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Weeds - Some important weeds and its management

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This document provides information on several invasive plant species: 1. Mimosa diplotricha is an invasive shrub or climber that smothers other plants through dense growth. It produces toxins harmful to animals. Control methods include mechanical removal and herbicides. 2. Mikania micrantha is a fast-growing vine that forms dense mats, reducing light and nutrients for other plants. It spreads primarily through vegetative means. Control involves mechanical or chemical removal before flowering. 3. Salvinia molesta is an invasive aquatic fern that forms dense mats, reducing oxygen in water bodies and harming native species. Biological control using the salvinia weevil is most effective at

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Weeds
Mimosa diplotricha Common name: Giant sensitive plant, creeping sensitive plant, nila grass. Local name: Anathottawadi Taxonomic position: Division: Magnoliophyta Class: Magnoliopsida, Order: Fabales Distribution: South and South -East Asia, Pacific islands, Northern Australia, South and Central America, Africa, Nigeria and France
Altitude: 0-2000m In evergreen and semi-evergreen forests, infestation is limited to the fringes of the forest wherever the canopy is open due to disturbance The weed is heliophytic in adaptation and cannot grow under a closed canopy It is drought-resistant but senesce leaves during dry conditions.
Fast growing, erect shrub and a scrambling climber Annual plant Leaves are bright green, feathery, alternate, each leaf with about 20 pairs of small leaflets Stem is four-angled, woody at the base, re-curved thorns (3-6mm long) Inflorescence: clustered fluffy ball, pale pink colour, corolla is gamopetalous
Weeds - Some important weeds and its management
There are twice as many stamens as petals The pods are clustered, 10 - 35 mm long and 6 mm wide, linear, flat, clothed with small prickles, splitting transversely into one-seeded sections at the groves Seeds are flat, ovate, spiny Seed production is in the range of 8,000 - 12,000 per m2
Weeds - Some important weeds and its management
Weeds - Some important weeds and its management
The weight of 1,000 seeds is around 6 gm Flowering: August to February Seed setting: September to February Seed dispersal: running water, carried in animal fur, clothing, vehicles Seeds are known to lie dormant up to 50 years Scrambles vigorously over other plants, It smothers and kills indigenous flora.
In India, Mimosa smothers other invasive weeds such as Chromolaena odorata and Mikania micrantha Threat and damage Thick growth of Mimosa prevents the regeneration, reproduction and growth of indigenous species in all infested areas
Mimosa over growing Mikania
Mimosa smothering coconut palm
All parts of the plant are toxic to herbivores if ingested It produces a toxin (mimosin - a non-protein amino acid), which can cause vascular endothelial damage, necroses of the heart and liver and anemia in cattle. The tangled and thorny growth of Mimosa hampers movement and access to food and other resources for wild animals
Uses It is used as nitrogen fixing cover crop and green manure in several countries in the Asia-Pacific region.
Control Measures Mechanical: Uprooting and burning, grubbing and slashing are the most common methods Uprooting is the most efficient method to control the weed. This should be done at least twice a year to achieve a satisfactory level of control The first uprooting may be done before flowering and seed setting and the second soon after the first showers when seedlings emerge from seeds arriving from other sources. Slashing is not advisable since the weed can easily re-generate from the cut stumps
Chemical Use of glyphosate (0.75 kg), paraquat (0.5 kg), diuron (2 - 4 kg) The applications are to be done before the onset of flowering and fruiting
Biological Heteropsylla spinulosa: causes growing tip distortion and reduces seed production Corynespora cassiicola: stem spot, defoliation and dieback Psygida walkeri : A moth which feeds on the leaves, flower buds, tender seedpods and tender stems
Sickle weeding
Mikania micrantha
Taxonomic position: Division: Magnoliophyta Class: Magnoliopsida, Order: Asterales Family: Asteraceae Common name: American rope, Chinese creeper, mile-a- minute weed Local names: American vally, silk vally, kaipu vally, Dhritharashtra pacha (Kerala)
A perennial twining herb with 5-ribbed branches Leaves are opposite Flowering : August January Fruit setting starts 17-21 days after flowering (Sept- Feb) A single stalk can produce 20,000 - 40,000 mature seeds in one season Dispersal of the seeds occurs between October and April The mean number of seeds per mg is 108 賊 12
The plants can grow vegetatively from the nodes and very small segments of the stem Growth of young plants is extremely fast (8 - 9 cm in 24 hours) Seed dispersal: wind, animals and water currents The germination percentage of seeds is very low (8-12%) Light, water, soil nutrients and fire affect the germination of seeds The main mode of propagation is vegetative
Habitat: Wet places, forest borders and clearings, along the banks of streams and rivers, roadsides and railway tracks, in pastures, forest plantations, agricultural and agro - forestry systems, open disturbed areas and barren lands Grows luxuriantly on leached and nutrient poor sandy loam to clayey soils Produce a large quantity of biomass in a single life span (C3 plant).
