parasitic weeds.pptx
- 1. BIOLOGY AND ECOLOGY OF PARASITIC WEEDS AND THIER MANAGEMENT AGR:503 PRINCIPLES AND PRACTICES OF WEED MANAGEMENT COURSE TEACHERS Dr. P. Murali Arthanari Dr. G. Senthil kumar PRESENTED BY K. Aravind 2021502021
- 2. INTRODUCTION ◦ About 4,000 flowering plant species have adapted to parasitize other plants. Unfortunately for farmers, a small number of these species have become weeds, posing severe constraints to major crops including grain and forage legumes ◦ Parasitic weeds are the plants which attack other plants bymaking connections and deriving part or all of their food from the host.
- 3. ◦ They attach themselves either to the roots or the shoots of the host plants and survive on food material available in them. ◦ Due these parasites include some of the world’s most devastating agricultural pests and are influential, fascinating components of natural communities ◦ Among the major pests of agricultural crops, weeds alone caused severe yield losses ranging from as low as 10% to as high as 98% of total crop failure in the dry land regions.
- 4. PARASITIC WEED ◦ The parasite weeds are either total or partial which means, the weeds that depend completely on the host plant are termed as total parasites while the weeds that partially depend on host plant for minerals and capable of preparing its food from the green leaves are called as partial parasites. Those parasites which attack roots are termed as root parasites and those which attack shoot of other plants are called as stem parasites
- 5. ◦ The most economically important parasitic weeds are the broomrapes (Orobanche), Striga and dodders (Cuscuta spp.) damaging different crops ◦ Parasitic weeds can be difficult to eradicate because they often produce large numbers of long-lived seeds ◦ In addition, parasitic plants that attack host roots can inflict serious damage to crop plants before the latter emerge from the soil, making it difficult to diagnose infestations before economic losses occur
- 6. Crop bound weeds or parasitic weeds ◦ Parasitic weeds which are also referred to as Crop-bound, do not produce their own food by themselves and, therefore, necessarily parasitize partially or wholly a crop for their food and survival, e.g. Cuscuta sp, Orobanche sp, Striga sp, Loranthus longiflorus, Cassytha filiformis. ◦ They remain dependent upon crops and other wild hosts for food. Crop rotation can be of immense use against them, but longer viability in many parasitic weed seeds defies short-term crop rotation measure.
- 7. ◦ Crop-bound weeds because of their large/huge species diversity also infest a large number of crops of economic importance. ◦ Unlike autotroph weeds, which affect the crops indirectly by removing nutrients, water from soil or competing with crop plants for space and light, the parasitic weeds affect crop growth directly by sharing/taking away food from the crops
- 8. Accordingly weeds are classified as Total parasitic weeds: These weeds are totally dependent on host plants as they take moisture, nutrients and food from host plants e.g. Orabache sp. It is usually parasitized tobacco, tomato, carrot, sarson etc..
- 9. Semi parasitic weeds: Those weeds are partly dependent on host plant and partly on their own are called semiparasitic weeds e.g. Cascuta sp like Cuscuta reflexa and Cuscuta chinensis and Striga sp. These weeds after germination of host crop seeds germinate and their radicles attach to the roots of host crops. After their germination they produce and synthesize food materials, but they take water and nutrients from the host crops
- 10. Non parasite weeds: Those weeds which are not dependent on any other plants. These weeds germinate, take nutrients from soil and synthesis their food for themselves e.g. Cyperus rotundus, Echinochloa sp, Phalaris minor, Chenopodium album etc.
- 11. TYPES OF PARASITIC WEEDS Total root parasite – Orabanche cernua on Tobacco Partial root parasite - Striga lutea on sugarcane and sorghum Total stem parasite - Cuscuta chinensis on leucerne and onion Partial stem parasite - Loranthus longiflorus on mango and other trees
- 12. Total root/holo-root parasite: They take away food from the host-roots and do not have any other source of gathering food. Therefore, they are also called “obligate root-parasite.” For example, Orobanche sp (on tobacco, tomato, fababean, chickpea, mustard, etc).
