Blast infestation in rice has been reported from many places of Andhra Pradesh State. In Telangana, Andhra and Rayalaseema zones, the disease has been reported to an extent of 10-20 per cent during this season.
There are broadly three types of blast. The first is called as leaf blast. Infested crop leaves exhibit spindle shaped spots with brown margin and grey dots.
This type has been prevalent in Warangal, Karimnagar, Khammam, Krishna, East Godavari, West Godavari, Nellore, Srikakulum and other districts of Andhra Pradesh for the last few weeks.
The second type is node blast. Caused by a fungus, the symptoms are crop turning black in colour and panicles breaking easily.
The third type is called neck blast. This starts during panicle emergence initiation of the crop period. The neck region is blackened and shrivelled. Grain set in ears is completely or partially inhibited.
Out of the three, neck blast is more severe and results in yield losses to a great extent.
Favourable environmental factors such as prolonged dry periods, cool nights, low night temperature, high relative humidity, cloudy, drizzling weather and high nitrogen supply increase all the three disease incidences.
— Healthy disease free seeds alone should be used for sowing.
—Use disease resistant or tolerant rice cultivars
—Seed treatment with tricyclozole 75 WP at 2.0 g or carbendazim at 1.0g per kg seed as wet seed treatment or carbendazim at 3.0 g per kg as dry seed treatment.
— Seeds should not be collected from infested fields.
— Remove weeds and collateral hosts from field and bunds. Balanced fertillizer application is a must.
— At the time of harvesting, infested plants should be removed and destroyed.
—Field bunds and irrigation channels should be kept clean. Avoid excess application of nitrogenous fertilizers.
Spraying of fungicides like tricyclozole 75 WP at 0.6 g or isoprothiolane 40EC at 1.5 ml or kasugamycin 3 L at 2.5 ml will be more effective.
(Dr. A. Vijaya Bhaskar Rao is Scientist ( Plant Pathology), email:firstname.lastname@example.org, mobile: 098498 17896, Regional Agricultural Research Station ,Warangal, Acharya N.G.Ranga Agricultural University, Hyderabad, Andhra Pradesh.)