Epidemiology and management of flag smut Urocystis agropyri Preuss Schroet of wheat

Abstract

newline The investigation entitled Epidemiology and management of flag smut (Urocystis agropyri (Preuss) newlineSchroet.) of wheat was conducted at the Department of Plant Pathology, CSK HPKV, Palampur and newlineResearch Sub Station, Akrot during 2018-21. The average disease incidence at different locations of newlineHimachal Pradesh varied from 2.11 to 17.77 per cent during two consecutive years. Based on molecular newlinecharacterization, the pathogen was confirmed to be Urocystis agropyri. The maximum spore germination newline(18.92 %) was recorded after 8 months of inoculum burial in soil while, no germination occurred till 4 newlinemonths of storage due to the spore dormancy. Inoculation of germinating seed with dry inoculum at 10 g newlineinoculum/ kg seed proved to be the best method to incite disease with highest incidence of 58.18 per cent. newlineInoculum load of 20 g inoculum/ kg seed adversely affected the seed health parameters like germination newlinepercentage and vigour index of seed as well as growth rate and dry weight of the seedlings with 13.70, newline52.96, 54.41 and 6.73 per cent reduction, respectively. However, the maximum reduction in speed of newlineseedling germination/ emergence (15.01 %) was found at 17.5 g inoculum/ kg seed. The maximum incidence newlineof disease (44.87 and 40.64 %) was recorded at soil moisture and temperature of 30 % and 22and#8451;, newlinerespectively. Among the weather parameters, the maximum and minimum temperatures were the most newlineimportant factors for disease development as an increase in the temperature from 11.78 - 22.75and#8451; at newlinePalampur and 09.20 - 26.13and#8451; at Akrot increased the disease incidence during both the years. The disease newlineincidence was found to be maximum (13.28 and 16.47%) in 15th November sown crop at Palampur during newlineboth the years. While, at Akrot, it was maximum in 15th November sown crop (25.50 %) during 2019-20 and newlinein 30th November sown crop (37.49 %) during 2020-21. Out of 210 wheat germplasm lines/ genotypes, 71 newlinewere found immune, 45 as highly resistant and 34 as moderately resistant. The late sowing of wheat was newlinefound to be the best with minimum disease incidence of 10.79 per cent followed by early sowing (21.47 %). newlineThe sowing depth of 2 cm showed minimum disease incidence of 12.98 per cent. Among the tested organic newlineamendments, Jeevamrit at 10 ml/ kg soil gave the maximum reduction (82.94 %) in the incidence of flag newlinesmut. While, amongst biocontrol agents as seed and soil treatments, resident Trichoderma viride at 10 g or newlineml/ kg seed or soil was found to be most effective against the disease with maximum reduction of 47.50 and newline34.02 per cent, respectively. From botanicals, the seed treatment with aqueous extracts of Eucalyptus newlinetereticornis at 15 % concentration was found to be the best with maximum disease control of 79.44, 71.85, newline80.30 and 77.55 per cent under two approaches of pathogen inoculation in pot and field experiments, newlinerespectively. Among fungicides, tebuconazole 060 FS at 1, 2 and 3 ml/ kg seed, carboxin 37.5% + thiram newline37.5% DS, carbendazim 50 WP and carboxin 75 WP at 3 g/ kg seed were found most effective giving newlinecomplete control of the disease under both the approaches of pathogen inoculation in pot and field newlineexperiments. The integration of tebuconazole 060 FS at 1 ml/ kg seed with Jeevamrit at 10 ml/ kg soil (as newlinesoil treatment); E. tereticornis at 15 % concentration (as seed treatment); and soil treatment with Jeevamrit newlineand seed treatment with E. tereticornis gave complete control of the disease. On the basis of morphological newlineand molecular characterizations, 17 isolates of U. agropyri were grouped into four groups each i.e. FSG 1 to newlineFSG 4 and FSV1 to FSV4, respectively. The group FSV 1 and FSV 2 were further subgrouped into six newlinesubgroups i.e. FSV 1a, FSV 1b, FSV 2a, FSV 2b, FSV 2c and FSV 2d