- 13. ORABANCHE
- 14. INTRODUCTION ◦ It is a total root parasite. ◦ Serious phanerogamous parasite of tobacco. ◦ It also attacks other crops than tobacco. ◦ A single plant carries 10-100 flowers and hence, may produce 1,00,000 or more seeds. ◦ There are more than 150 species
- 15. BIOLOGY ◦ Broomrapes are dicotyledonous annual plants (10-60 cms tall, depending upon the species) and recognized by its yellow to straw coloured stems, bearing yellow, white,or blue, snap dragon like flowers. ◦ The leaves are merely triangular scales and both stem and leaves show absence of chlorophylls. Flowers appear in the axils of leaf and are white and tubular. ◦ The fruits are capsular and contain numerous tiny black seeds ◦ Each capsule contains 600-800 seeds and a single plant may produce more than one lakh seeds depending upon species
- 16. IMPORTANT SPECIES OF ORABANCHE ◦ Orabanche aegyptiaca (Egyptian broomrape) ◦ O. ramose (Branched broomrape) ◦ O. crenata (Bean broomrape) ◦ O. cernua (Nodding broomrape) ◦ O. minor (Common broomrape)
- 17. orabanche aegyptiaca orabanche ramosa orabanche crenata
- 19. Host plants Tobacco Tomato Potato Pepper Mustard Groundnut Cowpea Cauliflower Broad bean Sunhemp Sun flower Safflower Cabbage
- 20. Orobanche in sunflower Orobanche in tomato Orobanche in tobacco
- 21. SIGNIFCANCE ◦ Orabanche is popularly known as broomrape in English speaking countries ◦ It is flowering parasite on tobacco roots in all tobacco tracts in india. ◦ Its is a holoparasite and draws its nourishment from tobacco by means of haustoria attached to the roots of tobacco.
- 22. Global ◦ Mediterranean region ◦ Europe ◦ Africa ◦ Newzealand ◦ Australia ◦ America India o Haryana o Punjab o Madhya pradesh o Andhra Pradesh o Tamil nadu o Karnataka o Maharashtra
- 23. Management Preventive Methods Use healthy and certified planting materials of improved varieties free from weed seed contamination . Clean farm machinery and equipments to prevent the movement of infested soil to new areas. Practicise deep tillage during summer months . Collect the parasitic weeds prior to flowering and burn . Use well rotten decomposed green manure if needed.
- 24. Cultural methods ◦ Crop rotation with non host crops like wheat , barley, rice. Chickpea etc. ◦ Trap and catch crops found effective and may help to reduce seed bank of orabanche species ◦ Trap crops – pepper, sorghum, cowpea, sunhemp, mungbean , alfafga, soyabean, chickpea ◦ Delaying sowing dates – 2 weeks after the optimal rate of sowing ◦ Increased cropping density may reduce competition .
- 25. Physical method ◦ Hand pulling before flowering followed by burning ◦ Tillage – deep tillage during summer months ◦ Deep inversion ploughing and fire – placement of seeds at 20 cm depth cause little emergence of orabanche and the buried seeds could be brought up by subsequent tillage ◦ Soil solarisation – covering moist soil with white or black polythene sheet for a month can increase the soil temperature by almost 10℃ results in orabanche seeds .
- 26. Biological method ◦ Management of orabanche through biological perpetuation of a fly ,phytomyza orabanchia ◦ Inoculation of fungus fusarium oxysporum .f.sp.Orthoceras in the field ridges 90 %control
- 27. Chemical method ◦ pre emergence - sodium 2,4 – d ethyl sulphate ◦ Post emergence - ally alcohol ( 0.1 to 0.2 %) ◦ Directed post emergence DNDC (0.40 to 0.75) ◦ Soil fumigant like methyl sodium or dazomet is very effective . ◦ Seed treatment with imidazolinolines is found effective .
- 28. ◦ Partial root/hemi-root parasite: ◦ Initially they depend upon host-roots for their food and living (subterranean/ under-ground stage in case of Striga), but later after emergence from soil, they are green, chlorophylls and can produce their own food. For example, Striga hermonthica/asiatica (=lutea) on sorghum, maize and Striga gesneroides on cowpea
- 29. STRIGA
- 30. INTRODUCTION ◦ Striga has been given the common name of "witchweed" because it attaches itself to the roots of the host plant thus depriving it (the host) of water and nutrients. ◦ Striga spp. (witch weeds) belongs to the family Orobanchaceae ◦ Economically important Striga species are reported from more than 50 countries, especially from East and West Africa and Asia
- 31. HOST CROPS ◦ Sorghum (sorghum bicolor L., ◦ Maize (zea mays l.), ◦ Pearl millet (pennisetum glaucum l.), ◦ Sugarcane (saccharum officinarum l.) ◦ Rice (oriza sativa l.)
- 32. Striga in sorghum Striga in maize Striga in sugarcane
- 33. Different species of striga ◦ Striga hermonthica (purple witchweed or giant witchweed) ◦ Striga asiatica (Asiatic witchweed or the red witchweed) ◦ Striga densiflora (Denseflower Witchweed) ◦ Striga gesnerioides (Cowpea witchweed) ◦ Striga angustifolia
- 34. Striga hermonthica Striga asiatica Striga densiflora
- 35. Striga gesnerioides Striga angustifolia
- 36. Global ◦ Africa, ◦ Asia and ◦ Australia India o Gujarat o Karnataka o Mdha pradhesh o Maharashtra o Rajasthn o Tamilnadu o Uttar pradhesh
- 37. Biology ◦ Striga plants have green opposite leaves, bright irregular flowers with corolla tube slightly bent at the middle. ◦ The flowers are pink, red, white or yellow. ◦ There is a consider-able variation in flower color. ◦ The plant is characterized by herbaceous habit, small seeds and parasitism. ◦ The seeds of S. hermonthica are extremely small, about 0.2 X 0.3mm, weighing about 0.7 μg.
