Tikka disease of groundnut is a disease which also refers to “Leaf spot disease”. The causal organism of tikka disease are the species of the genus Cercospora namely Cercospora arachidicola and Cercospora personata. Tikka disease cause epidemics in all groundnut crop growing countries including United States, China, India etc. according to the survey, it can decrease the crop yield by approximately 22%.
Cercospora arachidicola cause ” Early leaf spot” which characterizes by the appearance of brown spots with a yellow halo are few in number and small in size. Cercospora personata cause “Late leaf spot” which characterizes by the appearance of black spots that are common, more in number and potentially more damaging.
Groundnut: Its biological name is Arachis hypogaea. Groundnut is rich in protein, dietary fibres, fat and other nutrients. According to the studies, groundnut is found to reduce cardiovascular disease.
Groundnut is used commercially in many areas like manufacturing of edible oil, in textile industries by the use of its fibres (Ardils), cosmetic industries etc. Therefore tikka disease of groundnut can cause huge damage to such an economy by reducing the yield or causing damage to the groundnut.
Content: Tikka Disease of Groundnut
- Causal Organism
- Difference Between Early and Late leaf spot Disease of Groundnut
- Favourable Factors
- Disease Cycle
- Control Measures
Causal Organism of Tikka Disease
The causative agent of tikka disease of groundnut belongs to the genus Cercospora by two different species namely Cercospora arachidicola and Cercospora personata.
- Kingdom: Fungi
- Phylum: Ascomycota
- Class: Dothideomycetidae
- Order: Capnodiales
- Genus: Cercospora
Distribution: Widespread in tropical countries where the groundnut crop production is more.
Difference Between the Features of the Causal Organism
Cercospora arachidicola and Cercospora personata show different features which include:
- Cercospora arachidicola are dark brown in colour and grows intracellularly in the plant cell.
- Cercospora personata are brown-black in colour and first grows intercellularly and later intracellularly.
- Cercospora arachidicola lack haustoria.
- Cercospora personata contains branched haustoria.
- Cercospora arachidicola consists of continuous, unbranched, yellowish-brown, geniculated and septate (1-2 septa present). It is 22-44 µ long and 3-5 µ wide.
- Cercospora personata consists of continuous, unbranched, light brown in colour, geniculated and aseptate. It is 25-54 µ long and 5-8 µ wide.
- Cercospora arachidicola consists of long, cylindrical, hyaline (Pale yellow in colour) conidia. It is 38-108 µ and 6-8 µ wide. The shape of conidia truncates at the base and sub truncates at the apex. Conidia of Cercospora arachidicola is septate around 1-12 septa are present.
- Cercospora personata consists of short, cylindrical conidia. It is 18-60 µ and 6-11 µ wide. The shape of conidia is rounded at one end and tapered on the other end. Conidia of Cercospora personata is septate around 3-4 septa are present.
- Cercospora arachidicola grows intracellularly.
- Cercospora personata first grows intercellularly and later grows intracellularly.
Similarities Between the Causal Organism
- Both Cercospora arachidicola and Cercospora personata are pathogenic.
- The mode of nutrition is saprophytic and parasitic of both Cercospora arachidicola and Cercospora personata.
Symptoms of Tikka Disease of Groundnut
- Cercospora arachidicola cause early leaf spot infection which includes symptoms like brown coloured round or oval spots in an irregular fashion and surrounds by the yellow halo.
- Cercospora personata cause late leaf spot infection which includes symptoms like dark black spots which are comparatively bigger than the size of early leaf spot.
Difference Between Early and Late leaf spot Disease of Groundnut
|Properties||Early leaf spot of groundnut||Late leaf spot of groundnut|
|Occurrence||It occurs early||It occurs late|
|Infection||It cause early or primary infections||It cause late or secondary infections|
|Effect||Effects the upper leaf||Effects the upper leaf|
|Spots arrangement||Arranged randomly||Arranged in concentric rings|
|Shape of spot||Circular to irregular||Circular|
|Size of spot||Smaller||Comparatively larger|
|Colour of leaf spot||Light brown to black spots with yellow halo||Dark brown to black spots|
There are certain environmental and chemical factors that favour the disease incidence of tikka disease which includes:
- Prolonged low temperature
- Heavy dew
- Usage of nitrogen and phosphate fertilizers.
Disease Cycle of Tikka Disease
The disease cycle of tikka disease of groundnut is carried out by the fungal spores of the Cercospora species i.e. Cercospora arachidicola and Cercospora personata.
In the disease cycle first, the conidia remain in a dormant state in the crop residues of the infected plant. Then, the spores i.e. conidia of Cercospora sp. Disseminates by the factors like wind, rain, insect vectors to the host plant surface.
After that, the conidia germinate on the favourable conditions and results into a germ tube formation, by entering into the plant cell through the stomatal pores. There it causes primary infection on the host surface and the symptoms appear within 30days after planting.
Then the spores multiply and form a high number of hyphae or a mycelial network. These hyphae then rupture the epidermis wall of the plant cell and emerge out in the form of long conidiophores.
These conidiophores then develop spores i.e. conidia on the favourable conditions. After that, the conidia detaches from the conidiophore by unwanted factors like wind, rain splashing etc.
Then after detachment, the conidia will either remain at a dormant state in the soil or it can infect the other host plant. Therefore, the disease cycle continues like this way only.
Management of early tikka disease/ leaf spot disease of groundnut:
The early infections of tikka disease can be managed by the following ways, which includes:
- Crop rotation
- Eradication of infected plants by burning or burying them in deep pits.
- Pruning can also be done with the help of pruning scissors by removing the infected parts of the plant.
- The seeds of groundnut that are within the shells can be disinfected with sulphuric acid and those which are without the shell can be treated for half an hour with 0.5% of copper sulphate solution.
- Raw seeds after dressing with Agrosan GN can also reduce the chances of infection.
Management of late tikka disease/ leaf spot disease of groundnut:
The late infections of tikka disease can be only managed by the use of effective fungicides like Bordeaux mixture as a spray etc.