IMPORTANT ORCHARD PESTS AND SPRAY 



FORMULAE 



INTRODUCTION 



Only the leading spray mixtures are here mentioned. All have 

 merit in the control of particular insect or plant diseases. It 

 is, however, essential that care be used not only in selecting the 

 right material, but in the time and thoroughness of application. 

 !Xo spraying takes the place of orchard feeding or pruning. 



SPRAYING FOR INSECTS 



Two chief principles govern spraying for insects: 



1. Arsenical or other poisons put on foliage or immature fruits 

 will be eaten by insects which teed on the surface of the leaf or 

 fruit. Among such surface-feeding insects are currant worms, 

 apple worms, canker worms and the various forest caterpillars. 



2. Sprays which kill insects by contact with their bodies are 

 used for insects which are not surface feeders. Such insects 

 cause damage by puncturing the leaves or bark to suck interior 

 plant juices. Among these sucking insects are the various scale 

 insects, plant lice and pear psylla. Against such insects oils, 

 soaps, tobacco extracts and lime-sulphur sprays are used. Money 

 is wasted annually in attempting to control this class of insects 

 with poison spra 



Among the insects which are not within reach of either con- 

 tact or poison sprays are the pear midge, apple and cherry mag- 

 got, various borers and leaf miners. 



San Jose Scale. — This Asiatic insect of the bark louse family 

 caused damage in California for years previous to its introduc- 

 tion into eastern Unite] States. It was first found east of the 

 Rocky Mountains in 1893. This is a typical sucking insect which 

 draw- its nourishment from plants by means of the mouth parts 

 that pierce the inner tissues. Over the insect is a waxy Bcale 



[477] 