Positive response to high potassium levels in soils Heavy grazing and browsing promotes the spread of Mikania into new ecosystems The weed cannot tolerate shade and hence fails to penetrate undisturbed natural forest areas competes with trees and other crop plants for soil nutrients, water and sunlight The weed can reduce light interception by covering the canopy of trees The adverse effect of Mikania on crops and soil properties is through the production of phenolic and flavanoid compounds
Natural Forest: reduction in species richness, habitat destruction, Species monopolization and new microsite formation The weed renders collection of non-wood products (e.g., reed extraction) from natural forests less profitable, since heavy overgrowth of the weed disrupts collection.
Seedling of Mikania Branches with inflorescence
Mikania vine with mature seeds Mikania seeds bearing pappus
Mikania growing along the banks of water bodies Mikania smothering vegetation in a degraded natural forest Mikania overgrowing banana
Control measures Mechanical: Sickle weeding, uprooting and digging Sickle weeding before flowering and seed setting gives temporary control. But quick re-growth from cut stumps frustrates this method Uprooting during the initial stages of growth (before flowering and fruiting) is the most effective mechanical control method. The slash and burn technique is also practiced widely. the weed stock may survive burning and produce young shoots in a couple of months Mechanical control method is very labour intensive and uneconomical.
Sickle weeding of Mikania Herbicidal application on Mikania
Chemical : Both pre-emergent and post-emergent herbicides are generally used for Mikania control Pre-emergence application of oxyflourfen (0.06 kg ha-1) + paraquat (0.24 kg ha1) is reported to be effective if applied before flowering or seed setting. Glyphosate (0.5 to 4.5 kg ha1 or 0.75 to 8 l ha-1) especially in forest plantations Diuron at the rate of 1-2 kg ha1, triclopyr + picloram (commercial name Grazon DS) @ 1.75 l ha-1 and triclopyr (commercial name Garlon 600) @ 500 ml ha-1
Biological: A microcyclic rust Puccinia spegazzinii Leaf and petiole infection on Mikania caused by Puccinia spegazzinii
Salvinia molesta
A floating aquatic fern that thrives in slow-moving, nutrient- rich, warm, freshwater. A rapidly growing competitive plant Grows well in water temperatures around 2030 C. Common name: African payal, aquarium watermoss Dispersed through water bodies Form dense vegetation mats that reduce water-flow and lower the light and oxygen levels in the water.
Invasions can alter wetland ecosystems and cause wetland habitat loss It produces a horizontal rhizome (that lies below the water surface) and two types of fronds (buoyant and submerged). The surface of each fronds is covered with long, stiff, water- repellent hairs. Believed to be a sterile hybrid. It does not produce flowers reproducing only by vegetative means Reproduction occurs when mature plants produce buds at the stem node (the join between sections of the stem) which develop to form daughter plants.
Salvinia prefers warmer temperatures and, because its frost sensitive, it produces little growth in winter. When summer temperatures rise, salvinia increases its vegetative growth. Threats: High rates of transpiration through the leaves during summer can cause up to four times more water to be lost than is normally lost through water surface evaporation. Reduce the infiltration of sunlight necessary for native plant growth
Heavy weed cover also prevents the exchange of air that normally occurs on an open-water surface. As the plant dies and decomposes, oxygen is removed from the water, causing water pollution and stagnation. This stagnation affects water quality, and may result in the death of aquatic animals
Control measures Biological control Cyrtobagous salviniae (salvinia weevil) The salvinia weevil is 23 mm long and dark brown to black. It is most effective when air temperatures are 2735C and plant nitrogen levels are high The salvinia weevil larvae feed on the new growth buds and tunnel into the rhizome. Tunnelling weakens the salvinia, reducing its ability to grow and compensate for bud loss. In the initial stages of weevil damage some salvinia leaves will turn brown. As the salvinia weevils continue their control efforts, the whole mat will turn brown, sink underwater and finally decompose the time taken for weevils to control salvinia varies from 13 years.
