464 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



observed. Many of the small buds on the larger limbs which in time 

 would develop into fruit spurs were killed, with a result that in the 

 forming of new buds and the resulting foliage growth, the development 

 of the leaves on the plats seemed several weeks behind that of the 

 checks. Today, however (July 20) little or no visible difference in 

 the amount of foliage and fruit exists between sprayed and check 

 trees. In fact (perhaps my imagination) many of the sprayed trees 

 appear more vigorous and possess a richer green coloration than is 

 found in the checks. Just what effect this burning of the fruit spurs 

 will have on next year's crop is a point of interest that will be watched 

 keenly during this fall and next spring. 



By referring to the table, the results that were obtained in the 

 miscible oil experiments will be noted. Egg counts were made to 

 determine the ovicidal properties of the various strengths, and fruit 

 counts were made to determine the percentage of injury caused by 

 the surviving worms. ^ It might be added at this point that the infes- 

 tation was not as severe in the oil plats as was found to occur in the 

 arsenate of lead experiments though both series were carried on in the 

 same orchard. The only explanation that can be offered is that the 

 Newtown appears to be more resistant to roller attack than the Spitz- 

 enburg. Owing to the fact that it was adjudged unsafe to apply the 

 oil to the Spitzenburgs on account of the advanced foliage condition, 

 Newtowns, whose development is more tardy, were substituted. 

 The infestation here was- about two thirds as severe as that existing 

 in the arsenate of lead experiments. 



All of the miscible oil applications proved to be decidedly efficient as 

 agents in killing the leaf -roller eggs. In checking up the experiments 

 it was found that the numbers of hatching eggs taken from the different 

 plats varied directly with the strengths of oil used. These same 

 variations, though of very narrow margins, were found to exist when 

 the fruit counts were made. 



In experiment 11, where 5 gallons to 100 were used, 92.1 per cent 

 of the roller eggs failed to hatch. In the check rows (two rows left 

 across the orchard on either side of which were two experimental 

 plats), 96.8 per cent of the worms emerged. When the countings 

 were made to determine the fruit injury it was found that the worms 

 that escaped the oil caused a 3.6 per cent injury. On the check rows, 

 18 per cent of the apples were damaged by the worms. In increasing 

 the oil to 6 gallons to the 100 in experiment 12, the efficiency increased 

 from 92.1 per cent to 98.8 per cent. In this experiment, 2.9 per cent 

 of the apples were injured by rollers or a very slight decrease from 

 that noted in number 11. 



