448 STATE BOARD OF AGRICULTURE. 



various concentrations to determine which one would be most effective in 

 killing the eggs. A report of this work is not desirable here except that the 

 results of this work indicated that lime-sulphur solution, 6)^-50, is effective 

 for killing psylla eggs. Similar results have been obtained by workers in 

 other districts.* The recommendation that lime-sulphur solution, 63^-50, 

 be used for killing psylla eggs was then made by the Sections of Entomology 

 and Horticulture. 



Field observations. In order to know how successful growers were in con- 

 trolling pear psylla by this and other methods, observations were made 

 throughout the season in several orchards, most of which were in the Fenn- 

 ville district. The orchards in which observations were made will be referred 

 to hereafter by number and the spraying was in nearly every instance done 

 by the orchard owners. 



ORCHARD NUMBER 1. 



This orchard is located in the Fennville district and contains several thou- 

 sand pear trees of various varieties. The trees are mostly mature. The 

 infestation of pear psylla was very severe in one block in 1920 but not so bad 

 in the others. 



Spraying operations. The block that was seriously infested in 1920, and 

 will be referred to as Block A, was sprayed in late November, 1920, with 

 lime-sulphur, 63^-50, and nicotine sulphate (Black Leaf 40) 1 pint in 100 

 gallons. The bark of these trees was quite smooth as the trees had been 

 thoroughly scraped about one year previously. There had been no sharp 

 freeze to drive the psylla into hibernating quarters and the leaves were barely 

 off the trees at that time. The weather wasmild and continued so through- 

 out December so that the psylla were active unusually late. This application 

 was undoubtedly effective against all psyllas hit and the orchard was quite 

 free from them for about two weeks but after that time they were present 

 in increasing numbers. They probably were working back into this orchard 

 from fence rows, other kinds of trees and from a neighboring pear and apple 

 orchard just over a fence. 



Block B, which is located on another portion of the farm, was not sprayed 

 in the fall and had not been seriously infested with psylla in 1920. By early 

 April 1921, almost inconceivable numbers of eggs had been deposited on the 

 trees of this block. Eggs were much more numerous here than in Block A 

 which had been sprayed in November. 



All pear trees on the farm were sprayed between April 7 and 12 with lime- 

 sulphur, 6)^-50. At that time the blossom buds of Kieffer had mostly sepa- 

 rated in the clusters; Bartlett buds were just beginning to separate and Bosc 

 buds were much slower in opening than those of the Bartlett. The spraying 

 was all done with spray guns, with one man to each spraying outfit. Most 

 of the work was done with the man working from the ground. 



The entire orchard was again sprayed just after the petals fell for psylla, 

 using nicotine sulphate, 1 pint to 100 gallons, in combination with dilute lime- 

 sulphur or bordeaux, and arsenate of lead. 



During May when the nymphs of the first summer brood were prevalent 

 in unsprayed orchards they were found here, in both Block A and B, in limited 

 numbers, but plentiful enough to cause serious infestation from later broods 

 provided weather conditions were favorable. 



•Hodgkiss, H. E., N. Y. Agr. Exp. Sta. Bui. 387; Ross, W. A. and Robinson, W., Report Entomo- 

 logical Society of Ontario, 1919. 



