a brief description on diseases of pea their symptom and casual organism. Content is for eduacational purpose and truly for students ,scientist and farmers. students presentation

1. A powerpoint presentation
by-
Punam Lakra
Vandana Medihare

2. TOPIC-
“DISEASES ON PEA”

3. CONTENTS
S.NO. PARTICULARS
1. LIST OF DISEASES
IN PEA
2. NOTE ON DISEASES
3. IDM STRATEGIES ON
DISEASES OF PEA

4. LIST OF DISEASES
S.NO. DISESASES CAUSAL ORGANISM
1. Ascochyta blight/Black
Spot
Ascochyta pinnodes,Ascochyta
pinodella and Ascochyta pisi
2. Fusarium Wilt Fusarium oxysporum fsp. pisi
3. Downey Mildew Peronospora pisi
4. Powdery Mildew Erysiphe polygoni
5. Bacterial Blight Pseudomonas pisi
6. Early Browning of pea Pea Early Browning Virus
7. Pea Enation Mosaic Pea Enation Mosaic Virus

5. PEA DISEASES
Peas are subject to a number diseases,several of which
may cause serious injury or loss.Annual losses from
diseases vary from year to year,depending often on
local weather conditions.
If the soil is wet from excessive rains and the weather is
cool,heavy losses may be expected from root rots and
from such diseases as Ascochyta and bacterial blights.
If the soil is badly infested with root rotting organisms,
total loss may result.

6. ASCOCHYTA BLIGHT
Introduction
 Ascochyta blight is caused by 3 pathogens(Ascochyta
pinnodes,Ascochyta pinodella and Ascochyta pisi) those occur as
a complex in the field.
 The ascochyta blight disease complex affects field peas
(Pisum sativum), as well as many other legumes such as
chick peas, lentils, and faba beans.

7. SYMPTOMS:
 Ascochyta blight is characterized in part by the
formation of black to purplish streaks on the stem.
 The lesions are more conspicuous at the nodes and
enlarge into brown or purplish irregularly shaped
areas scattered indiscriminately from the roots to 10
inches or more up the stem.
 The spots may be very small, purplish, and very
irregular in shape and size, or they may be fairly
large and more or less circular.

8.  Under favorable conditions, the entire leaf of a very
susceptible variety may be so badly injured that it
shrivels and dries up.
 The symptoms on the pods are similar to those on
the leaves, except that the spots on the pods are
sunken and have no concentric circles.

9. Disease Cycle
 The fungi that cause ascochyta blight may either be
seed borne, soil borne or survive in pea trash.
 The disease usually becomes established when
sexual ascospores of the fungus (A. pinodella),
produced in perithecia on old pea stubble, are
carried into the new crop by rain and wind causing
early infection.
 Asexual conidia are produced by other pathogens in
pycnidia (fruiting bodies) and can infect pea plants at
any stage of plant growth.

10.  Ascospores are the main source of primary infection,
whereas the secondary infection is caused by production of
conidia.
 Discharge of both types of spores needs rainfall or dew
therefore epidemics are more severe in wetter
conditions. Spores produced on infected foliage are
transferred onto adjacent healthy plants by wind and rain
splash.

11. Management
 Use Clean Seed
 Destroy Old Pea Crop Residues
 Rotate crops so there is at least 3 years between Pea
crops and often 4 or 5 years may be required.
 Follow the recommended sowing rates and sowing
dates for your district. Avoid early sowing at high
seeding rates.
 Don’t mix fungicide with inoculants as this will reduce
the number of rhizobia.
 Apply all foliar fungicide sprays before rain.

12. FUSARIUM WILT
Introduction
 Fusarium wilt of peas is caused by a fungus(Fusarium
oxysporum fsp. pisi) that is very similar to organisms
causing wilt in a number of other cultivated plants,
including tomato, sweet potato, cotton, cowpea, water-
melon, and cabbage.
 Wilt-affected plants are more difficult to pull from the soil
than those damaged or killed by root rots

13. SYMPTOMS:
 Plants may become infected at any stage of growth.The
first symptoms are usually a yellowing of the lower leaves
and a stunting or dwarfing of plant growth.
 The stipules and margins of the leaflets curl downward and
inward.
 The stems at or near the soil line may be slightly thickened
and brittle.
 The lower stem shows black discoloration of the water-
conducting tissue (xylem) within the stem.
 Affected plants may wilt and die either slowly or rapidly
soon after the first symptoms are noted due to destruction
of the feeder roots.