Cyrtobagous salviniae
Mechanical control: Removal of salvinia by hand or machine is a practical control method often used for small areas Burial is the quickest means of disposal Chemical control: Calcium dodecylbenzene sulphonate (1 part in 19 parts of kerosene) Orange oil + sufactant (1 litre/100 litre of water) 360 g/L Gyphosate as isopropylamine and mono ammonium salts Diquat (50-100 L/ha)
Lantana camara
Taxonomic position: Division: Magnoliophyta Class: Magnoliopsida, Order: Lamiales Family: Verbenaceae Common names: Sleeper weed, lantana, wild sage
A low, erect or subscandent, vigorous shrub which can grow to 2 - 4 meters in height The leaf is ovate or ovate oblong, 2 - 10 cm long and 2 - 6 cm wide, arranged in opposite pairs. Leaves are bright green, rough, finely hairy, with serrate margins and emit a pungent odour when crushed Flower heads contain 20 - 40 flowers
Colour varies from white, cream or yellow to orange pink, purple and red Flowering occurs between August and March, or all year round if adequate moisture and light are available Pollinators include lepidopteran species and thrips. The fruit is a greenish blue-black colour, 5 - 7 mm in diameter, drupaceous, shining, with two nutlets
Seed setting takes place between September to May with 1 - 20 seeds on each flower head. Mature plants produce up to 12,000 seeds annually Seed germination occurs when sufficient moisture is present; germination is reduced by low light conditions The root system is very strong with a main taproot and a mat of many shallow side roots
Fruits of Lantana Birds aid seed dispersal
Fruit dispersal is through frugivorous birds, fox and rodents Seeds are capable of surviving the hottest fires grows best in open, un-shaded conditions such as wastelands, the edges of rain forests, on beachfronts, in agricultural areas, grasslands, riparian zones, scrub/shrub lands, urban areas, wetlands and forests recovering from fire or logging. Roadsides, railway tracks and canal banks are favored by the species The plant is found at altitudes from sea level to 2,000 m and can thrive very well under rainfall ranging from 750 to 5000 mm per annum
Where natural forests have been disturbed through logging creating gaps, Lantana encroaches in the gaps. As the density of Lantana in natural forest areas increases, species richness decreases. Layering is a form of vegetative reproduction in Lantana where the stem send roots into soil, allowing it to quickly form very dense stands and spread short distances.
Threat and damage Threatens natural habitats and native flora and fauna. The allelopathic qualities of Lantana reduce the vigour of native plant species and limits their productivity In dense stands of Lantana, the capacity of the soil to absorb rain is lower than under good grass cover. This could potentially increase the amount of run-off and the subsequent risk of soil erosion Lantana has been implicated in poisoning of a number of animals including cattle, buffalo, sheep and goats since its leaves and seeds contain the toxic triterpenoids, Lantadene A and Lantadene B
Control Measures Mechanical control Stickraking, bulldozing, ploughing , grubbing, Hand cutting using brush cutters, hand pulling, chain pulling and flame weeding Re-growth will be imminent if the rootstock is not removed while weeding not recommended in areas susceptible to erosion. Fire is often used prior to mechanical or herbicidal control to improve their effectiveness or as a follow-up to such methods
Fire itself can provide some control when used under the right conditions, especially if the fires are hot and the Lantana is actively growing. Re-vegetation of a treated site by planting trees or encouraging naturally occurring seedlings is a key component of a Lantana management program.
Manual cutting of Lantana Control of Lantana using fire Chemical control of Lantana Teleonemia scrupulosa
Chemical control Use of fluroxypyr @ 0.5 to 1 liter / 100 l water, Glyphosate @ 1l / 100 l water, triclopyr @ 1l / 60 l of water and Grazon DS (300 g/l triclopyr + 100 g/l picloram) @ of 350 ml/100 l water per ha is recommended. Post emergence application of glyphosate (2 kg ha-1) may provide good control. Applications are to be done When there is good soil moisture and during the active growing period, either in the morning or late in the afternoon.