- 38. ◦ They are generally dispersed by water, wind, cattle, and man . ◦ The number of seeds per capsule ranges from 700–1800 depending on the species. ◦ The seeds can remain viable in the field for as long as 14-20 years . ◦ The minimal length of the life cycle of the parasite, from germination to seed production comprises an average of 4 months
- 39. Management Physical methods Hand weeding is an important part of controlling strigaespecially with small infestation .it is necessary to prevent seed production and reinfestation of the soil Mulching – mulches from collophospermum mopane ,Acacia karoo ,Acacia nilotica reduced the incidence of s. asiatica and delayed its emergence and flowering
- 40. Soil fertility management ◦ Use fertilizers that have lots of nitrogen, such as manure and compost @ 120 kg/ha. This keeps crops stronger and more resistant to attack against striga. ◦ The main effects of nitrogen are direct damage to striga seeds and seedlings in soil, a toxic effect of nitrogen on the developing ◦ Other practices like crop rotation Inter cropping Trap cropping
- 41. CHEMICAL CONTROL ◦ Atrazine may be applied at 1.5 – 2.0 kg as pre emergence in maize and sorghum reduces striga ◦ pre planting soil incorporation of fenae/chlorfenac and 2,3,6-TBA are found effective in controlling striga in maize and sugarcane ◦ Application of 2,4-D-5g/ha and foliar application of ammonium chloride in sugarcane crops
- 42. Total stem/holo-stem parasite: They take away food from the host-shoot/stem and do not have any other source of gathering food. Therefore, they are also called “obligate shoot/stem-parasite.” For example, Cuscuta campesstris/chinensis/epilinum (on alfalfa, niger and linseed, respectively). Earlier Cuscuta was the only parasitic genus of the autotrophic family Convolvulaceae. But now-a-days Cuscutaceae, a separate family has come into being for this genus
- 43. Cuscuta
- 44. INTRODUCTION ◦ Cuscuta spp. (dodder) also known as Akashbel or Amarbal, is a parasitic angiosperm belonging to the family Convolvulaceae in older references and Cuscutaceae in the more recent publications. Weber (1986) divided the family Cuscutaceae into two genera i. e. Cuscuta and Grammica, based on the shape of the stigma. The genus Cuscuta is comprised of about 201 species worldwide. Out of these 12 species are reported from India C. campestris and C. reflexa are more common.
- 45. BIOLOGY ◦ In the spring, dodder seeds germinate near the soil surface and send up slender, thread-like twining stems varying in color from pale green to yellow or orange and without any cotyledons (seed leaves). ◦ The slender, leafless, thread-like stem sways or rotates slowly until it touches the stem or leaf of another plant and begins to wind around it . ◦ On a host plant, the dodder stem will immediately form small appendages called haustoria (tiny sucker-like roots), which penetrate the stems or leaves so that dodder can extract its necessary growth requirements.
- 46. ◦ Dodder flowers are numerous, tiny, and whitish to pinkish, and form in small clusters along the stems, generally from May to October depending on the species and location. ◦ Each flower forms a small, globular seedpod with 2 to 4 seeds . The seeds have rough coats and vary in size depending on the species, and may be able to survive over 20 years in the soil
- 47. Host plants ◦ Oilseeds (niger , linseed ) ◦ Pulses (blackgram , greengram , lentil , chickpea) ◦ Fodder crops (lucern, berseem ) ◦ Soybean ◦ Tomato ◦ Potato ◦ onion
- 49. GLOBAL ◦ Europe ◦ American ◦ India INDIA Andhra Pradesh Chhattisgarh Gujarat Orissa West Bengal Madhya Pradesh
- 50. IMPORTANT SPECIES Cuscuta approximata Cuscuta californica Cuscuta epithyma Cuscuta campestris Cuscuta reflexa Cuscuta salina
- 51. Cuscuta approximata Cuscuta californica Cuscuta epithyma
- 52. Cuscuta campestris Cuscuta reflexa Cuscuta salina
- 53. MANAGEMENT Prevention ◦ Seeds of Cuscuta are transported as a contaminant of seed of crops such as alfalfa and clover. Consequently, most Cuscuta problems have originated from human carelessness in transporting and planting contaminated crop seed. ◦ Cuscuta persists and spreads within infested fields through further agricultural activities, by periodic onsite seed production, and because the seed may remain viable for several years in the soil. ◦ As the saying goes, "Prevention is better than cure", the best method of controlling Cuscuta in crops is to prevent its introduction onto a field. Therefore, the crop seeds should completely be free from Cuscuta seeds. Strict seed laws and programmes of seed certification are required to reduce the crop seed contamination by Cuscuta.
