppressed by fast growing crops. vi ) Irrigation : Method of irrigation controls the weed growth. Weed infestation increases in order of flood>sprinkler>drip methods .

14. B) Physical Methods : Physical force either manual, animal or mechanical power is used to pull out or kill weeds. Hand weeding : Pulling out weeds by hand or uprooting weeds by using small hand tools. ii) Hand hoeing : Entire surface soil is dug to a sallow depth with the help of hand hoes iii) Digging : Digging up to a deeper layers to remove underground storage organs. Ve rry usefull for perennial weed by pick axes or crow bars. iv. Mowing : Mowing is the cutting of weeds to the ground level. It is usually practiced in lawns, gardens wherein the grass is cut to a uniform height to improve the aesthetic value. The common tools used are sickle, scythe and lawn mower.

15. Dredging and chaining : Used for aquatic weeds where weeds are removed along with their roots and rhizomes with the help of heavy chain is pulled over the water bodies. vi) Burning and flaming : It is the cheapest method of eliminating mature unwanted vegetation from uncropped areas . vii) Mulching viii) Intercultivation : Most effective in line sowing crops.

16. Biological weed control It is the utilisation of living organisms ( bioaagent ) like insect, pathogen and competitive plants to limit weed infestation. Objective is not to eradicate but reduction and regulation of weed population below the level of economic injury. Important criteria of bioagent : Host sepeific ii. Fast damaging ability iii. Adaptibility to new environment iv. Efficient reproduction v. Freedom from natural enemies

17. Some examples of biological weed control : Lantana camera controlled by beetles Octotoma scabripennis and Uroplata giraldi Alternanthera phyloxiroid contolled by Agasicles hygrophyla Weed control by insects Weed control by Fungi Water hyacinth controlled by Rhizoctonia blight Opuntia controlled by mite ( Tetranichus sp) Water hyacinth controlled by snail (Marisa sp) Water hyacinth controlled by fish (common carp, chinese carp) Water hyacinth controlled by mammals (sea-cow) Weeds in maize crop can be controlled by growing cowpea in between maize rows.

18. Chemical Weed Control Chemicals that are used to kill plants or weeds called herbicide. Their use has been increasing rapidly since 1944 when 2,4-D was first used as herbicide. Classification of herbicides : Based on molecular composition Organic herbicides : Herbicides contain carbon in their molecule ex. Diesel oil, xylene type aromatic oil ii. Inorganic herbicides : Herbicide do not contain carbon atom in their molecules. Ex. Arsenic acid, sulfuric acid, cupper sulphate

19. Based on selectivity Selective herbicide : Kills only targeted plants or weeds while crops are not affected. Ex. Simazine , atrazine , 2,4-D, butachlor , alachlor , pendamethalin Non selective herbicide : Kill all vegetation that come in contact with it. Ex. Paraquat , Diaquat , Gluphosate Though selectivity depends on dosage, when atrazine applied at 1kg ai /ha kills weeds without harming sorghum. If applied 10 kg ai /ha becomes non selective. Based on translocation : Systemic herbicides : Move within the plant and kills the plant Ex. Atrazine , simazine , propanil , 2,4-D, Contact herbicides : Kills the plant when come in contact with plants. Ex. Diquat , paraquat .

20. Herbicide Formulation Herbicides in natural state may be solid, liquid, volatile, non volatile, soluble or non soluble. Herbicides in natural state are difficult to apply. So, herbicides are formulated as soluble powder (SP), Wettable powder (WP), or in emulsifiable form etc. To make them biologically effective adjuvents are added to increase surface retention, for easy application, long storage.. Soluble powder (SP) : Easily soluble in water ex. 2,4-D (sodium salt), dalapon , endothal Soluble concentrate (SC): This are soluble liquid ex. 2,4-D amine, diquat , paraquat . Wettable powder (WP) : These are of low solubility in water, so require continuous agitation to prevent their settling. Atrazine 80%,diuron 80%, isoproturon 70%. 4. Liquid suspension (LS) : These are not soluble in water, so it is solubilised in organic solvets . Ex. Cyprazine , nitralin

21. 5. Emulsifiable concentrate (EC) : Active ingradient is dissolved in solvents and an emulsifire is added to it for uniform distribution of chemical in water, no stirring is necessary. Ex. 2,4-D ester, nitrofen , diallet .. 6. Granules : Small pelllets or granules are made with inert clays. The toxic solution is sprayed on these granules. The granules are then packed for subsequent use. Ex. Granules of butachlor , 2,4-DEE. Mode of action of herbicide The most important physiological processes of plants like photosynthesis, respiration, biosynthesis of protein, fat, vitamin and cell divission , germination are hampared .

22. Inhibition of photosynthesis : Herbicides of group triazine , ureas , carbomate 2. Inhibition of respiration : Herbicides of group dinitroanilines inhibit respiration process of plant and kill it. 3 . Inhibition of protein synthesis : Herbicides of group amide stop protein synthesis and kill the plants. 4. Inhibition of fat synthesis : Herbicides of group thiocarbamate inhibit the fat synthesis and kill the plants. 5. Inhibit the vitamin synthesis : Dalapon stops vitamin synthesis. 6. Inhibition of cell division : Herbicides of group carbamate and dinitroaniline inhibit cell division and kill the plant. 7. Inhibition of germination : Amide group of herbicide inhibit seed germination.

23. Time of herbicide application Fallow application : More than 10 days before sowing of crops. Pre-plant application : 2-10 days before sowing of crops. Normally volatile herbicides like Fluchloralin , Trifluralin are incorporated into the soil to avoid volatilization loss. Pre-emergence application : 1-4 days after sowing but before emergence of crop and weeds. Post- emergence application : Application of herbicide after emergence of crops. It is normally done 30-40 days after sowing.

24. Methods of application Soil application : Soil surface application : Herbicide is sprayed on the soil surface, penetrate few centimeter into the soil and kill the germinating weed. EX. Triazines , amide and ureas group of herbicides. Soil incorporation : Volatile herbicides are incorporated into the soil to prevent the volatile loss. Ex. Dinitroaniline group of herbicides. Band application : Hebicides like atrazine are applied in between the crop rows at the time of sowing. Foliar application : Blanket application : Herbicide application over the entire crop area. Herbicide should be Highly selective . Directed application : Apply in between the crop rows . Spot application : Heavy dose of herbicide poured only in weedy areas. Basal bark application : For tree weeds the basal bark is removed and drenching of that area with herbicide solution. Cut surface application

25. Thank You For Your Kind Attention