1. DISEASE OF FIELD AND
HORTICULTURAL CROP AND
THERMANAGEMENT - II
Disease of Gram
By – Shaily
Riyanshi Bhatt
Nitesh Verma
2. 1. Ascochyta Blight
Introduction
Caused by Ascochyta rabiei
Ascochyta rabiei, also known as Didymella rabiei, is a fungal
pathogen that causes Ascochyta blight (AB) in chickpeas. AB is
a widespread disease that can severely affect chickpea yields,
especially in cool, humid weather.
3. Favourable conditions -
■ High rainfall during flowering
■ Periods of morning dew
■ Areas where rainfall and/or high humidity occur during the growing season
■ When the crop canopy closes, the dense growth prevents dry air from entering
the canopy
4. SYMPTOMS:-
All plant parts are affected.
Symptoms appear on leaves as water soaked lesions.
Symptoms include smaller circular brown spots on leaves.
Under favourable conditions, these spots enlarge rapidly and coalesce, blighting the leaves
and buds.
In case of severe infection, the entire plant dries up suddenly.
The lesions are also developed on stems and petioles.
Late infections result in shrivelled and infected seed
The disease is seed borne in nature. Left over debris in the fields serve as a source.
Wet and warm weather, and dense crop canopy are conducive to the spread of the disease
6. DISEASE CYCLE
■ The blight causing pathogen is seed borne in nature and can overwinter in the
field on stubble for several year. In spring, sexual spores (ascospore) are
produced in field stubble or seed and dispersed by wind. Ascospore dispersal
can continue for several weeks and usually occur before or at flowering. The
spore can travel up to five miles which allows disease spread to new areas
rapidly.
8. MANAGEMENT
• Sow disease-free seed.
• Follow rotation crop.
• Hot water seed treatment (52 C for 10 min) to lower the infestation. • Use of
resistant/tolerant cultivars
• Destruction of host weeds and plant debris.
• Seed treatment with Thiram, thiobendazole, hexacap, captaf @ 3 g/Kg seed. •
Application of 2-3 sprays of Dithane M
9. 2. Grey Mold
INTRODUCTION :-
Gray mold, or Botrytis blight, is a disease caused by the
fungus Botrytis cinerea. It’s a widely distributed disease
that can infect vegetables, soft fruits, flowers, trees, and
shrubs. It’s especially likely to occur when conditions are cool
and damp.
10. Favourable conditions -
Fungus sporulation and infection, is favoured by cool and wet weather
Temperatures of 17–23°C, RH – 90%
Excessive application of nitrogen makes plants such as young transplants more
susceptible to gray mold
High canopy density creates conditions for extended leaf wetness at night and
subsequent increased gray mold severity
11. SYMPTOMS -
Brownish spots develop near the soil line or cotyledons.
Water-soaked lesions on leaves & stems darken and collapse.
Water-soaked spots that rapidly expand into large yellowish-green or grayish-brown,
irregular lesions that are soft and spongy in texture.
Identification of pathogen
Botrytis cinerea – abundant hyaline conidia (asexual spores) borne on grey, branching
tree-like conidiophores
It overwinters as sclerotia or intact mycelia, both of which germinate in spring to produce
conidiophores
The conidia are dispersed by wind and rain-water and cause new infections
Favourable conditions and spread:
14. MANAGEMENT -
Field sanitation – remove and burn decaying infected plant parts
Space seedlings and transplants to allow for free flow of air through
the crop
Treatment with hot air at 38°C for 48-72 h or hot water at 50°C to
53°C for 2 to 3 min
15. 3. Wilt
■ INTRODUCTION
Caused by:- Fusarium oxysporum spp.
Wilt is a disease that causes leaves to wilt by disrupting the
flow of water in the xylem. It can be caused by pathogens,
such as fungi, bacteria, nematodes, or other micro-
organisms.
16. SYMPTOMS -
• Leaves initially pale
Leaves lose their turgidity
Leaves droop down
Large scale withering
Gradual or sudden wilting from bottom to top
Stunted growth
Tylose formation in the vascular tissues
Blocking in transport of nutrients and water
19. MANAGEMENT -
➤ Follow crop rotation measures continuously.
➤Always use disease free seeds.
➤Avoid sowing when temperatures are high.
➤Follow 6-year crop rotations with sorghum
Apply FYM 10-15 cart load/ha.
➤Seed treatment with T. Viride @4g/kg or P.
Fluorescens @10g/ kg of seed or Carbendazim or
