Dr.Shahid Ahmad
For the last five years yellow rust disease of wheat is assuming important disease of wheat and it is occurring in entire Jammu regions viz. Reasi, Udhampur, Jammu, Kathua, Samba Districts. In Reasi and Udhampur it has occurred from ending of January and at present it has occurred from 10-50 per cent wheat growing region. Farmers of the districts are aware of diseases management practices through Farmers Trainings, Kissan Gosthi, Campaign. Krishi Vigyan Kendra, Reasi is striving hard to aware farmeers about its difrent programmes and had distributed 1,000 of Pamphlets. Severe infections can cause yield losses, mainly by reducing the number of kernels per spike, test weights, and kernel quality.
It is caused by Puccinia striiformis f.sp. tritici. Symptoms appear as small, bright yellow pustules (uredia) closely arranged in rows are stripes, parallel to veins appear on upper surface of leaves and leaf sheaths. The yellow pustules can also develop on heads including awns. The arrangements of pustules in stripe (resembling sewing machine stitches) are a prominent visual symptoms distinguishing it from other two rusts of wheat. On maturity, the pustules break- open, releasing a yellow orange mass of uredospores. In severe conditions, the serial arrangement seems to have lost due to over-crowded pustules. As the plant approaches maturity, dull black telia (bearing teliospores) often develop on low surface of the leaves. The telia remain covered by the host epidermis as a black flat crust.
Wheat is the only known host of P.strifformis f.sp. tritici. Since, only uredospores and teliospores are known to occur, it seems to be a hemiform rust. The pathogen perpetuates through uredispores on volunteer self sown wheat at high altitudes. In India, the pathogen survives in Himalayan foothills in J and K, Punjab, HP and western UP from there, the uredospores are blown to comparatively lower altitudes and finally reach to plains in the month of February to cause primary infection. Of the three rusts of wheat it appears earliest in the Indian plains. Low night temperature and presence of due are favourable for the disease. Under such conditions, new generations of uredpspores (repeating spores) can be produced at every 8-10 days causing fast secondary spread of the disease. If crop maturity is delayed due to extended winter, it is likely that the crop may face terminal severity of the rust.
Management
The rust is best managed by use of resistant varieties. Fortunately, good numbers of rust-resistant varieties are available for different agro climatic zones. The farmers are advice to spray the following three fungicides i) Tebuconazole 250EC (Folicur) @ 0.1 per cent (1 ml / litre) ii) Propiconazole (Tilt) 25 EC @ 0.1 per cent (1 ml / litre) iii) Triademefon (Bayleton 25WP) @ 0.1 per cent. At the initial appearance of yellow rust one ml of chemical should be mixed in one litre water and thus 200 ml of fungicide mixed with 200 L of water should be sprayed in one acre wheat crop. If need, farmers are advised to repeat the spray. Spary should be done when weather is clear i. e. no rain, no fog / dew etc. It is recommended 2-3 sprays of Tilt (Propiconazole) at fortnightly intervals to protect the wheat crop from this disease which causes a severe loss to the crop in the district. this disease appears in circles in the field and the farmers should apply the recommended doses of chemicals in the field. He further suggested that farmers should regularly visit their wheat fields so that disease infestation can be managed in the beginning. He also suggested some disease resistant varieties of wheat.