Seed Health Management for Better Productivity - Govind Ballabh ...

(Seed Health Management for Better Productivity)loose smut. The smut spores being formed in place of grains get blown away by wind as the thinmembrane ruptures leaving behind the bare rachis in loose smut, while the inflorescence tend toretain its shape in case of covered smut infection due to presence of persistent membrane(epidermis) covering the smut spores. Loose smut and covered smut being internally andexternally seed borne respectively can be best managed by seed treatment with differentchemicals as used for loose smut of wheat.Rice Leaf Smut (Entyloma oryzae)The disease initially reported from India and Burma is now known to occur in Japan,Taiwan; Philippines, Afghanistan Venezuela, USA and China. However, the disease is noteconomically much important. The disease is characterized by distinct lead black colored sporeslinear, rectangular or angular in shape, and covered by epidermis which ruptures only when theleaves are soaked in water. As disease perpetuates through hypophyllous sori lying in the field indiseased leaf trash, it can be controlled by following clean cultivation practices.Paddy Bunt (Neovossia horrida or Tilletia barclayana)Paddy bunt initially being reported from Japan has now spread to almost all rice growingareas in India and abroad in Uttar Pradesh, the loss has been estimated up to 3.2 per cent. Thedisease has become a major bottleneck in hybrid seed production. Because of localized air borneinfection all ears in a stool and all grains in a ear are not affected. Usually the sori are hidden byglumes but sometimes glumes are forced apart giving a appearance of minute black pustules orstreaks as a feature of disease. As the disease is initiated by air borne sporidia produced fromtetiospores lying in the soil at the time of flowering, seed treatment is not so effective, howeverfoliar sprays of the same chemicals as used for karnal bunt of wheat are recommended atflowering stage. Cultural practices like crop rotation, field sanitation etc. help in reducing inoculum.Usually early sowing varieties escape infection of florets by air borne sporidia The tolerance levelsfor kernel smut of rice are fixed at 0.1 and 0.5 % for foundation and certified seed, respectively..Smut of Sugarcane (U. scitaminea)The disease has been reported from all sugarcane growing areas of the world except Australia.In India, it is more serious in tropical regions (Maharashtra, Andhra Pradesh, Karnataka, and Kerala)causing both cane yield and quality losses. The disease is characterized by the formation of whip likestructure having black smut spores arising from the central axis of plant. The affected canes becomeslender and thin. As the disease perpetuates through smut spores present on infected canes/canesets or ratooned canes, the disease can be managed by following cultural practices like removal ofsmutted whips, avoiding preparation of plant sets from smutted canes, discouraging the practice ofratooning, along with disinfection of sets before planting with Agallol (0.25% suspension), mercuric- 124 -