106 



DECIDUOUS FEUIT INSECTS AND INSECTICIDES. 



SPRAYING EXPERIMENTS AGAINST THE LARV^. 



The experiments against the larvae were conducted in the Davis 

 orchard at Canon City, Colo. This orchard consisted of many varie- 

 ties, namely, Ben Davis, Missouri Pippin, Winesap, Paragon, Jeniton, 

 Rome Beauty, Jonathan, Maiden Blush, Yellow Transparent, and 

 Red Astrakhan. There were also a few trees of other varieties. 

 The orchard as a whole had no more than a good one-fifth crop. 

 On account of the light crop it was difficult to determine fairly the 

 results of the spraying on some plats. In all cases the material was 

 applied with a good gasoline-power outfit and a pressure ranging 

 from 150 to 200 pounds was maintained. The plats contained trees 

 as follows: I, 155; II, 72; III, 31; IV, 63; V, 46; VI, 38; VII, 26; 

 VIII, 30; IX, 41; X, 6. 



The results are shown in Table VI. 



Table VI. — Spraying experiments against the larvx of the fruit-tree leaf-roller, Canon 



City, Colo., 1912. 



Plat 

 No. 



Treatment. 



Percent- 

 age of 

 injured 

 apples. 



Percent- 

 age of 

 sound 



apples. 



Condition of foliage. 



I 



II 



III 



IV 



V 

 VI 



VII 



VIII 



IX 



X 



Two applications of arsenate of lead, 3 pounds 

 to 50 gallons of water, May 2 and May 17 and 

 18. 



Two applications of arsenate of lead, 3 pounds 

 to 50 gallons of water, plus 4 ounces Paris 

 green. 



Two applications of arsenate of lead, 3 pounds 

 to 50 gallons water, plus 40 per cent nicotine 

 solution (1:1,000), May 3 and 25. 



One application of arsenate of lead, 3 pounds 

 to 50 gallons water, plus 40 per cent nicotine 

 solution (1:1,000), May 3. 



Two applications of arsenate of zinc, 1 pound 

 to 50 gallons water, May 11 and 25. 



One application of Paris green, 8 ounces to 50 

 gallons water, plus 2 pounds lime, May 4; 

 one application of Paris green, 1 pound to 

 50 gallons water, plus 2 pounds lime, May 18. 



One application of 40 per cent nicotine solu- 

 tion at 1:800, plus 2 pounds of soap, May 11. 



One application of 40 per cent nicotine solu- 

 tion at 1:800, plus 2 pounds of soap, May 18. 



One application of 40 per cent nicotine solu- 

 tion at 1:1,000, plus 2 pounds of soap, May 18. 



Check; unsprayed 



20.00 



80.00 



20.00 



80.00 



15.00 



85.00 



15.00 



85.00 



25.00 



75.00 



18.00 



82.00 



) crop. 



No crop. 



35.00 



65.00 



40.00 



60.00 



98.00 



2.00 



Good; no arsenical injury. 

 Do. 



Very good; no arsenical in- 

 jury. 



Do. 



Fair; serious arsenical in- 

 jury. 



Good; slightly burned by 

 arsenical. 



Fairly good. 

 Fair. 



Do. 

 Trees nearly defoliated. 



Note.— Plats I, IV, VII, VIII, and IX were sprayed with arsenate of lead at the rate of 3 pounds to 50 

 gallons of water for the codling moth when the petals had dropped. Plats II and VI received the same 

 treatment for the leaf-roller as for the first codling-moth application. 



The damage to fruit was determined by making careful counts of 

 fruits from various trees in the different plats. The total number of 

 fruits was not counted in any case, so the percentages given are only 

 approximate. On Plat VII there was a total crop failure. 



As will be noted, the best results were obtained on Plats III and 

 IV, where a combination of arsenate of lead (3;50) and 40 per cent 

 nicotine solution was used. The 40 per cent nicotine solution was 

 found to be effective only when the larvae were quite small. It was 



