EVALUATION OF SPRAY COVERAGE OF MISCIBLE OIL ON CITRUS TREES BY MEANS OF AERIAL AND GROUND APPLICATIONS

The present work was carried out to evaluate the quality of spray produced by Mi-2 helicopter and conventional motor sprayer using rates of application 40.0 and 2400 L/fed, respectively. A summer oil (Masrona super oil) was used for controlling red scale insect, Aonidiella aurantii (Order : Homoptera Fam : Diaspididae) and the white fly, Dialeu­rodes citri (Fam : Aleyrodidae) on sweet orange trees. Due to sufficient down wash created by the helicopter, good spray coverage coinciding to a great extent with the distribution of infestation on the treated trees resulted. The spectrum of oily droplets deposited on citrus trees was bigger in size with 11% and with about 50% less in number than the watery droplets that were recorded under airstrip conditions due to the viscosity factor. The average size and number of droplets collected un­der airstrip and orchard conditions were 340, pm-60 droplets/cm2 and 443, pm-33 droplets/cm2, respectively. The C.V. % of droplets distribu­tion number on spray collectors was 48%. The total spray lost on ground with aerial and ground application was 15% and 75%, respectively. A positive correlation was found be­tween aerial spray coverage and the control of red scale insect wher mortality percentage increased 1% more by increasing the droplet size with 4.0 pm. The daily performance of motor sprayer and Mi-2 helicopter was about 3.0 and 500 fed./day, successively. The price of aerial spray­ing of one feddan by aerial means was cheaper by about 56% than the price of motor sprayer. In additon to reducing dose amount with low vol­ume spray by helicopter to the fifth in comparison with motor sprayer. In general the helicopter was superior in controlling red scale insect on cit­rus than ground motor sprayer.