BLAST OF FINGER MILLET

DISEASE OF FIELD CROPS

1. 111718012016 G . Pujitha Reddy RAGI / FINGER MILLET ( Eleusine coracana )

2. Blast Pyricularia grisea Economic importance : It is the most important disease on ragi . It causes heavy damage to the crop under favourable environmental conditions. In Chittoor district of A.P, it is more or less endemic. Yield loss may range from 50% to 90%.

3. Symptoms : Infection may occur at all stages of plant growth. Young seedlings may be blasted or blighted in the nursery bed as well as developing young plants in the main field. There are three stages in disease development.

4. Leaf blast Node blast Neck blast

5. Leaf blast : It is more severe in tillering phase. The disease is characterized by spindle shaped spots on the leaves with gray centers surrounded by reddish brown margins.

6. Node blast : Infection on stem causes blackening of the nodal region and the nodes break at the point of infection. All the parts above the infected node die.

7. Neck blast: At flowering stage, the neck just below the earhead is affected and turns sooty black in colour and usually breaks at this point. In early neck infections, the entire earhead becomes chaffy and there is no rain set at all. If grain setting occurs they are shrivelled and reduce in size.

8. Pathogen : Young hyphae are hyaline and septate and turns to brown when become old. Numerous conidiophores and conidia are formed in the middle portion of the lesions. Conidiophorse are slender, thin walled, emerging singly or in groups, unbranched , and pale brown in colour . Conidia are thin walled, sub- pyriform , hyaline 1-2 septate , mostly three celled with a prominent hilum .

9. Pathogen of pyricularia grisea

10. Disease cycle : The fungus is seed-borne and the primary infection takes place through the seed-borne conidia and also through diseased plants, stubbles and weeds. The secondary spread is through air-borne conidia.

11. Disease cycle of pyricularia grisea

12. Favourable conditions : Application of high doses of nitrogenous fertilizers. Low night (20 degree celsius ) and day (30 degree celsius ). Temperatures with high relative humidity (92%-95%) and rain or continuous drizzles favour the diease development. Presence of collateral hosts like bajara , wheat, barley and oats.

13. Management : Destruction of collateral hosts and infected plant debris. Treat the seeds with captan or thiram @3g/kg or carbendazim at 2g/kg. Grow resistant varieties like ratnagiri , padmavati , gowtami and godavari . Spray with carbendazim @ 0.2% or iprobenphos (IBP) @0.1% or edifenphos @0.1%, first spray immediately after symptoms apperance and second spray at flowering stage.

14. Smut Melanopsichium eleusinis Economic importance: The disease of minor importance being found only in certain places of Karnataka and Maharashtra. Symptoms : Disease appears mostly during kharif at grain setting stage. Only few scattered grains in a head are attacked and transformed into globose galls of 5-15mm diameter, greenish at first and turning black at maturity. The sorus ruptures releasing black mass of spores.

15. Pathogen : The fungus is mostly confined to the spikelets . Being present in the form hyphae with thickend cells or chlamydospores . The spores are globose with a rough , spiny or pitted spore wall. They measure 7-11 diameter and readily germinate in water producing sporidia on seperate promycelium .

16. Smut of ragi

17. Disease cycle : The disease is mainly air borne, infecting only few spikelets in the panicle or they may reach the soil subsequent to harvest. During the following season the spores germinate to produce masses of sporidia which become air borne and infect spikelets

18. Management : Crop rotation Rouging and destruction of affected earheads reduces smut incidence. Grow resistant varities .

19. Thank you