78 MASS. EXPERIMENT STATION BULLETIN 203. 



Bordeaux Mixture and Lead Arsenate. — The Bordeaux as above, but 

 the powdered arsenical added at the rate of 2 pounds to 50 gallons of 

 water. Some of the leaves were burned. There seems little if any bene- 

 fit to be derived by addition of the lead arsenate. 



Pickering's Lime-water Bordeaux. — The clear limewater and copper 

 sulfate solution were mixed in the proportions recommended by Cook in 

 United States Department of Agriculture Bulletin No. 866. Considerable 

 burning was observed, especially after the first application. 



Sidfur Dust. — This remained on the leaves very well. This plot did 

 not seem to grow as well as the others and the plants were "off color." 

 Since the percentage of control was not so high as for some of the others, 

 it is not to be recommended. 



Sanders Dust. — A very finely ground lime-copper sulfate dust mixture 

 prepared by Riches Piver & Co. of New York. Spreads well, adheres well 

 and causes no burning. Both this and the sulfur dust were appUed while 

 the plants were wet with dew or rain. 



Spraying Results by Growers. 

 Three tobacco growers followed our recommendations and sprayed with 

 Bordeaux mixture or commercial substitutes of the same. No careful 

 counts of results were made, but observations showed good control, and 

 confirmed our results on the station plots. 



Conclusions as to Spraying and Dusting. 



Lime-sulfur and sulfur dust do not give sufficient control; Pickering's 

 mixture and the Bordeaux wdth the addition of lead arsenate cause burn- 

 ing; Pyrox gave less control than some of the others and washed from 

 the leaves too easily. There seems to be little choice between freshly 

 prepared Bordeaux mixture, NuRexo and Sanders Dust. The percentage 

 of control is about the same with all, and there is very little injury. The 

 dust can be more quickly and easily applied, and the writers believe that 

 it can be made to more nearly cover the lower surfaces of the leaves. They 

 prefer the dust to the liquid. For those who prefer the liquid the home- 

 made Bordeaux has the advantages of cheapness and better adhesion. 

 NuRexo, as well as other commercial Bordeaux pastes and powders, has 

 the advantage of being already prepared. 



These conclusions are based on one year's experiments, and therefore 

 should not be accepted as absolute. The experiments will be repeated for 

 several years before final conclusions are drawn. 



Aeration and Watering of Beds. 

 As a result of observations and experiments conducted during the season, 

 it is recommended that the watering of the beds be done as seldom as pos- 

 sible, as the splashing of the water drops from plant to plant was found to 

 spread the disease rapidly. Most of the beds are watered too much and 



