18 MASS. EXPERIMENT STATION BULLETIN 213. 



sprayer can be secured on the local market for $7 to $10.50, while a suit- 

 able dust blower costs $12.50 to $18.50. The advantage which the Bor- 

 deaux mixture has in cheapness, however, is counterbalanced by the in- 

 creased time and labor involved in its preparation. The copper-lime 

 dust is immediately ready for application when received, and the Pyrox 

 or NuRexo has onlj^ to be dissolved in water. 



Dust V. Liquid Sprays. — The results of the six series of tests detailed 

 above indicate that the percentage of control is about the same for the 

 liquid spray as for the dust. In beds where very frequent watering is 

 necessary, there might be some advantage in the liquid sprays, because 

 when once dried on the leaves they adhere much better than the dust. 

 The dust, however, has the advantage that it comes up and covers the 

 lower side of the leaves better than the liquid. The dust can be applied 

 more quickly, but thorough dusting with a rotary hand duster is very 

 hard work if continued for any length of time. The dust is also irritating 

 to the nose, eyes and throat. Cheapness of materials and machines is in 

 favor of the liquid sprays. Altogether, the choice between liquid and 

 dust seems to be a matter of personal taste. 



Home-made v. Commercial Copper Sprays. ■ — In the control obtained 

 there seems ,to be verj^ little difference between the results secured by the 

 home-made preparation and the commercial sprays such as Pyrox or 

 NuRexo. Home-made Bordeaux has the advantage of cheapness, while 

 the commercial spraj's have the advantage of more rapid preparation for 

 application. If a grower has large beds which require frequent applica- 

 tion, certainly it would be more satisfactory to prepare his own fungi- 

 cide. For small beds the commercial sprays might be more satisfactor3\ 

 Clinton and McCormick (2: 386), after experimenting with Bordeaux 

 mixture and a number of commercial copper spraj's, recommend home- 

 made Bordeaux mixture as being cheaper and more effective than other 

 copper fungicides. They tried dust on onl}^ one bed and had no wildfire 

 there on either the treated or untreated plot. 



Best Time of Day for Application. — Dust should be applied preferably 

 in the early morning when the plants are wet, or after watering. When 

 the copper sulfate and lime in the dust come in contact with water, they 

 unite to form Bordeaux mixture, which dries on the leaf and adheres 

 with at least a part of the tenacity of the liquid Bordeaux. If, however, 

 the dust is applied to the drj' plant and water then applied, even when 

 the Bordeaux is formed it is mostly washed from the leaf before it dries . 

 Liquid sprays should be applied when the plants are dry, because the 

 spray is thus not diluted with water alread}^ on there and because less of 

 it drips from the leaves at that time. 



Absolute V. Partial Elimination of Wildfire. — It will be noted in the 

 tables given above that in almost all of the sprayed and dusted plots a 

 certain amount of wildfire appeared. Only in a few tests has it been 

 possible to eliminate all infection. In the first five series of tests, how- 

 ever, it should be remembered that sprinkling cans full of water teeming 