Biological control Not successful in controlling the weed effectively The sap-sucking bug, Teleonemia scrupulosa (Hemiptera), Leaf mining beetles, Octotoma scabripennis (Coleoptera) and Uroplata girardi (Coleoptera) and the seed feeding fly, Ophiomyia lantanae (Diptera)
Chromolaena odorata Belongs to family: Asteraceae A scrambling perennial shrub, with straight, pithy, brittle stems three-veined, ovate-triangular leaves placed oppositely shallow, fibrous root system In open-land situations, C. odorata grows to 23min height, but it can reach up to 510mwhen supported by other vegetation
Plants grow vigorously throughout the wet season and flowering is initiated by a decrease in both day length and rainfall Flowering peaks in DecemberJanuary in the northern hemisphere and JuneJuly in the southern hemisphere fertile seed is produced without pollination, as the species is apomictic Seeds are dispersed by wind, as well as via animal fur, clothing, and vehicles
Most seed loses its viability after a year Forest gaps that naturally develop through tree-fall are colonized rapidly by C. odorata, suppressing the recruitment of trees In dry season it is a fire hazard, the dry pithy stems and leaves are rich in oils and burn readily
Control measures Mechanical: Slashing and burning followed by frequent hoeing and uprooting Biological control: Using Pareuchaetes pseudoinsulata Chemical control: Glyphospate( 360 g/l) @ 100ml/10l of water, Triclopyrester (480g/l) @ 37.5ml/10l of water, Imazapyr (100g/l) @ 200ml/ 10L of water
Cassia spectabilis Taxonomic position Kingdom :Plantae Phylum :Magnoliophyta Class :Magnoliopsida Subclass :Rosidae Order: Fabales Family: Fabaceae A small, rounded deciduous tree, 7-10 m tall, with a spreading crown Leaves alternate, compound, with 4-15 pairs of leaflets Leaflets narrowly elliptic Base rounded, apex, acute, margin entire Inflorescence large, terminal, lateral, leafy panicles
Flowers: fragrant, composed of 5 rounded hairy bracts, which are ovate, sepals orange-yellow, unequal, ovate to suborbicular; Petals yellow Fruit cylindrical or flattened pods Orthodox seed Seeds can be stored for up to 2 years There are about 39000 seeds/kg
Control Measures Mechanical: Cutting or girdling Removing seed pods from the forest immediately after they fall to the ground before seeds Chemical control: Hack and squirt method or bark injection (Hacks a small cuts in the trunk of target trees and squirts an herbicide solution into the cut.) Herbicides used: Arsenal AC (10%), Garlon 3A and 2-4,D Amine
Parthenium hysterophorus Family: Asteracea Common name: altamisa, carrot grass, bitter weed, star weed, white top, wild feverfew, the Scourge of India and congress grass An aggressive annual herbaceous weed Often spotted on abandoned lands, developing residential colonies around the towns, railway tracks, roads, drainage and irrigation canals, etc.
A single plant can produce 10,000 to 15,000 viable seeds Threats: Health hazards to humans and livestock Reducing agricultural and pasture productivity Biodiversity loss due Control measures Mechanical control: Hand hoeing Chemical control: 2,4- D
Biological control: Not succesful the insect consumes only the foliage of the weed , the flowers and seeds, which are the main source of its dissemination, remain unaffected.
Ficus benghalensis Family: Moraceae they are capable of germinating in native host trees, where they grow as epiphytes, eventually destroying their hosts (engulfing) Wide spreading banyan with copious aerial roots Leaves broadly ovate, obtuse, the base cordate Figs paired, sessile, maturing orange to red
Control measures Physical control: small seedlings on the ground or as epiphytes can be pulled out. Chemical control: particularly sensitive to triclopyr herbicides Biological control: Using natural enemies of the pollinators
Ficus religiosa Family: Moraceae Local names: wisdom tree, ficus,peepal,bodhi tree Irregularly-shaped tree, with wide-spreading branches , without aerial roots from the branches The trunk is regularly shaped, often with low buttresses
Leaves alternate, spirally arranged and broadly ovate, glossy, coriaceous (leathery), dark green leaves Flowers axillary sessile, unisexual flowers in February and fruits in May to June New leaves appear in April in India The pollinator wasp for Ficus religiosa is Blastophaga quadraticeps When seeds are dropped on other trees, they germinate. The seedlings rely on the host plant only for anchorage as F. religiosa does not parasitize on other plants. They derive their nutrition from the air and rainfall, until the roots reach the ground

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Weeds - Some important weeds and its management

  • 2. Mimosa diplotricha Common name: Giant sensitive plant, creeping sensitive plant, nila grass. Local name: Anathottawadi Taxonomic position: Division: Magnoliophyta Class: Magnoliopsida, Order: Fabales Distribution: South and South -East Asia, Pacific islands, Northern Australia, South and Central America, Africa, Nigeria and France
  • 3. Altitude: 0-2000m In evergreen and semi-evergreen forests, infestation is limited to the fringes of the forest wherever the canopy is open due to disturbance The weed is heliophytic in adaptation and cannot grow under a closed canopy It is drought-resistant but senesce leaves during dry conditions.
