76 AGRICULTURE OF MAINE. 



Spray; and furthermore, the Hme is bulky, fluffy, and helps in 

 the spreading properties of the dust. To illustrate that : We 

 never have much codling moth on our pears, and I thought, for 

 an experiment. I would dust some pears with a mixture made 

 of five pounds arsenate of lead and ninety-five pounds of 

 hydrate of lime, and when I went out to dust with that mix- 

 ture I found it was so light and fluffy that we could not get on 

 enough. I had to add gypsum which is a little bit heavier, and 

 I had to add a little bit of sulphur in order to give it body 

 enough so that we could make an application. Now, with 

 tobacco, the snuff' is very light and fluffy, and with tobacco you 

 will find, probably, that a little sulphur or a little gypsum is 

 necessary rather than so much lime, because the lime and 

 tobacco being fluffy, make a very light mixture that it is a 

 little difficult to blow. 



Mr. Sweetser: What sort of weather conditions do you 

 require for using the dust spray? 



Mr. Mitchell: The weather conditions for dusting are 

 exactly the same as those for spraying. As I illustrated with 

 fungus, the seed will not germinate until it gets a drop of 

 moisture. It is important for us to get on the spray immedi- 

 ately before the water and the spore cooperate to get into the 

 leaf. Therefore, often it is necessary for a fruit grower to 

 spray just before a rain. He has to watch weather conditions 

 and try and beat the rain. Now, in spraying, you know if it 

 rains your spray washes off a little, in fact, it washes oft 

 almost as fast as you put it on, and it is disagreeable to work 

 in the rain, and although you can spray against the wind it Is 

 very difflcult. very unpleasant, and you seldom get a good 

 application. Dusting is exactly the same. You can dust when 

 it is raining, but it is not a pleasant job and the dust washes 

 oft' — not entirely, but it washes oft some, just as spray does. 

 You can dust against the wind about as well as you can spray, 

 but it is very disagreeable and you do not get a good appli- 

 cation. The matter of dew has often been spoken of and, 

 personally, I prefer to dust trees when there is dew on them, 

 but all the experiments and all the observations that men 

 have made have gone to show that the dew has no practical 

 influence on the sticking qualities of the dust ; that the dust 



