20 



two rows of trees, and the difference in results was evidently due to 

 the absence of Bordeaux in the one case and its presence in the other. 

 This would explain the ineffectiveness of the usual orchard-spraying pro- 

 gram in controlling the apple flea-weevil as it is the custom to combine 

 fungicides with the arsenical in the spray mixture. 



Supplementary applications of arsenical sprays. — In an orchard 

 which had been sprayed according to the regular schedule for the cod- 

 ling-moth eight trees were given an additional or supplementary spray 

 according to the following formula : 



Arsenate of lead paste 3 lbs. 



Flour 8 lbs. 



Water 50 gal. 



The spraying was done at a pressure of 150 lbs. with a Friend 

 45°-angIe nozzle, one hose being operated from the tower and the other 

 from the ground, a special effort being thus made to cover both surfaces 

 of the leaves. On the following day 647 dead beetles were counted on 

 90 square feet of canvas spread under one of the trees. Verj' few 

 weevils remained on the trees receiving the extra spraying, though they 

 were present in large numbers on adjoining trees which had received 

 the spray of the normal program. On the second day following the 

 application an average of but one weevil was found to every 24 leaves 

 on the extra-sprayed trees, and one on every 6 leaves of those adjoining 

 — a reduction of about 75 per cent, in the number of weevils because 

 of the spray. Eight days after the application the extra-sprayed trees 

 had an average of one weevil to 29 leaves, and the others had one weevil 

 to 6 leaves. The infestation was decreasing on the extra-sprayed trees 

 but not on those not sprayed, although the fonner were exposed to 

 reinfestation from their neighbors. 



Spraying both the upper and lower leaf-surface vs. spraying the 

 upper surface only. — Adjoining the plot of eight trees just discussed, in 

 which both surfaces of the leaves were sprayed, an eight-tree plot was 

 sprayed at the same time with the same mixture, but in this only the upper 

 surface of the leaves was covered. Two days after the application there 

 was an average of one weevil to 13 leaves on the sprayed side, and one 

 weevil to 5 leaves on the unsprayed side. The sprayed side of the leaves 

 was thus much less infested than the unsprayed side, and the leaves 

 sprayed on both sides were still less so, since, as will be recalled, these 

 averaged one weevil to 24 leaves. This difference seems sufficient to war- 

 rant spraying both sides of the leaves if this supplementary application 

 of an arsenical is made without the addition of a fungicide. 



Tests of different poison formulae. — Two series of tests were made 

 to determine the value of different arsenical combinations, a spray giin 

 being used to throw the spray upward through the tree, and thus to 

 cover both leaf surfaces. 



