G-Journal of Environmental Science and Technology (Aug 2013)
Varietal screening of rose (Rosa x hybrida) cultivars and in vitro efficacy of fungicides against black spot disease (Diplocarpon rosae Wolf.) in Arunachal Pradesh condition
Abstract
Rose varieties were evaluated in field against Diplocarpon rosae cause of black spot disease of rose. Black spot resistance was visually evaluated for thirty seven rose varieties against D. rosae. Out of thirty seven varieties evaluated, none of the varieties were found immune, very highly resistant, highly resistant, resistant and moderately resistant. However, three varieties namely Paradise, Shabnam and Pixie showed moderately susceptible reaction. Whereas, eleven varieties viz., Angelica Renae, Atago, Folklore, Granada, Hot Cocoa, Mardigrass, Midas Touch, Mrinalini, Revival, Tipus Flame and Victor Hugo showed susceptible reaction. Twelve varieties viz. Baccardi, Claudia Ribond, Charles Mallerin, Crimson Lace, Dr. Pal, Impatient, Madam Dulbourde, Marcopolo, Melody, Rainbow End, Sonia and Sugandha were responded highly susceptible reaction at 75 per cent disease severity. Whereas, eleven varieties namely Angelique, Christian Dior, Gemini, Gladiator, Golden Jubilee, Priyadarsini, Sand. Centenary, R. R. M. Roy, Sweet Promise, Unforgotten and Vale of Cloyd were highly susceptible reaction at 95 per cent disease severity. Further, five fungicides [three systemic fungicides namely Carbendazim, Hexaconazole (Contaf) & Ridomil MZ 72 WP and two contact fungicides viz. Blitox-50 and Mancozeb] were evaluated in vitro for the management of D. rosae. Hexaconazole (Contaf) was found to inhibit the mycelial growth of D. rosae significantly at a concentration of 200 ppm and 250 ppm followed by Ridomil MZ 72 WP at same concentration.