  • 4. Fast growing, erect shrub and a scrambling climber Annual plant Leaves are bright green, feathery, alternate, each leaf with about 20 pairs of small leaflets Stem is four-angled, woody at the base, re-curved thorns (3-6mm long) Inflorescence: clustered fluffy ball, pale pink colour, corolla is gamopetalous
  • 6. There are twice as many stamens as petals The pods are clustered, 10 - 35 mm long and 6 mm wide, linear, flat, clothed with small prickles, splitting transversely into one-seeded sections at the groves Seeds are flat, ovate, spiny Seed production is in the range of 8,000 - 12,000 per m2
  • 9. The weight of 1,000 seeds is around 6 gm Flowering: August to February Seed setting: September to February Seed dispersal: running water, carried in animal fur, clothing, vehicles Seeds are known to lie dormant up to 50 years Scrambles vigorously over other plants, It smothers and kills indigenous flora.
  • 10. In India, Mimosa smothers other invasive weeds such as Chromolaena odorata and Mikania micrantha Threat and damage Thick growth of Mimosa prevents the regeneration, reproduction and growth of indigenous species in all infested areas
  • 13. All parts of the plant are toxic to herbivores if ingested It produces a toxin (mimosin - a non-protein amino acid), which can cause vascular endothelial damage, necroses of the heart and liver and anemia in cattle. The tangled and thorny growth of Mimosa hampers movement and access to food and other resources for wild animals
  • 14. Uses It is used as nitrogen fixing cover crop and green manure in several countries in the Asia-Pacific region.
  • 15. Control Measures Mechanical: Uprooting and burning, grubbing and slashing are the most common methods Uprooting is the most efficient method to control the weed. This should be done at least twice a year to achieve a satisfactory level of control The first uprooting may be done before flowering and seed setting and the second soon after the first showers when seedlings emerge from seeds arriving from other sources. Slashing is not advisable since the weed can easily re-generate from the cut stumps
  • 16. Chemical Use of glyphosate (0.75 kg), paraquat (0.5 kg), diuron (2 - 4 kg) The applications are to be done before the onset of flowering and fruiting
  • 17. Biological Heteropsylla spinulosa: causes growing tip distortion and reduces seed production Corynespora cassiicola: stem spot, defoliation and dieback Psygida walkeri : A moth which feeds on the leaves, flower buds, tender seedpods and tender stems
  • 20. Taxonomic position: Division: Magnoliophyta Class: Magnoliopsida, Order: Asterales Family: Asteraceae Common name: American rope, Chinese creeper, mile-a- minute weed Local names: American vally, silk vally, kaipu vally, Dhritharashtra pacha (Kerala)
  • 21. A perennial twining herb with 5-ribbed branches Leaves are opposite Flowering : August January Fruit setting starts 17-21 days after flowering (Sept- Feb) A single stalk can produce 20,000 - 40,000 mature seeds in one season Dispersal of the seeds occurs between October and April The mean number of seeds per mg is 108 賊 12
  • 22. The plants can grow vegetatively from the nodes and very small segments of the stem Growth of young plants is extremely fast (8 - 9 cm in 24 hours) Seed dispersal: wind, animals and water currents The germination percentage of seeds is very low (8-12%) Light, water, soil nutrients and fire affect the germination of seeds The main mode of propagation is vegetative
  • 23. Habitat: Wet places, forest borders and clearings, along the banks of streams and rivers, roadsides and railway tracks, in pastures, forest plantations, agricultural and agro - forestry systems, open disturbed areas and barren lands Grows luxuriantly on leached and nutrient poor sandy loam to clayey soils Produce a large quantity of biomass in a single life span (C3 plant).
