83 THE REPORT OF THE No. 36 



In orchard A the Aveather during our work was continuously dry, and after 

 dusting one side of the trees I felt so certain that the mixture would not kill the 

 scale that 1 merely applied the remainder of my material to the same side and did 

 the other side very thoroughly with lime-sulphur. 



Results. To my great surprise this year no scale was found on either of 

 these plots. The fact is that we made such a cleaning up of the scale in both 

 orchards that only two scales in all were found and these might easily have been 

 introduced by a bird or insect. I am not surprised at the results from the liquid, 

 but I am surprised at those from the sodium sulphide dust. I thought that if 

 the trees Avere moist one could hope for such results, but from my observations I 

 did not hope for it when the dusting was done on dry trees. The results clearly 

 justify further tests. 



Results Obtained from Dusting Elsewhere in Ontario. 



At Guelph, Prof. Crow used the sulphur-arsenate of lead dust on his apple 

 orchard, but failed to control the scab. About 66 per cent, of Snows and 50 per 

 cent, of Spy are scabby, and other susceptible varieties are also dirty. There is 

 very little doubt that with liquid spray he would have succeeded much better. 



At Brighton an able fruit grower spent much money on dusting his large 

 orchard and gave more than the regular number of applications, but was much dis- 

 appointed with the results. Two other equally good growers not far from him 

 treated their orchards with liquid and had beautifully clean fruit, nearly 99 per 

 cent, free from scab. One of these orchards received only three applications in all. 



At Whitby about half of the Government demonstration orchard was sprayed 

 with the liquid and the remainder dusted. The results were decidedly in favour of 

 the liquid, though the utmost care was taken to do the dusting well and at the 

 right time, and though, extra applications were given in all weather favourable to 

 scab. Dusted Snow trees there had as high as 50 per cent. scab. 



Conclusions Regarding the Merits of Dust for x\pple Orchards, 



In spite of the excellent results I obtained last year and again this year, I 

 fear 'very greatly that it will be much safer to continue to use the liquid spray at 

 least for a number of years longer until improved dust substitutes or improved 

 machinery or both are available, and until a larger percentage of those who test it 

 can obtain satisfactory results. A duster could, of course, on a large fruit farm 

 help to tide over an emergency where an extra treatment must be given quickly. 

 The great weakness of the dust method in my opinion is its failing to adhere 

 sufficiently long in wet weather to the fruit and foliage. 



A Valuable Field Other Than Apple Orchards for the Use of Dust. 



Our experiments in two excellent sweet cherry orchards, each consisting of 

 about ninety large trees of several varieties, has shown a very valuable use for 

 dust. Everyone who knows much about sweet cherries knows that it is very' 

 difficult, especially in warm, moist weather, to keep the crop from being ruined 

 or nearly ruined by the Brown Rot fungus. The trouble hitherto has been that 

 while liquid spraying either with lime-sulphur or Bordeaux mixture would ward off 

 this disease as long as the mixture remained on the fruit, these substances could 

 not be applied near enough to the time of picking to prevent rot attacking the 

 fruit then, because they would stain the fruit so much that it could not be marketed. 



