38 PROTECTION OF PLANTS — 1922-23 



crop they would have had 5,000 barrels more fruit and 20 per cent more of 

 that "A" grade. 



Nicotine dusting has progressed to such a point that outside of the scale 

 insects, dusting gives much more satisfactory control of sucking insects than 

 spraying. Such insects as pea aphis, which could never be satisfactorily 

 controlled by spray, are now easily controlled by dust. 



Last spring the best nicotine dust was one containing a tot^l of 6 percent 

 of nicotine sulphate or 2.4 percent of nicotine. Of this 3.75 percent of the 

 nicotine present was volatile, or the total dust contained 0.09 percent of 

 volatile nicotine. This dust did fair work in the control of moderately resistant 

 insects. By the end of the season dusts containing a total of 2.4 percent of 

 nicotine and 0.26 percent of volatile nicotine were on the market. This last 

 dust contained slightly less than three times as much volatile nicotine as those 

 sold earlier in the season, but in practice one-fourth as much dust per acre 

 gave better control of sucking insects than did the earlier dusts. Today the 

 Headlee idea is being applied with the result that dusts are being made with 

 from 40 to 60 percent of the total nicotine in highly volatile form. I know 

 of one dust in particular that is being placed on the market which only contains 

 a total of 2.0 percent nicotine but 60 percent of the nicotine, or a total of 1.2 

 percent of the dust, is volatile nicotine. This dust contains less total nicotine, 

 yet it is over twelve times as valuable per pound as the best dust on the market 

 at the beginning of last season and twenty times as valuable as others. 



On ground crops you can increase the efficacy of nicotine dusting by 

 dragging a sheet for twenty feet over the crops, tying the sheet to the boom, 

 thus confining the fumes. This almost doubles the value of a nicotine dust. 



At the end of 1922 nicotine dusts were successfully controlling such insects 

 as pea aphis, potato aphis, pear psylla and other insects that have in the past 

 been almost immune to the former nicotine dusts and very difficult to control 

 by spray. 



There w'ill, in the future, be many arguments pro and con on dusting but 

 as I see it the dusting method is going to win, perhaps slowly, but it will win in 

 spite of anything that can be done to prevent it. The low cost and low up- 

 keep of a dusting machine, the speed of application, the low-priced diisting 

 materials now available and the fact that the average farmer makes a better 

 job of dusting than he does of spraying are factors that are going to cause 

 dusting to increase. 



It IS impossible for dusting to succeed with high-priced dusting materials, 

 but it has been my experience that just as soon as the cost of dusting is made 

 approximately the same as the cost of spraying, the growers are going to dust 

 instead of spray. Whether they get a few more or a few less No. 1 apples 



