2i8 Journal of Agricultural Research voi. xv. no. 3 



spraying at frequent intervals throughout the season, the cost would 

 probably be greater than could be compensated by the resulting increase 

 in yield. Cucumber vines normally grow so rapidly that the intervals 

 between spraying would have to be short in order that a considerable 

 portion of the younger leaves would not be exposed to infection a good 

 deal of the time. The fact, however, that the disease is mainly depend- 

 ent on rain for dissemination and that long, rainless periods occur at ir- 

 regular times would make it a hard matter to recommend a spraying 

 schedule which would be economical. 



Spraying where profitable because of other considerations has no 

 doubt been of increased value because of the partial protection afforded 

 from angular-leafspot damage. 



Burger (4) reported beneficial results from spraying for this disease 

 on the basis of a limited amount of spraying in one season. He found a 

 decidedly smaller number of infected fruits in the sprayed than in the 

 unsprayed plots, and reported that the leaves in the sprayed plots were 

 healthier than those in the check rows. It is interesting to note, how- 

 ever, that his recorded yields show that in every case the total yield, 

 including infected and healthy fruits, was greater from the check than 

 from the sprayed plot. This fact may be correlated with the unsettled 

 question of spray injury to cucumber. 



The readiness with which angular-leafspot is spread by spattering of 

 rain makes a spraying experiment, in which the check rows are parallel 

 and adjacent to those sprayed, incomparable to the spraying of a whole 

 field. This fact should be borne in mind when further spraying tests 

 are made. 



SEED TREATMENT 



The evidence indicates strongly that the angular-leafspot organism 

 overwinters principally on the seed. If this be true, the matter of con- 

 trolling the disease is greatly simplified, especially from the standpoint of 

 the industry of growing cucumbers for pickling. Some of the pickle 

 companies grow their own seed, while others buy seed from seedsmen. 

 All companies, so far as is known to the writer, furnish the seed to the 

 growers with whom they contract to raise the cucumbers. There will 

 be little difficulty, therefore, in getting the seed disinfected before it is 

 distributed to the farmers, after a satisfactory method of treatment has 

 been worked out. 



Preliminary tests of treatments with hot water and with chemical dis- 

 infectants have been made. Seed has been treated as follows : Soaked in 

 water at 50° and 52° C. for 10 minutes; in formalin (4 per cent) for 

 5 minutes and 2 minutes; in copper sulphate (i per cent) 10 minutes and 

 5 minutes; and in mercuric chlorid (i : 1,000) for 5 minutes and 2 minutes. 

 These tests were run on such a small scale because of limited greenhouse 

 space for testing germination that conclusions can not be drawn as to 



