Gupta, R., & Singh, M. 2002 Susceptibility of apple cultivars to the San Jose scale, Quadraspidiotus perniciosus Comstock, and its control in Kinnaur district of Himachal Pradesh.. Pest Management and Economic Zoology 10(2): 187-192.

Notes: The susceptibility apple (Malus domestica [M. pumila]) cultivars Golden Delicious, Red Delicious, and Royal Delicious, and crab apple (Malus sp.) to the San Jose scale, Q. perniciosus [Diaspidiotus perniciosus], and the efficacy of chlorpyrifos, oxydemeton-methyl and fenitrothion was evaluated in Himachal Pradesh, India, during 1999 and 2000, respectively. Golden Delicious was more susceptible (28.61 scales/fruit) to D. perniciosus compared to Royal Delicious (16.40 scales/fruit), Red Delicious (17.83 scales/fruit) and crab apple (19.23 scales/fruit). Scale populations were found more on the top portion of trees than on lower portions. Hindustan Petroleum Spray Oil 2% (HPSO) mixed with chlorpyrifos (0.02%) registered the maximum suppression of the scale (8.67% fruit infestation; 1.09 scales/fruit) compared to the untreated check (88% fruit infestation; 20.04 scales/fruit) when spraying was carried out at green-tip stage. Addition of oxydemeton-methyl (0.05%) or fenitrothion (0.05%) to HPSO did not enhance the efficacy of the spray oil.