358 IiFFORT OF THE DEPARTMENT OF "RnTOMOLOOY OF TTTF 



Fig. 31. Condition of clus- 

 ter buds for effective 

 spraying for psylla eggs. 



of steadily decreasing temperatures at this season on the move- 

 ments of the flies makes them especially vulnerable to spraying. 

 In planning for thib work select days when there is no danger of 

 the spraying mixture freezing on the trees. The most satisfactory 

 spray from the standpoints of safety to fruit and leaf buds and 



effectiveness against the insect is three-fourths 

 of a pint of Black Leaf 40 to one hundred gallons 

 of water to which are added from three to five 

 pounds of dissolved soap. (Formula 1.) It is 

 also advisable to remove the loose and rough 

 bark to discourage the flies from wintering on 

 the trees and to render them more exposed to 

 spraying mixtures. This operation may be done 

 at a convenient time but the bark is more easily 

 detached following a wet period. To avoid infec- 

 tion with disease care should be taken not to cut 

 into live tissues. 



2. Spraying for eggs of winter flies. — The eggs 

 about to hatch and the newly-emerged nymphs 

 succumb to an application of the lime-sulphur mixture. In this lies 

 a hint to the fruit-grower for an effective use of this spray against 

 the psylla as well as the scale. The eggs of the psylla are laid prin- 

 cipally during April and commence to hatch early in May or when the 

 blossom cluster-buds are beginning to separate at the tips. (Fig. 31.) 

 Most growers spray much earlier than this for the San Jose scale, 

 but by postponing the treatment 

 of pear orchards until the blossom 

 clusters are well advanced one may 

 deal another effective blow against 

 the psylla and with the same treat- 

 ment successfully combat the scale. 

 The lime-sulphur solution, testing 

 32°-34° B., should be diluted in the 

 proportion of one gallon to eight or 

 nine gallons of water. (Formula 2.) 

 The spray should be used in liberal 

 quantities and pains should be 

 exercised to wet all portions of the 

 tree, especially the fruit spurs and 

 the under sides of the young wood, 

 where most of the eggs are laid. 



3. Spraying for the first-brood nymphs. — A third opportunity to 

 strike hard at the psylla is when all of the eggs have hatched and 

 the young nymphs are largely assembled in the axils of the young 

 leaves and fruits. This occurs normally during the latter part of 

 the blossoming period and the young insects can be reached by 



Fig. 32. Conditions of blossom clusters during 

 the spraying for psylla nymphs. 