14. Disease cycle
 Fusarium oxysporum is a common soil pathogen
and saprophyte that feeds on dead and decaying
organic matter.
 It survives in the soil debris as a mycelium and all
spore types, but is most commonly recovered from
the soil as chlamydospores.
 This pathogen spreads in two basic ways: it spreads
short distances by water splash, and by planting
equipment, and long distances by infected
transplants and seeds.
 F. oxysporum infects a healthy plant by means of
mycelia or by germinating spores penetrating the
plant’s root tips, root wounds, or lateral roots.

15. MANAGEMENT:
 Clean cultivation
 Use of certified seeds only.
 A 5-year rotation or longer, using crops other than peas,
 The prevention of movement of all pea vine debris to
other fields, will help to prevent buildup of wilt fungi in the
soil.
 Resistant variety-Norli,Lincoln

16. DOWNY MILDEW
 Downy mildew of pea is caused by Peronospora pisi
Sydow, whose mycelium consists of aseptate,
branched,hyaline hyphae, confined to the intercellular
spaces of the host tissues.

17.  Symptoms of Downy Mildew of Pea:
1) Yellow to brown scattered patches of discoloured areas
appear on the upper surface of the leaflets and stipules.
Simultaneously with this, downy growth in patches of
variable size are visible on the under surface
corresponding with the lesions of the upper surface. The
downy coating is whitish when young, but the colour
gradually turns greyish-violet with age.
2) When young,the blotches on the pods are pale-green,
more or less elliptical to irregular, but gradually the
blotches turn dark to bright-brown, mottled with light-
green islands.
3) Blotch followed by the green island effect is a typical
symptom of the disease.

18.  Disease Cycle-
Cool humid condition is very favourable for the
development of the disease, while the disease incidence is
slowed down with warm condition.This is due to the fact
that the sporangia which behave as conidia spread the
disease, but cannot stand desiccation.
 The sporangia are blown about freely by the wind and
spread the disease rapidly from plant to plant.

19.  Management-
1) Since the causal organism survives from season to
season in the form of oospores in the plant debris, the
destruction of previous year’s plant debris and following
crop rotation of two or three years are very effective
control measures.
2) Spraying and dusting pea plants with fungicides are
effective in limiting the spread of the disease.
3) Deep tillage to bury crop residues.
4) Use tolerant cultivars.
5) Use metalaxyl for seed treatment.

20. POWDERY MILDEW
 The powdery mildew of peas is worldwide in occurrence
causing serious losses to the crop. The disease is
considered to be much more serious than the downy
mildew of peas.
 In India, the disease generally appears during November-
December.

21.  Symptoms of Powdery Mildew Disease:
1) First symptoms appear on the leaves in the form of white
floury patches on both sides of leaves. The disease then
spreads to other green parts of the plant such as tendrils,
pods, stems etc. The patches on the leaves originate in
the form of minute discoloured specks from which
powdery mass radiates on all sides.
2) In the advanced stages of the disease large areas of the
host get coveted with white floury patches. Infected
plants impart dirty appearance.
3) In extreme severe infections the infected leaves are shed
leaving stem devoid of the leaves.

22. DISEASE CYCLE OF POWDERY MILDEW
 Primary source of infection-Infected debris
 Secondary source of infection-wind blown conidia
 Fungus survives in summer leftover debris.
 Seed is not considered as main source of inoculum.

23. •Management-
 Avoid late planting.
 After harvest, collect the plants left in the field and
burn them.
 By formulation of wettable Sulphur such as Sulfex
and Thiovit at 3 kg/ha.
 0.03 % Calixin followed by Karathane (0.2%) and
Bavistin (100 ppm)
 Grow resistant varieties like JP-83, PM-2, JP-4, and
JRS-14.

24. BACTERIAL BLIGHT
Introduction
 This disease, caused by the bacteria Pseudomonas
syringae pv. pisi , is a serious disease of peas.

