lo Dec. 191:!.] Ri'snltK of Spraying; for Irish Bliglif. 749 



It has been claimed for spraying that it is beneficial to the crop, 

 apart from checking diseases, because it prolongs the life of the plant. 

 It cannot be said to have had that result in any operations carried out 

 by this Department. It has been noted that the sprayed sections kept 

 green longer than the unsprayed, but it does not necessarily follow, 

 because the leaves are green, that the crop of tubers will show an in- 

 creased yield. The results of plot 4, at Pootilla, are interesting in this 

 connexion, the section sprayed once showed a decrease of 11 cwt. 68 lbs. 

 as compared with the unsprayed section, and the twice spra.yed section 

 a decrease of 14 cwt. H8 lbs. 



In these experiments information has been sought on the following 

 points : — 



1. "What effect has spraying on the disease ? 



2. How many times should the crop be sprayed? 



3. Will spraying increase the yield of the crop? 



4. Does it pay to spray? 



5. What influence has the weather on the disease? 



6. Data in regard to the rainfall during the growing period at 



different centres. 



1. Spraying checks the disease and results in a larger percentage 

 of sound tubers. The increase was in proportion to the number of 

 times the crop was sprayed (see table, plots 1 and 2). 



2. The number of times the crop requires to be sprayed must be 

 determined by the weather conditions during the growing period. 

 Results obtained on plots 1 and 2 in this experiment indicate very little 

 difference between the section sprayed once and the unsprayed section, 

 whilst the section sprayed four times was the only one free from 

 disease. 



3. In these experiments the balance of evidence is that spraying 

 decreases the total yield of the crop, and that the decrease is in propor- 

 tion to the number of times the crop is sprayed. 



4. Judged by the results obtained in these experiments, the answer 

 is No, but owing to the season being unfavorable for the development 

 and spread of the disease, this reply must be considered in conjunction 

 with question No. 1. 



5. A prolonged dry period cheeks the disease in the plants, and is 

 the controlling factor in its attack on the tubers. (See results of 

 plot No. 3, sections 1 and 2). It has been stated that the disease was 

 found in the plants of this plot before spraying commenced ; but no 

 disease was found in the tubers of the unsprayed sections. 



6. Remarkable variations in the rainfall at different centres is re- 

 vealed by table. Plot No. 1 had 44 wet days, with 658 points of rain ; 

 plot No. 2, 33 wet days, with 537 points ; plot No. 3, 34 wet days, with 

 946 points; plot No. 4, 19 wet days, with 537 points, showing difference 

 of 68 per cent, between the highest and lowest records. 



The Water. 



It was evident, in these experiments, that the quality of the water 

 has a great deal to do with the effect of the copper-soda, and Bordeaux 

 mixtures, on the plants. It is recognised that rain-water, or soft river- 

 water, is best for preparing the solution ; that used at Warrnambool 



