Chander, R., & Kakar, K.L. 1994 Requirement of dormant spray oil for the suppresion of San Jose scale, Quadraspidiotus perniciosus (Comstock) on apple.. Journal of Insect Science 7: 222-223.

Notes: Studies to determine the requirement of using miscible oil as a tree spray oil on the basis of fruit infestation revealed that apple orchards in Himachal Pradesh, India, with 11% fruit infestation with Quadraspidiotus perniciosus before treatment during 1989 showed no infestation during 1990, whereas 27.5% of fruits were infested on untreated trees; in 1991 1.6% regeneration of the pest was recorded from fruits of treated trees, while untreated trees had sizeable infestation (36.2%); spraying in alternate years was suggested to reduce cost and keep pest in check.