tailieunhanh - Reaction of onion varieties to stemphylium blight (Stemphylium vesicarium)

Twenty one onion varieties were tested during 2017-18 at Pantnagar, Uttarakhand for evaluating their resistance levels against Stemphylium blight disease of onion caused by Stemphylium vesicarium (Wallr) Simmons under field and glasshouse conditions. The disease has emerged as a serious problem to onion growers all across the country including the tarai region of Uttarakhand. Disease occurred by natural infection in field while artificial inoculation was carried out in glasshouse. Disease severity was recorded when the typical disease symptoms had developed in field and 10 days after inoculation in glasshouse. Disease rating was done based on 0-5 rating scale and percent disease index was calculated. None of the 21 varieties screened was free from the disease. However, there were significant variations among the varieties under study. Results revealed that variety Bhima Shweta exhibited the least PDI among all the tested cultivars and displayed moderately resistant (MR) reaction to Stemphylium blight under glasshouse condition. Two other varieties viz. Arka Niketan and Bhima Shakti also showed less disease severity as compared to all other varieties, while still falling in the moderately susceptible category. The variety Poona Red Desi was found to be susceptible (S) to Stemphylium blight in field as well as glasshouse. All the tested varieties lied under the moderately susceptible (MS) category. | Reaction of onion varieties to stemphylium blight (Stemphylium vesicarium)