- 54. CULTURE CONTROL ◦ Various cultural practices can kill, suppress or delay Cuscuta. Such control methods are inexpensive and can be combined with other methods to develop integrated management systems for Cuscuta. Stale Seedbed Preparation ◦ Under favourable conditions, Cuscuta seeds germinate without host plant and seedlings die after eight days in absence of host. Shallow tillage or spraying of non-selective herbicides (glyphosate or paraquat) after seedling emergence but before sowing of crop reduces the Cuscuta infestation.
- 55. Hand Pulling ◦ Hand pulling is the simplest and most effective method of controlling Cuscuta. In this practice, it is necessary to pull the infested host plant together with the parasite. If flowering and seed set have already occurred, the pulled material must be removed from the field and eventually burnt. Crop Rotation Cuscuta does not parasitize members of the Poaceae. Hence, it can be controlled completely by crop rotation. Without a host plant nearby, Cuscuta seedlings emerge and die. Broadleaf weeds must be controlled in such crops to deprive Cuscuta of all hosts, so that no new Cuscuta seed is produced.
- 56. BIOLOGICAL METHOD ◦ Insects and disease organisms may damage Cuscuta. ◦ Although damage may be severe, it is often incomplete and may develop too slowly to protect the host plant. ◦ In China, the fungus, Colletotrichum gloeosporioides attacks Cuscuta and has been used to control Cuscuta selectively in soybean. ◦ The fungus can be cultured. The spores are collected and applied uniformly to the Cuscuta-infested crop, where they germinate, grow and cause a disease that suppresses Cuscuta
- 57. CHEMICAL CONTROL ◦ Trifluralin applied at 3 kg/ha before shovelling or at 1.5 kg/ha after shovelling effectively controlled the Cuscuta ◦ Fluchloralin 1.5 kg/ha as pre-emergence and 1.0-1.25 kg/ha as pre-plant soil incorporation controlled Cuscuta effectively in blackgram ◦ Pendimethalin 0.5-1.5 kg/ha applied as preemergence controlled Cuscuta in niger , blackgram, linseed, onion, chickpea and lentil
- 58. Partial stem/hemi-stem parasite: Initially they depend upon the host-shoot/stem for their food, but later for becoming green and chlorophyllous, can produce their own food. For example, Loranthus longiflorus is a green colour plant (on mango and other trees)
- 59. LORANTHUS ◦ It is a phanerogamic parasite found mostly in tropics beneath the bark of the trees ◦ It is a partial stem parasite .
- 60. Ecology ◦ Initially it depends upon the host –shoot for their food ,but later for becoming green and chlorophyllus can produce its own food . ◦ Its seeds are dispersed by birds by way of rubbing their beaks on the fresh tree branches
- 61. Biology ◦ This plant having thick leathery leaves arranged oppositely ,spear shaped ◦ Auxillary raceme with 5-6 stamens with single stigma ◦ Fruits are small berry type with single seeded
- 62. Different species of loranthus ◦ Nearly 60 species of Dendrophthoe are present in India . ◦ Loranthus longiflorus var falcatus is the most damaging species . ◦ Loranthus delavayi ◦ Loranthus europaeus ◦ Loranthus macranthus
- 63. Loranthus longiflorus Loranthus delavayi Loranthus europaeus Loranthus macranthus
- 64. Host ◦ Teak ◦ Rosewood ◦ Sandalwood ◦ Mango ◦ Citrus ◦ Tea
- 65. Management Physical method ◦ cutting manually using saw 30 cm before the haustoria attachment . Chemical method ◦ pasting 2,4 – D Na salt 1% in cutted portion ◦ pasting 2,4 – D Na salt 1%+ wipping with Glyphosate 10 ml /litre in cutted portion of loranthus
- 66. Conclusion ◦ Parasitic weeds are among serious pest of crops in both developing and developed countries. They are categorized as root-parasitic or stem parasitic based on parts of plants they attached to it. The life cycle of parasitic weeds is closely associated with their host and, hence information and works target to the host–parasite interaction is crucial to reduce agricultural and any other damages cause. Parasitic weeds have a wide range of host-plants including agricultural crops. They are causing drastic crop yield losses and needs to be managed. So far, few practical and economically sound management practices have been developed to control these weeds. However, these practices couldn’t manage parasitic weeds at required level.
- 67. Thank you