25. Symptoms
 This disease affects all above-ground plant parts.
Seedlings from infected seed may die. The affected
leaflets have small, round, oval or irregular spots of
reddish brown colour with translucent centre with a
darker brown margin.
 Several spots merge to produce blight appearance.
 Chocolate brown linear streaks on stems and petioles.
 Pods are chocolate brown, thin, twisted and shriveled.
 Pod surface are glossy due to dried bacterial ooze.
 Seeds become discoloured and shriveled.

26.  Disease Cycle
 Bacterial blight commonly becomes established within a
field by sowing infected seed or from infected pea trash
that is nearby.
 During wet weather, bacteria spread from infected to
healthy plants by rain splash and in wind-borne water
droplets.
 The pathogens can remain on the surface of plants
without causing symptoms. However, following rain,
heavy dew, frost or other forms of damage to plant
tissues, symptoms can develop.

27. MANAGEMENT:
 Always sow healthy seeds procured from disease-free
crop or certified seeds.
 Invariably discard discoloured and shrivelled seeds and
give a pre-sowing seed dip in Streptocycline solution
(1g/10 liters of water) for 1-2 hours.
 Give a spray of Streptomycin (0.01%) on appearance of
first symptoms of the disease and repeat after 7 days, if
necessary.
 Follow a 3 years crop rotation.
 Practice sanitation, keep proper drainage and give
appropriate spacing between plants.

28. PEA EARLY BROWNING
 Pea early browning virus (PEBV) is a plant pathogenic
virus.
 Pea early browning virus (PEBV) is a member of the genus,
Tobravirus. It is transmitted by soil-inhabiting trichodorid
nematode(Paratrichodorus anemones) and through seeds
from diseased plants.

29.  List of symptoms/signs
1) Leaves - abnormal colours
2) Leaves - abnormal patterns
3) Leaves - necrotic areas
4) Seeds - discolorations
5) Whole plant - dwarfing
6) Whole plant - early senescence
7) Advanced symptoms in the crop show as brown patches
of poor growth, particularly when infection with PEBV
occurs early in the season (Bos and van der Want, 1962)

30.  Management-
1. Removal of infected seeds.
2. Use healthy disease free certified seeds.
3. Avoid cultivation in land with vector infested soil.

31. PEA ENATION MOSAIC VIRUS
 Pea enation mosaic virus (PEMV) is a plant pathogenic virus.
 The two RNAs of the disease are now categorised as two
separate, mutualistic viruses: PEMV-1 is an Enamovirus,
while PEMV-2 is anUmbravirus.
 It is spread by pea aphid (Acyrthosiphon pisum) and to a
lesser extent by the green peach aphid (Myzus persicae).
 Also affects legumes as pea, alfalfa, broadbean or sweet
pea mostly in temperate regions.
 There are 8 total species known to transmit PEMV.

32.  Symptoms-
 It includes chlorotic, translucent or necrotic lesions,
malformation of leaves and stipules, and plant
distortion.The most characteristic symptom is the formation
of enations on the abaxial.
 Enations are derived from the cells of vascular bundles
undergoing hyperplasia.

33.  Cultural and Physical Control measures-
1) Use of resistant(Oregon pioneer) or tolerant cultivars.
2) If using susceptible varieties, planting before March 31 helps
avoid aphid infestation.
3) Spray water to knock aphids off plants.
 Biological Control measures-
1) Green peach aphid or pea aphid predators and parasites can
be used to prevent an outbreak of PEMV.
The most common enemies of these aphids are:
1. Lady bird beetles(Coleoptera: Coccinellidae)
2. Flower flies (Diptera: Syrphidae)
3. Lacewings (Neuroptera: mainly Chrysopidae)
4. Parasitic wasps (Hymenoptera: Braconidae).
 No chemical control measures have been recommended yet.

34. IDM STRATEGIES ON DISEASES OF PEA
 IDM includes-
1. Use of moderately resistant. varieties(Avalanche,Sugar
Bon,Sugar sprint),tolerant varieties(Bolero),disease free
seed.
2. Crop rotation.
3. Delay in the sowing.
4. Disease forecast model that predicts the time of onset
and progression of ascospores maturity and spread of
spores from the source of infection.
5. Need based foliar and in-furrow applications of fungicides
in conjunction with other agronomic practices (Kraft et al.,
1998).