  • 24. Positive response to high potassium levels in soils Heavy grazing and browsing promotes the spread of Mikania into new ecosystems The weed cannot tolerate shade and hence fails to penetrate undisturbed natural forest areas competes with trees and other crop plants for soil nutrients, water and sunlight The weed can reduce light interception by covering the canopy of trees The adverse effect of Mikania on crops and soil properties is through the production of phenolic and flavanoid compounds
  • 25. Natural Forest: reduction in species richness, habitat destruction, Species monopolization and new microsite formation The weed renders collection of non-wood products (e.g., reed extraction) from natural forests less profitable, since heavy overgrowth of the weed disrupts collection.
  • 26. Seedling of Mikania Branches with inflorescence
  • 27. Mikania vine with mature seeds Mikania seeds bearing pappus
  • 28. Mikania growing along the banks of water bodies Mikania smothering vegetation in a degraded natural forest Mikania overgrowing banana
  • 29. Control measures Mechanical: Sickle weeding, uprooting and digging Sickle weeding before flowering and seed setting gives temporary control. But quick re-growth from cut stumps frustrates this method Uprooting during the initial stages of growth (before flowering and fruiting) is the most effective mechanical control method. The slash and burn technique is also practiced widely. the weed stock may survive burning and produce young shoots in a couple of months Mechanical control method is very labour intensive and uneconomical.
  • 30. Sickle weeding of Mikania Herbicidal application on Mikania
  • 31. Chemical : Both pre-emergent and post-emergent herbicides are generally used for Mikania control Pre-emergence application of oxyflourfen (0.06 kg ha-1) + paraquat (0.24 kg ha1) is reported to be effective if applied before flowering or seed setting. Glyphosate (0.5 to 4.5 kg ha1 or 0.75 to 8 l ha-1) especially in forest plantations Diuron at the rate of 1-2 kg ha1, triclopyr + picloram (commercial name Grazon DS) @ 1.75 l ha-1 and triclopyr (commercial name Garlon 600) @ 500 ml ha-1
  • 32. Biological: A microcyclic rust Puccinia spegazzinii Leaf and petiole infection on Mikania caused by Puccinia spegazzinii
  • 34. A floating aquatic fern that thrives in slow-moving, nutrient- rich, warm, freshwater. A rapidly growing competitive plant Grows well in water temperatures around 2030 C. Common name: African payal, aquarium watermoss Dispersed through water bodies Form dense vegetation mats that reduce water-flow and lower the light and oxygen levels in the water.
  • 35. Invasions can alter wetland ecosystems and cause wetland habitat loss It produces a horizontal rhizome (that lies below the water surface) and two types of fronds (buoyant and submerged). The surface of each fronds is covered with long, stiff, water- repellent hairs. Believed to be a sterile hybrid. It does not produce flowers reproducing only by vegetative means Reproduction occurs when mature plants produce buds at the stem node (the join between sections of the stem) which develop to form daughter plants.
  • 36. Salvinia prefers warmer temperatures and, because its frost sensitive, it produces little growth in winter. When summer temperatures rise, salvinia increases its vegetative growth. Threats: High rates of transpiration through the leaves during summer can cause up to four times more water to be lost than is normally lost through water surface evaporation. Reduce the infiltration of sunlight necessary for native plant growth
  • 37. Heavy weed cover also prevents the exchange of air that normally occurs on an open-water surface. As the plant dies and decomposes, oxygen is removed from the water, causing water pollution and stagnation. This stagnation affects water quality, and may result in the death of aquatic animals
  • 38. Control measures Biological control Cyrtobagous salviniae (salvinia weevil) The salvinia weevil is 23 mm long and dark brown to black. It is most effective when air temperatures are 2735C and plant nitrogen levels are high The salvinia weevil larvae feed on the new growth buds and tunnel into the rhizome. Tunnelling weakens the salvinia, reducing its ability to grow and compensate for bud loss. In the initial stages of weevil damage some salvinia leaves will turn brown. As the salvinia weevils continue their control efforts, the whole mat will turn brown, sink underwater and finally decompose the time taken for weevils to control salvinia varies from 13 years.
