450 STATE BOARD OF AGRICUL.TURE. 



A 200-gallon tankful of each of these combinations was used and the trees 

 were covered as thoroughly as was possible for one man working from the 

 ground with a spray gun. These materials were applied to a section of 

 Block B and at least half the block was not sprayed at that time. 



The results from the use of all these materials were very marked. The 

 hydrated lime alone killed practically all the nymphs which were on the sur- 

 face of the leaves but did not kill many of those feeding around buds or at 

 the base of leaf stems on tender growth. All of the combinations in which 

 Black Leaf 40 was used gave satisfactory results and almost completely 

 eradicated the psylla from the trees treated with them. There was a strong 

 contrast in the condition of the trees sprayed in June and the surrounding 

 trees not sprayed at that time. This difference in condition was apparent 

 until late in the season. The adult psyllas had then spread into this sprayed 

 section of the orchard, from the section not sprayed in' June, in such numbers 

 as to cause serious injury during September. 



Practically all mature trees in all parts of the orchard were badly defoliated 

 by the injury from a large brood of nymphs which developed in early Sep- 

 tember. 



Remarks. It is impossible to tell exactly why the results in this orchard 

 were not satisfactory, but the failure to cover all portions of the trees with 

 spraying material, particularly at the calyx appHcation, was undoubtedly 

 an important reason why the control was not satisfactory. The owner of 

 the orchard and others who followed the work closely agree that the spraying 

 was not really done as thoroughly as was thought at the time of application. 



ORCHARD NUMBER 2. 



This orchard is in the South Haven district. The trees are Kieffer about 

 seven or eight years old. This orchard was sprayed very thoroughly about 

 March 15 with strong lime-sulphur and Black Leaf 40 to kill the hibernating 

 adults. The trees were examined on March 24 and many active adults were 

 found. It is believed that these had migrated to the p^r trees from other 

 hibernating quarters after the application was made, especially when the 

 thoroughness with which the spraying was done is considered. 



ORCHARD NUMBER 3. 



This orchard is an extensive planting near Fennville of mature, closely 

 set trees of several varieties. There was a very heavy infestation of psylla 

 in the fall of 1920 and great numbers of eggs were deposited on these trees in 

 late March and early April of 1921. The orchard was sprayed just before 

 blossoming with lime-sulphur, 63^-50. The application was begun when the 

 blossom buds of Kieffer were mostly separated, but the spraying was not 

 completed until the later blooming varieties were in full pink. There were 

 prospects for only a light crop of fruit so little consideration was given to the 

 effect of the sprajdng material upon the flower buds. Another application 

 was made about one week after the petals fell, using Black Leaf 40 in com- 

 bination with dilute lime-sulphur and lead arsenate. Both applications were 

 made in a thorough manner. 



Results. These two thorough applications gave almost complete control 

 of the psylla and it was very difficult at any time during the entire season to 

 find psylla in any form. The orchard was last visited in early October and 

 at that time the foliage was in excellent condition. Another item of interest 



