3. Introduction
Groundnut is the most important oilseed crop of india
The total area under ground nut is about 8 million hectares
Tikka disease is the major disease of groundnut In india
It occurs in every state in India and in every ground of nutgrowing countries of the
world
In Uttar Pradesh , the disease locally known as chitwa or haldai
4. Causal organism
The causal organism of this disease are Cercospora personata and Cercospora
arachidicola
The symptom caused by the two pathogen will differ
This disease also called Leaf spot of Ground nut because it causes Leaf spot on the
leaves
5. Symptoms
Symptoms appear when the plants are 1 or 2 months old
Due to excessively spotting on the leaves , there is gradual weakening of the
foliage which results in defoliation
Consequently , fewer and smaller nurs are formed
According to sundarram (1965) severe intensity of infection leads upto 22%
reduction in yield
6. Symptoms
C.arachidicola causes early spot and C.personata causes late spot
First symptom of both leaf spots is the appearance of pale areas on the upper
surface of older leaves
As the lesion develops the two species can ve distinguished
7. Early leaf spot symptoms
Sub circular dark brown spots are produced on the upper leaflet surface
Spots are of lighter shade of brown on the lower side of leaflets
Yellow halo is seen around the brown spots
8. Late leaf spot symptoms
Late leaf spots are nearly circular and darker than early leaf spots
Yellow halo develops around each only in later stage of development
Late leaf spots can be distinguished from those of early leaf spots
Late Leaf spots are darker with no or light yellow halo
9. Causal organism
The mycelium of C.arachidicola is inter and intracellular,brown, septate and without
haustoria.
Conidiophores are yellow brown and as the conidium remains attached to
geniculation oj conidiophore.
Conidiophore are 22-44 micron long and 3-5 microm broaf continuous or 1-2
septate.
10. Causal organism
Cercospora personata produces an intercellular branched mycelium
To absorb food from the host tissue, haustoria are developed.
Lesions appear 2-4 weeks later.
Conidiophore of C.personata are 25-54 micron long,5-8 mircon Broad continuous
or 1-2 septate.
Conidia are terminal and each conidiophore bear each single conidium at the apex.
It is potentially more damaging because it produces more spots, spreads faster and
causes earlier defoliation.
11. Dieseade cycle
Perennation
The disease perpertuates through conidia lying in the soul on diseased plant debris
and through conidia being carried in thr shell of groundnut.
Primary Infection
When the new crop of Groundnut starts growing,the viable conidia are brought to
the host surface by various agencies, germinate in favourable conditions and cause
primary Infection.
Secondary infection
The secondary infection on healthy plants in the same field or adjacent fields is
brought by conidia produced on primary infected leaves.
12. Cont.....
The conidia are dispersed by air or other agencies , which bring them on the
healthy leaves
Later , they germinate in favourable conditions and causes infection
13. Favourable factors
Relative humidity is the most important factor for infection
A period of three days of high humidity is essential for maximum infection
Prolonged low temperature and dew also favour Severe infection
14. Unfavorable condition
Application of potash slightly decrease disease incidence
Leaf spot development is minimal when gypsum is applied as a source of calcium
15. Disease management
As the disease is soil borne, proper crop rotation is needed
Plant disease debris should be burnt to avoid soil infection
Early planting, alteration in date of sowing and use of maturing varieties helps to
escape room the attack of disease
Foliage spray with Bordeaux mixture , Dithane M-45(.2%), Benlate and Bavistin (0.1)
give good result
16. Conclusion
Tikka disease is the common disease in ground nut caused by Cercospora
arachidicola and Cercospora personata
In the diseased condition , many circular spots appear on the surface of leaf
Conidia of the fungus present in soil or those present in the fruit shell is the source
of infection
Use of fungicides controls the disease