  • 40. Mechanical control: Removal of salvinia by hand or machine is a practical control method often used for small areas Burial is the quickest means of disposal Chemical control: Calcium dodecylbenzene sulphonate (1 part in 19 parts of kerosene) Orange oil + sufactant (1 litre/100 litre of water) 360 g/L Gyphosate as isopropylamine and mono ammonium salts Diquat (50-100 L/ha)
  • 42. Taxonomic position: Division: Magnoliophyta Class: Magnoliopsida, Order: Lamiales Family: Verbenaceae Common names: Sleeper weed, lantana, wild sage
  • 43. A low, erect or subscandent, vigorous shrub which can grow to 2 - 4 meters in height The leaf is ovate or ovate oblong, 2 - 10 cm long and 2 - 6 cm wide, arranged in opposite pairs. Leaves are bright green, rough, finely hairy, with serrate margins and emit a pungent odour when crushed Flower heads contain 20 - 40 flowers
  • 44. Colour varies from white, cream or yellow to orange pink, purple and red Flowering occurs between August and March, or all year round if adequate moisture and light are available Pollinators include lepidopteran species and thrips. The fruit is a greenish blue-black colour, 5 - 7 mm in diameter, drupaceous, shining, with two nutlets
  • 45. Seed setting takes place between September to May with 1 - 20 seeds on each flower head. Mature plants produce up to 12,000 seeds annually Seed germination occurs when sufficient moisture is present; germination is reduced by low light conditions The root system is very strong with a main taproot and a mat of many shallow side roots
  • 46. Fruits of Lantana Birds aid seed dispersal
  • 47. Fruit dispersal is through frugivorous birds, fox and rodents Seeds are capable of surviving the hottest fires grows best in open, un-shaded conditions such as wastelands, the edges of rain forests, on beachfronts, in agricultural areas, grasslands, riparian zones, scrub/shrub lands, urban areas, wetlands and forests recovering from fire or logging. Roadsides, railway tracks and canal banks are favored by the species The plant is found at altitudes from sea level to 2,000 m and can thrive very well under rainfall ranging from 750 to 5000 mm per annum
  • 48. Where natural forests have been disturbed through logging creating gaps, Lantana encroaches in the gaps. As the density of Lantana in natural forest areas increases, species richness decreases. Layering is a form of vegetative reproduction in Lantana where the stem send roots into soil, allowing it to quickly form very dense stands and spread short distances.
  • 49. Threat and damage Threatens natural habitats and native flora and fauna. The allelopathic qualities of Lantana reduce the vigour of native plant species and limits their productivity In dense stands of Lantana, the capacity of the soil to absorb rain is lower than under good grass cover. This could potentially increase the amount of run-off and the subsequent risk of soil erosion Lantana has been implicated in poisoning of a number of animals including cattle, buffalo, sheep and goats since its leaves and seeds contain the toxic triterpenoids, Lantadene A and Lantadene B
  • 50. Control Measures Mechanical control Stickraking, bulldozing, ploughing , grubbing, Hand cutting using brush cutters, hand pulling, chain pulling and flame weeding Re-growth will be imminent if the rootstock is not removed while weeding not recommended in areas susceptible to erosion. Fire is often used prior to mechanical or herbicidal control to improve their effectiveness or as a follow-up to such methods
  • 51. Fire itself can provide some control when used under the right conditions, especially if the fires are hot and the Lantana is actively growing. Re-vegetation of a treated site by planting trees or encouraging naturally occurring seedlings is a key component of a Lantana management program.
  • 52. Manual cutting of Lantana Control of Lantana using fire Chemical control of Lantana Teleonemia scrupulosa
  • 53. Chemical control Use of fluroxypyr @ 0.5 to 1 liter / 100 l water, Glyphosate @ 1l / 100 l water, triclopyr @ 1l / 60 l of water and Grazon DS (300 g/l triclopyr + 100 g/l picloram) @ of 350 ml/100 l water per ha is recommended. Post emergence application of glyphosate (2 kg ha-1) may provide good control. Applications are to be done When there is good soil moisture and during the active growing period, either in the morning or late in the afternoon.
