TWENTY-FIRST ANNUAL MEET INC. 205 



sulfate or "copperas" added at the rate of 34 pounds per 50 

 gallons of 1.01 solution. The process also was entirely ef- 

 fective in eliminating spray injury with each of the three 

 arsenicals this past year, as seen in Table II, by coiu paring 

 plots 7 to 9 with the similar unprecipitated plots, 4 to 6. 

 The resulting materials, howe^"er, are very disagreeable to 

 handle on account of their extremely tenacious and black- 

 ening qualities. They also seriously discolor the fruit, and 

 in our experiments they apparently reduced somewhat the 

 effectiveness of the arsenicals. Thus where the check 

 showed 13.2% curculio injury, three precipitated plots aver- 

 aged 7.6%, while the similar unprecipitated plots averaged 

 only 5.1%. The influence of precipitation and of form of 

 arsenical is shown in detail in Table II. 



TABLE II. 



Spray Injury on Fruit and Foliage of Peaches, 1911. 

 (Maximum Injuries Observed in Our Experiment of 1911). 



Per ct. Per ct. 



Corrected Fruit Leaf 



Fruits in Per cent Per cent Drop, Drop, 



Plot. Treatment. Sample. Injured. Injured. Est'd. Est'd. 



1. Check 409 5.87' 



2(a). Self-boiled, arsenate and Shot- 



L-S (1.003) 412 8.01 2.14 holes 



3. Self-boiled and arsenate 453 8.39 2.52 .7 2-2> 



4. L-S (1.003) and arsenate 428 18.22 12.35 4. 3-5 



5. L-S (1.003) and arsenite 509 24.36 18.49 15. 50 



6. L-S (1.003) and ortho- 



arsenate of lead 429 6.06 .19 .8 1 



7. L-S (1.01), iron sulphate 



and arsenate 431 5.57 



8. Same as 7 exc. arsenite. 473 5.92 .05 



9. Same as 7 except ortho- 



arsenate 416 6.02 1.15 



10. Atomic sulphur and ar- 

 senate 488 8.61 2.74 5-6 



11. Bordeaux (^-6-50) and 



arsenate 475 24.42 18.55 17. 2-3 



13. Check 398 7.79' 1.92 8. 1-2 



^ The spray injury shown in check plots 1 and 13 of this column is due to 

 the fact that the whole experiment was inadvertently sprayed by workmen during 

 our absence, with a combination of lime-sulphur and lead-arsenate that proved very 

 harmful, although the fungicide in their spray was used at about one-third the 

 strength that we were applying with comparative safety. The etTect of this out- 

 side application is corrected so far as possible in column 3, by subtracting from 

 all the plots the per cent of injury shown in plot 1. The remaining injury in 

 plot 13 is due to a second slight interference that affected only this plot. 



