Unlocking Exploration: Self-Motivated Agents Thrive on Memory-Driven Curiosity
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1. Name of the Student : Ranjitha .N.
ID No. : UHS15PGM664
Course : HPP 507
Degree Programme and Subject : M.Sc., (Hort.)
Plant pathology
College : College of Horticulture, Bengaluru.
4. INTRODUCTION
• Chilli (Capsicum annum and Capsicum fruticence) belongs to the family
solanaceae and genus capsicum.
• Leading state AP (25% of the total area and over 40-50%of the total world
production).
• Chilli is grown in tropical as well as in temperate zones.
• It is widely used in the manufacture of curry powder, curry paste and all kinds of
pickles and preparing soups and salads etc, the pungency in chillies due to an
alkaloid capsisin.
• A major contributor to this lower productivity are various diseases ,which are
damping off, anthracnose ,bacterial leaf spot and leaf curl of chillies
7. • The diseases prevently occurs and greatly damages many plants such as chilli
,tomato , brinjal belonging to solanaceae family.
SYMPTOM:
• Symptom of this diseases generally manifest into two stages pre emergence and
post emergence stages.
• Pre emergence stage symptom occur when the seeds are still to grow in soil or the
developing seedlings are still to come over the soil surface.
• Seed generally fail to germinate ,become soft and mushy then turn to brown ,
shrink and finally degenerate.
8. • Post emergence symptom occur when the seedling are out on the surface of the
soil.
• The pathogen attack the young tissues at or below the ground level. The infected
tissues become discoloured ,water soaked and soon collapse.
• The infected part of the seedlings looks much thinner softer than healthy part.
• The pathogen continues to invade the seedling tissues after it has fallen on the
ground and seedling quickly withers and dies.
11. ETIOLOGY
• Diseases caused by pythium spp (Pythium ultimum ,Pythium debaryanum
,Pythium aphanidermatum)
• The mycelium is colourless ,slender , coenocytic ,profusely branching and rapid
growing.
• Mycelium produces terminal or intercalary sporangia, which are globose to oval.
• The zoospores are produced within a vesicle.
• Zoospores are reniform and biflagellate.
• The size of the resting zoospores is upto 8µm in diameter.
12. • Sexual spores are oospores ,the oospore develops into a smooth and thick walled
oospore. It measures about 12-20µm.
• Primary source :oospores in soil or plant debries.
• Secondary source: zoospores through irrigation water.
.
13. Epidemology:
• High soil moisture
• higher soil temperature.
• The disease is further aggravated in ill-aerated soils with poor drainage
having thick stand of the seedlings
14. CULTURAL PRACTICES:
• Field sanitation:
1. Collect and burn the infected plant debries of chilli.
2. Destroy self-grown solanaceous plant, other volunteer plants from the field and
surrounding areas.
15. Deep ploughing:
1. Post harvest ,plough the left over inoculum deep into the soil
2. Practice summer ploughing
3. solarization
Cropping system:
• Follow crop rotation.
• Avoid growing of two solanaceous crop in a single year in and around the same
field.
Seed:
• Use certified seed of varieties for different areas.
16. 2.Use Seeds obtained from a diseases free crop.
3. Seed treatment with Bavistin or Agrosan GN @2g/kg of seeds
Sowing:
• Thin sowing to avoid crowding ,
• light sandy soils for nurseries or use of pure time sand dust mixture for raising
the seedlings .
• Under well drained conditions seedling can be transplanted into loamy soil also.
17. NUTRITION
Apply fully decomposed FYM or compost to balance the nutrient supply .
Add NPK fertilizer where necessary to make up for a 90:60:60 kg/ha.
Thinning and weeding:
• Remove the weeds .
• Rouge out the mixture and stay diseased plant as their serve as foci of infection.
18. IRRIGATION
• Provide only need based light irrigations
VARIETAL:
• Resistant/ tolerant genotypes against disease G-5,Pusa Jwala ,PantC-1 ,NP-46
19. CHEMICAL:
• seed treatment such as Thiram or captan @ 3g/kg of seeds for the
better control of damping off .
• Soil drenching with Captan or Thiram @0.2-0.5%
20. • Also called dieback or ripe fruit rot of chillies.
• The disease is one of the most serious disease of chilli . It occurs throughout India
SYMPTOMS:
• The pathogen cause two different types of symptoms on two different parts of the
host.
