Loose smut of wheat caused by Ustilago segetum (pers) Roussel var. tritici is one of the important diseases of wheat in India. The disease causes 1-2 percent losses in wheat production. Losses caused by this disease may be upto 5-7% in cases where the farmers recycle their own seed (DWR 1992). Since cultivated varieties lack resistance to loose smut, so chemical control of gain is important. Hence there is need to identify some new molecules that are cheaper and effective against loose smut of wheat.
The experiment was conducted at wheat breeding research area of CSHAU-Hisar-India during 2000-2002 crop seasons. The seed of wheat var. WH 147 inoculated with 20% loose smut infection for testing. The plot size was of 6 lines and 2 m length in triplicate randomized block design. The treatment of tested molecules were Dividend 3%WS (difenoconazole) @ 1.0, 2.0, 2.5, 3.0 g/kg seed, Pulsor 2F (thifluzamide) @ 1.0, 1.5, 2.0, ml/kg seed, Vitavax 200FF (carboxin) @ 2.0, .3.0 ml/kg seed, Vitavax 200WP (carboxin) @ 2.0,3.0,4.0 g/kg seed, Raxil 2DS (tebuconazole)@ 0.5,1.25 g/kg seed, Vitavax 75WP (carboxin) and Bavistin 50WP (carbendazim) both @ 2 g/kg seed as presowing dry and slurry treatment of fungicide in comparison to cheek. The crop was raised as per recommended agronomic practices. The smutted and healthy tillers/plot were counted and percentage of smutted tillers was calculated on tillers basis.
All fungicides controlled loose smut incidence Seed treatment of Raxil 2DS and Dividend eradicated the disease upto 99.5 and 83.9 percent, respectively in comparison to recommended fungicides Vitavax 75WP (2g/kg) controlled upto 91.6 percent. Pulsor 2F, Vitavax 200FF, Vitavax 200WP reduced the disease 48.9 to 83.3% depending upon the dose. There was no phytotoxicity observed in none of treatment. The present studies clearly indicated that Raxil 2DS can be used at lower dose ie @ 0.5 g/kg seed quite effectively. It is concluded that Raxil 2DS and Dividend 3%WS may be used in addition to carboxin and carbendazim for controlling the loose smut of wheat. The effectiveness of Raxi 12DS in controlling loose smut at the rate of 0.2% has been reported by Sinha and Singh (1996) and Goel et al. (2001).
References
DWR Karnal (1992) Project Director's Report 1991-92: 1-8. All India Coordinated
Wheat Improvement Project. Directorate of Wheat Research, Karnal.
Goel LB, Singh DP, Sinha VC, Amerika Singh, Singh KP, Tewari AN, Beniwal MS, Karwasra SS, Aujla SS and Grewal AS (2001) Efficacy of Raxil (tebuconazole) for controlling the loose smut of wheat caused by Ustilago segetum var. tritici. Indian Phytopath. 54(2): 270-271.
Sinha VC and Singh DP (1996) Tebuconazole in the control of loose smut of wheat. Indian Mycol Plant Path 26: 279- 281.