1. T.C.B College of Agriculture
And
Research Station.BILASPUR
chattisgarh
Presented To; Presented By;
Dr. R.K.S. Tiwari SHEKH ALISHA
Dept. of Plant pathology B.Sc. Ag 2nd yr 2nd sem..
SYMPTOMS OF DISEASE
SESSION -2015-16
2.
3. • C. malayensis causes brown, irregular spots and C. abelmoschi
causes sooty black,
• angular spots on lower surface of leaves
• Both the leaf spots cause severe defoliation and are common during
humid season
CAUSAL ORGANISM: Cercospora abelmoschi
• Symptoms mainly appear as on minute spots mainly on the lower
surface of the leaves which later on increases in size and appear as
rectangular in shape and is confined to intervenial area.
• Affected leaves roll wilt and fall down.
• Symptoms starts on petiole as olivaceous spot or lesions as a
result the petiole detaches from twigs or branches and
defoliation occurs.
4.
5. CAUSAL ORGANISM: Leptosphaeria coniothyrium
• Spots start as small yellow or reddish
discolouration around wound that turns
with a dark brown border.
• Drying of twigs starts with development of
elongated lesions of brownish color
followed by drying of affected tissue.
6.
7. CAUSAL ORGANISM: Abiotic & Biotic causes
1.Bunchy top 2.Vegetative malformation
3.Floral malformation
• Bunchy top: Excessive formation of leaves on the
affected part of plant
• Vegetative malformation: Excessive formation of scaly
leaves on affected plants and directly attached to the
branches arising from auxillary buds and nodes.
• Floral malformation: Whole infloresence is converted
into thick leafy stucture and becomes sterile in nature.
8.
9. CAUSAL ORGANISM: Phytopthora infestans (mont) de Bary
• Initially starts from leaf tips or margins and spread inward
• Small water soaked or faded green patches on upper surface of
leaf which turn brown
• Spots enlarge and zonations as concentric rings develop in them
• Downy growth of the pathogen correspondingly on lower
surface
• Progressive defoliation and collapse of plants under favourable
conditions
• Water soaked stripes on stem which becomes necrotic
• Purplish brown spots appear on skin of tubers
• On cutting, the affected tubers show rusty brown necrosis from
surface to the centre
• Decay of plant parts under favourable weather which emits foul
smell