122 Report of the Botanist of the 



DATES of spraying. 



At Geneva: Series I. — This series, consisting of rows i, 4, 7, 10, 

 and 13, was sprayed three times with bordeaux mixture — July 

 14, 28 and August 26. The first spraying, July 14, was neces- 

 sitated by the appearance of " bugs " in injurious numbers. At 

 this time the plants were about a foot high. To poison the 

 " bugs " white arsenic was used with the bordeaux in the pro- 

 portion of one quart of the stock solution' to 50 gallons of bor- 

 deaux. Three days later there were to be seen only a few " bugs " 

 and no evidence that the arsenic had injured the foliage. 



On July 28 a second brood of " bugs " appeared and it was deemed 

 advisable to poison them. Moreover, the weather was favorable to 

 late blight. Accordingly, a second spraying of the rows in this series 

 was made July 28 with bordeaux and white arsenic mixed in the 

 same proportions as in the previous spraying. Again the " bugs " 

 were killed without any injury to the foliage and there was no further 

 trouble with them during the season. 



The third and last spraying on this series was made August 26 

 with bordeaux alone. Since there were no " bugs " it was unneces- 

 sary to use poison. It appears that this was a time when the rows 

 in this series were much in need of spraying for protection against 

 late blight. They had not been sprayed for four weeks and no 

 bordeaux was to be seen upon them. During the previous three or 

 four days the weather had been wet and " muggy." In some fields 

 northw^est of Geneva there was already considerable blight. It was 

 also abundant in a patch of early potatoes a few rods from the ex- 

 periment and there were even traces of the disease all along the 



^Formula for stock solution of white arsenic: 

 2 lbs. white arsenic. 

 8 lbs. salsoda (washing soda). 

 2 gallons water. 



Boil until dissolved. As a poison, one pound of white arsenic is equal to 

 two pounds of paris green. 



