Studies on the currendt status on San Jose scale quadraspidiotus perniciosus (Comstock) and its management on apple

Survey on the pest incidence and severity of San Jose scale (Quadraspidiotus perniciosus) was conducted during 2004 in thirteen blocks of district Baramulla and three blocks of district Srinagar. The results revealed highest mean incidence of 27.4 per cent at location Ajas (karewa) among both the altitudes of district Baramulla. Among the blocks the highest (24.25%) and lowest (5.6%) mean pest incidence was recorded in Hajan and Bandipora blocks whereas highest (7.98%) and the lowest (1.37%) mean per cent pest severity was recorded from Pattan and Bandipora blocks respectively. The observations from district Srinagar on the basis of pest incidence and severity of the San Jose scale revealed that mean per cent incidence was 16.85 per cent at location Nunar (low lying). Among the blocks, the highest (16.85%) and lowest (12.5%) mean pest incidence was recorded at Ganderbal and Lar blocks respectively, whereas highest (6.14%) and lowest (4.08%) mean per cent severity was recorded from Ganderbal and Srinagar blocks, respectively. Highest twig infestation (live/dead) both in managed and unmanaged orchards, was recorded (12.11/cm2) on 15th August and lowest infestation (2.17/cm2) on 15th April. For the management of the pest on apple field and laboratory experiments were conducted to study the effectiveness of five mineral oils viz., D.C. tron plus, P.D. spray oil, H.P. spray oil, Atso spray oil and diesel oil alone at 2% and in combination with chemical pesticides viz., endosulfan (0.05%), ethion (0.05%), chlorpyrifos (0.025%), dimethoate (0.03%), and quinalphos (0.03%) used at one-half green tip stage of the crop. Maximum number of live San Jose scale 60 DAT (day after treatment) was recorded (10.62/cm2) in combination Atso spray oil + endosulfan while least number (4.90/cm2) in combination P.D. spray oil + quinalphos. In oils alone maximum number of (12.27) was observed in D.C. tron plus. The per cent mortality worked out on the basis of live scales over pre-treatment, recorded at 10, 20, 40, 50 and 60 days after application of treatments, was significantly effective against the pest. However, these treatments varied in their efficacy at these intervals and some of these proved to be at par with one another in their efficacy against the pest. Among oils highest per cent mortality of 59.20 was observed in H.P. spray oil and least 49.17 per cent in D.C. tron plus. Among combinations highest mortality of 78.53/cm2 was recorded in P.D. spray oil + quinalphos and least mortality percentage (54.44 cm2) in combination Atso spray oil + endosulfan. It was observed that in all the treatments, the residual effect remained upto 50 days after application, because increase in the scale population was observed after 60th day post count. Observations recorded to find the impact of these oils and chemicals on the natural enemies of the San Jose scale revealed that highest population of parasitoids (Aphytis sp., Encarsia perniciosus) was recorded with P.D. spray oil + ethion of 2.55/15 cm2 and least recorded (0.11/15 cm2) in D.C. tron + chlorpyrifos. The zero per cent incidence of the San Jose scale on fruit after the application of treatments was recorded in oil H.P. spray oil whereas similar severity was also recorded in oil H.P. spray oil