b DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



6 acres were sprayed with tobacco extract No. I. An acre was left 

 unsprayed in the middle of this block. 



A gasoline-engine sprayer outfit was used to make the application. 

 The " trailer" method of application was employed. 



About 15 per cent of the nymphs of the first brood had developed 

 wings when tins spray application was made, July 11 and 12. Nearly 

 all of the nymphs were about full grown and it was thought desira- 

 ble to use a stronger dilution than in the foregoing experiment. The 

 tobacco extract No. I was used at a dilution of 1 gallon to 100 gallons 

 of water. A pressure of about 125 pounds was maintained through- 

 out. Two leads of hose were used and about 275 gallons of liquid 

 were applied per acre. 



Within about three weeks after the application was made the dif- 

 ference in injury on the sprayed and unsprayed grape leaves became 

 noticeable. Upon the unsprayed vines the winged adult " hoppers" 

 were very numerous and the leaves were commencing to turn brown 

 and only a small amount of new growth was being made. 



Upon the sprayed vines, on the other hand, the number of winged 

 adults was noticeably much smaller, the foliage was dark green and 

 healthy, and the new growth of vine was quite thrifty throughout 

 the growing season. When the fruit commenced to ripen it became 

 quite evident that the berries and the clusters would be smaller and 

 the fruit not so purple in color upon the unsprayed vines as upon 

 those that were sprayed. Plate II, figure 1, shows a vine in the 

 unsprayed plat. Plate II, figure 2, shows a vine in the sprayed plat. 

 When the crop was harvested the sprayed plat yielded 128 baskets 

 of grapes per acre more than the unsprayed plat. This fruit was 

 sold at 10 cents per basket, giving a gross cash gain of $12.80 per acre. 

 The cost of spray material and labor of making the application 

 against this pest was as follows: 



Team and driver per day $4. 50 



Two men to apply spray, $1.75 per day 3. 50 



Tobacco extract No. I, 275 gallons per acre 2. 33 



Six acres sprayed per day, cost per acre 3. 66 



Increased cash yield per acre, sprayed plat 12. 80 



Cost of material and application per acre 3. 66 



Cash increase per acre on sprayed vines .• 9. 14 



Thus the net yield on the sprayed plat after deducting all expense 

 of labor and material was $9.14 per acre. In addition to this increase 

 in crop yield the sprayed vines made a more vigorous and healthy 

 growth than did the unsprayed vines, and the fruit was of much 

 better quality. 