• Called die back because the disease cause necrosis of the tender twigs from the tip
back wards.
• The entire branch of the plant may wither away.
21. • The twigs are water soaked to brown , become grayish white or straw coloured in
advance stage of the disease.
• Large number of black dots called acervuli are formed on the affected twigs.
• The disease usually occurs on mature fruits as circular to elliptical sunken black
margins and marketed with concentric rings.
• Badly diseasd fruits turn straw coloured from normal red.
• On this discoloured area ,numerous black dots are present. The diseased fruit may
drop off prematurely.
24. ETIOLOGY
• Disease is caused by Colletotrichum capsici .
• Mycelium septate ,colourless and inter and intracellular.
• Hyphae develop the fruiting body called acervulli.
• Acervulli consists of septate ,conidiophore and conidia.
• The setae are septate and dark brown with light brown tip.
• Conidiophores are mostly clubshaped ,under- branched, small and unicellular.
• The conidia are hyaline ,unicellular ,sickle shaped and are produced singhly at the
tip of the conidiophores.
25. Primary source: Infected seeds and diseased crop debries .
Secondary source :Conidia dispersed by rain splash and wind .
It also infect tomato ,potato ,brinjal ,wild bringal are the other hosts.
Epidemology:
• Ideal temperature is 28-30°.the pathogen infects the host at a minimum
temperature of 22-25°c.
• Relative humidity : An RH of above 80% is ideal. Heavy prolonged dew
deposition is important for dieback development.
26. • Integrated of following practices manage the diseases effictely economically and
in a most environment friendly manner.
CULTURAL PRACTICES:
• Field sanitation:
1. Collect and burn the infected plant debries of chilli
2. Destroy self-grown solanaceous plant, other volunteer plants from the field and
surrounding areas.
27. • Seeds obtained from a diseases free crop.
• Treat the seeds with 2g of Thiram per kg of seeds before sowing for anthracnose
of chillies.
Thinning and weeding:
• Weeds serve carriers of plant pathogens and high plant density favour
development .
• Remove the weeds once before and then after the irrigation.
• Rouge out the mixture and stay diseased plant as their serve as foci of
infection.
28. IRRIGATION
• Provide only need based light irrigations, high humidity, and frequent irrigation
favour disease development.
VARIETAL:
• Resistant/ tolerant genotypes against major disease G-4 ,Pusa Jwala ,PantC-1 ,JCA
196.
29. Chemical method:
• For the management of Anthracnose chilli –
• spray of Captafol @ 0.2% followed by copper oxy chloride @ 0.25% and
Caebendizim @0.1% , two sprays at 10-15 days interval ,35-45 days after
transplanting .
30. Bacterial spots
• Major disease of chillis in tropical and subtropical climates. This appears on
leaves and fruits.
• In Rajasthan the disease cause 8-16% loss in yield of fruits.
SYMPTOM:
• On leaves ,the first indication of the disease is appear of small , circular to
irregular, water soaked area which appear as definite spots on the lower surface of
the leaf.
• As the colour changes from dark green to purplish grey with a black centre.
• A narrow yellow halo may surround the spot.
31. • In the wet weather , the leaves are too many ,the intervening tissues become dry
and brown and the whole leaf dies.
33. Etiology
• Diseases caused by Xanthomonas campestris pv. Vesicatoria.
• The bacterial cells are single ,straight rods 0.2-0.8*0.6-2.0 µm in size.
• They are gram negative and motile by a single polar flagellum.
• These bacterial are strict aerobes and optimum temperature for growth is 25-27°C.
34. Disease cycle
• It is a seed borne bacteria .10-15% seeds carry the bacteria which is enough to
initiate the disease through seedlings.
• The bacterium also subsists on infected plant debries, weeds and volunteer plants.
• Spattering rains are the chief means of local dissemination of bacterial cells from
the ooze developed on the affected parts.
• The bacteria are also rapidly spread throughout the chilli.
• movement of equipments and workers having come in contact with the diseased
plants.
35. • Field sanitation
• Use diseases free seedlings and seeds.
• Use of resistant varieties.
• Avoid sprinkler irrigation.
• Seed treatment with Agronson GN @2.5g/kg of seeds and Cersan @2.5g/kg of
seeds were used for bacterial leaf spot of chilli .
