lo Dec, 19 1 :^.] Ri'sulf!< of Sprayit/g for Irish Blight. 745 



RESULTS OF SPRAYING FOR IRISH BLIGHT. 



B\j Geo. Seymour, Potato Expert. 



IMiich difference of opinion exists among potato-growers as lo 

 whether it pays to spray their potato crops. It is well known that in 

 Great Britain and Ireland, where the climate is more humid, and 

 therefore more favorable to the development of late blight, spraying 

 will check the disease, and increase the yield of sound tubers; but the 

 majority of growers in this State argue that, with our dry climate, 

 the disease is not likely to do much harm. This may be true ; but 

 spraying must be done regularly as it is impossible to foretell a visi- 

 tation of the disease. Then again, if spraying is to do the greatest 

 amount of good possible, it is necessary that growers should carry out 

 the work simultaneously. 



In order to gain reliable data, based on local conditions, it was de- 

 cided by this Department to carry out experiments at different centres. 

 For this purpose, plots were established at Crossley and Wollaston. 

 near Warrnambool. for early crops. A plot on the same lines was 

 established at Warragul, on the farm of ]\Ir. S. jNIcKay. for mid-season 

 crop, and at ]Mr. P. H. Ibbott's farm, Pootilla, 2y-2 miles from Bun- 

 garee, for late crop. The scheme embraced five sections in each plot; 

 three of these sections were sprayed from one to three times. In the 

 case of the Warrnambool plot it was deemed advisable to divide the 

 three-spray section, and spray half four times. This fourth spraying 

 evidently had a beneficial effect, as this is the only section that was 

 free of diseased tubers. 



Varieties. 



The varieties planted in the plots were as follow : — 

 New Zealand Pinkeye, at Crossley and Warrnambool. 

 Carman, at Warragul. 

 Snowfiake, at Pootilla. 

 All the fields were carefully inspected before operations were com- 

 menced. Crossley and AVarrnambool were inspected on October 3rd. 

 Previous to this date the weather had been showery, and the soil was 

 in a very moist condition, favorable to the development of the Late 

 Blight, which was found evenly distributed in a mild form over the 

 fields; but the tubers, which were just forming, had not been attacked. 

 In the case of the mid-season plot at Warragul, a similar condition 

 existed. In the late plot at Pootilla. the disease did not make its 

 appearance at any stage. 



The mixture used was copper-soda solution, or Burgundy mixture, 

 of the following strength : — 



12 lbs. sulphate of copper. 

 15 lbs. carbonate of soda. 

 100 gallons of water. 

 This mixture was applied at the rate of 80 to 100 gallons per acre. 

 The latter quantity was found necessary when the plants were large 

 and well grown. The cost of material worked out at about 3s. per acre 

 for bluestone. and Is. per acre for soda; total, 4s. per acre. The cost of 

 15584. 2 1; 



