MICHIGAN ACADEMY OF SCIENCE. 115 



Tlu' fact that only one-half of the field was sprayed and the re- 

 mainder usually became seriously affected added greatly to the 

 difficulty of securing the greatest amount of success in the work. 

 The percentages are based on actual count and they should be fairly 

 correct as to the amount of disease present. 



To be effective the fungicide must so cover the cucumber fruits 

 that spores germinating in a drop of water will come in contact 

 with the spray. The spray must be on the plant before the rainy period 

 in order to give complete protection. The cucumber plant grows 

 very rapidly and will produce fruits continually. Hence, to give 

 complete protection, it would be necessary to spray at least, at 

 intervals of two days, a thing which is not practical in commercial 

 growing. 



The next best thing is to make each spraying as efficient as 

 l)ossible. Hence it is not necessary to spray so often dur- 

 ing periods of dry weather, in fact it is better not to spray at 

 .vuch times, since the pollination may be injured to some extent 

 at every spraying. But if the grower can keep in touch with 

 weather predictions and study local conditions, he may be able to 

 get a fair idea of the conditions which may prevail for the next 

 few days and endeavor to forestall the danger periods by applying 

 the spray as sliortl}' before the rain as possible to pennit drying. 



This is theoretically the proper way to apply fungicides but it 

 will recjuire some effort and foresight on the part of the grower to 

 f((ll(»\v out these principles successfully. 



RBCOMMDNDATIONS FOR CONTROL. 



The problem of controlling CJadosporiuni, cuctinicriniiin does not 

 lie in developing an efficient fungicide as the laboratory tests made 

 show that Bordeaux is effective against the spores of this fungus. 

 The difficulty in control lies rather in the rapidity of growth of the 

 cucumber jdant and fruit, coupled with the rapid develojjment and 

 spread of the luiigns which ]ti('\(Mit comjdete protection of the 

 plant. 



The foll()\\ing reconnnendati(»iis. however, can be made: 



1. The general necessity of spraying must be recognized. 



-. All trash and vines should be burned each year and rotation 

 of crops practiced. 



.'1. Vines may be turned over to allow them to dry after heavy 

 dews or showers. This is a common practice with some growers 

 and should prove valuable in times of epidemic. 