  • 54. Biological control Not successful in controlling the weed effectively The sap-sucking bug, Teleonemia scrupulosa (Hemiptera), Leaf mining beetles, Octotoma scabripennis (Coleoptera) and Uroplata girardi (Coleoptera) and the seed feeding fly, Ophiomyia lantanae (Diptera)
  • 55. Chromolaena odorata Belongs to family: Asteraceae A scrambling perennial shrub, with straight, pithy, brittle stems three-veined, ovate-triangular leaves placed oppositely shallow, fibrous root system In open-land situations, C. odorata grows to 23min height, but it can reach up to 510mwhen supported by other vegetation
  • 56. Plants grow vigorously throughout the wet season and flowering is initiated by a decrease in both day length and rainfall Flowering peaks in DecemberJanuary in the northern hemisphere and JuneJuly in the southern hemisphere fertile seed is produced without pollination, as the species is apomictic Seeds are dispersed by wind, as well as via animal fur, clothing, and vehicles
  • 57. Most seed loses its viability after a year Forest gaps that naturally develop through tree-fall are colonized rapidly by C. odorata, suppressing the recruitment of trees In dry season it is a fire hazard, the dry pithy stems and leaves are rich in oils and burn readily
  • 58. Control measures Mechanical: Slashing and burning followed by frequent hoeing and uprooting Biological control: Using Pareuchaetes pseudoinsulata Chemical control: Glyphospate( 360 g/l) @ 100ml/10l of water, Triclopyrester (480g/l) @ 37.5ml/10l of water, Imazapyr (100g/l) @ 200ml/ 10L of water
  • 59. Cassia spectabilis Taxonomic position Kingdom :Plantae Phylum :Magnoliophyta Class :Magnoliopsida Subclass :Rosidae Order: Fabales Family: Fabaceae A small, rounded deciduous tree, 7-10 m tall, with a spreading crown Leaves alternate, compound, with 4-15 pairs of leaflets Leaflets narrowly elliptic Base rounded, apex, acute, margin entire Inflorescence large, terminal, lateral, leafy panicles
  • 60. Flowers: fragrant, composed of 5 rounded hairy bracts, which are ovate, sepals orange-yellow, unequal, ovate to suborbicular; Petals yellow Fruit cylindrical or flattened pods Orthodox seed Seeds can be stored for up to 2 years There are about 39000 seeds/kg
  • 61. Control Measures Mechanical: Cutting or girdling Removing seed pods from the forest immediately after they fall to the ground before seeds Chemical control: Hack and squirt method or bark injection (Hacks a small cuts in the trunk of target trees and squirts an herbicide solution into the cut.) Herbicides used: Arsenal AC (10%), Garlon 3A and 2-4,D Amine
  • 62. Parthenium hysterophorus Family: Asteracea Common name: altamisa, carrot grass, bitter weed, star weed, white top, wild feverfew, the Scourge of India and congress grass An aggressive annual herbaceous weed Often spotted on abandoned lands, developing residential colonies around the towns, railway tracks, roads, drainage and irrigation canals, etc.
  • 63. A single plant can produce 10,000 to 15,000 viable seeds Threats: Health hazards to humans and livestock Reducing agricultural and pasture productivity Biodiversity loss due Control measures Mechanical control: Hand hoeing Chemical control: 2,4- D
  • 64. Biological control: Not succesful the insect consumes only the foliage of the weed , the flowers and seeds, which are the main source of its dissemination, remain unaffected.
  • 65. Ficus benghalensis Family: Moraceae they are capable of germinating in native host trees, where they grow as epiphytes, eventually destroying their hosts (engulfing) Wide spreading banyan with copious aerial roots Leaves broadly ovate, obtuse, the base cordate Figs paired, sessile, maturing orange to red
  • 66. Control measures Physical control: small seedlings on the ground or as epiphytes can be pulled out. Chemical control: particularly sensitive to triclopyr herbicides Biological control: Using natural enemies of the pollinators
  • 67. Ficus religiosa Family: Moraceae Local names: wisdom tree, ficus,peepal,bodhi tree Irregularly-shaped tree, with wide-spreading branches , without aerial roots from the branches The trunk is regularly shaped, often with low buttresses
  • 68. Leaves alternate, spirally arranged and broadly ovate, glossy, coriaceous (leathery), dark green leaves Flowers axillary sessile, unisexual flowers in February and fruits in May to June New leaves appear in April in India The pollinator wasp for Ficus religiosa is Blastophaga quadraticeps When seeds are dropped on other trees, they germinate. The seedlings rely on the host plant only for anchorage as F. religiosa does not parasitize on other plants. They derive their nutrition from the air and rainfall, until the roots reach the ground