• Application of streptomycin sulphate 500ppm+COC 0.3%
36. Leaf Curl of Chilli:
• The leaf curl is very common wherever the crop is grown.it is a major initiation in
successful cultivation of both hot and bell pepper.
SYMPTOM:
The most characteristics symptom are
• the curling of leaves , small size , shortened internodes and general dwarfing of
the plant which assumes a bushy appearance.
• Leaves are pale color and roll downwards . Fruiting is stopped, if fruit are formed
, they are small and deformed.
37. • Causal agent: Tobacco leaf curl virus
• The genome consists of a single circular ssDNA.
• Whereas the genome of the other known whitefly transmitted Gemini virus
consists of two ssDNA.
• Gemini particles are paired and polyhedral .The member of this group are found
predominantly in tropical area.
40. Transmission:
•The disease is transmitted by whitefly , Bemisia tobasci.
• This vector spread the maximum diseases during the month of august to October.
• The vector acquires the virus after feeding on an infected plant for at least 15-30
minutes.
•There latent period of several hours after which the virus can be inoculated into a
healthy plant.
41. Management
Cultural control
• Nursery beds should be covered with nylon net or straw to protect the seedlings
from viral infection.
• Raise 2 -3 rows of maize or sorghum as a border crop to restrict the spread of
vector.
• Rogue out the infected plants as soon as they are noticed in the field.
42. Bio-control agents
• Different botonicals , animal products and other materials such as ash ,cow urine
,and dung ,fish meal,and milk etc.
• Rhizobacteria(PGPR),leaf proteins,proline,and Trichoderma spp.reduce diseases
in many plant species manipulating host plant’s physical and biochemical
properties.
43. • Use of milk in plant diseases management – it is the indigenous ancient tool
against plant diseases.
• Amino acids ie, proline, isoleucine and phenyl alanine in milk induce resistance
against plant diseases.
• potassium phosphate content strengthens host immune system against diseases.
Chemical method:
• Protect the crop in nursery bed from insect vectors(whitefly)by spraying
Metasystox 1ml/lt of water at 10days interval.
44. OTHER MINOR DISEASES
• BACTERIAL SOFT ROT
Erwinia carotovora pv. carotovora
Symptom:
• The internal tissue softens before eventually turning into a watery mass with a foul
smell.
• This problem is worst in wet weather beacouse the bacteria are rain splashed from
the ground and on to the fruit.
• Also started by insect injury.
45. Management :
• Keep plants off the ground
• Controlling insects can help reduce the threat
46. • BACTERIAL WILT:
Pseudomonas solanacearum
Symptom:
• Start with wilting of the leaves.
• After a few days a permanent wilt of the entire plant results,with no leaf
yellowing.
• Cutting roots or stems show milky streams of bacteria when they suspended in
water.
Management
Plant clean and transplants and to remove diseased plants.
47. • CERCOSPORA LEAF SPOT
Crecospora capsici
Symptom:
• Worst under extended warm, wet conditions.
• Characterized by small brown circular leaf lesions that have a watery appearance.
• Excessive leaf drop may occur in common infestations.
48. Management:
• Use clean seed and crop rotation
• Good air flow round plantsin sheltered areas will also help minimize
this problem.
• Fungicides like Hexaconazole 0.1% etc.
49. • PHYTOPTHORA BLIGHT
PHYTOPTHORA CAPSICI
SYMPTOM:
• Plants suffering from this condition often wilt and die, leaving brown stalks and
leaves ,small
• Poor quality fruits
• If the fungus enters the roots .
• Symptoms of the less serve leaf blight include brown or black spots that may kill a
localized portion of the plant.
• Affected areas are often borded with a white mold.
50. • Wind borne fungus ,observed in wet water logged condition.
• It is promoted by warm , wet weather
Management:
• Avoid excess watering and poorly drained soil.
• Fungicides : Mancozeb@0.2%
51. • The cultivated chilli suffers from number of fungal ,bacterial ,and viral diseases.
• Among the fungal diseases damping off and anthracnose are the major devastring
diseases causing considerable yield loss .
• Environment play an effective role for development of these diseases.
• Diseases perpetuate through plant debries in soil ,special fruiting body ,volunteer
host and weeds year to year .
• The diseases can be managed effectively and eco friendly by cultural practices and
applying economic chemicals.
