4 ALFRED E. CAMERON. 



Plan of the Experiments and Arrangement of Plots. 



The idea was to carry out the experiments on as large a scale as possible, so that 

 the objection which is often advanced, of the futility of forming correct conclusions 

 from the yields of rows treated singly, would not hold good. Therefore at Robbins- 

 ville and Elmer the fields were divided up into plots of 20 rows, and six of these plots^ 

 formed a series. Within the series each alternate plot was a control, treated at 

 Robbinsville with a mixture of zinc arsenite (active ingredient, Zna (As 03)2, not 

 less than 90%) and gypsum calculated to repress the activities of the flea-beetle 

 and Colorado beetle, and at Elmer arsenate of lead (containing not less than 9'8%, 

 total metaUic arsenic, of which not more than 0-48% is water soluble, equivalent to 

 0*75% arsenic oxide) was employed for the same purpose. The other treatments 

 in the block or series varied, viz. : — -at Elmer, Bordeaux mixture combined with 

 arsenate of lead, Kil-Tone, and a mixture of sulphur and lead arsenate ; at Robbinsville, 

 Bordeaux combined with lead arsenate, Yreeland's " Electro " Bordo-Lead, and a 

 mixture of sulphur and zinc arsenite. At Robbinsville, where the field contained 

 sHghtly more than twenty-four acres, this series of plots was repeated four times, so 

 that any inconsistencies due to the nature of the soil might be eliminated as far as 

 possible. At Elmer, where there was approximately ten acres, there was only space 

 for a single repeat. 



The arrangement at Freehold w^as slightly different, the field of about twenty-four 

 acres being divided up into blocks of but eight rows, so that many more control plots 

 could be inserted. Then again every alternate plot was a control, the other plots in 

 the series of six being treated with Bordeaux mixture and lead arsenate, a mixture 

 of sulphur, lead arsenate and gypsum, and Ansbacher's Bordeaux. It will be noted 

 that at each place a different proprietary fungicide was used. 



IVIethods of the Experiments. 



In applying the wet preparations, two types of spraying machines were employed. 

 At Elmer, the Watson Sprayer, made by the Field Force Pump Company of Elmira, 

 New York, gave eminently satisfactory results (fig. 1). 



The only objection that could be advanced was the fluctuation in the maintenance 

 of the pressure from sixty to eighty pounds. It is desirable to aim at getting 

 higher pressure, so that the spray-liquid may be delivered as a fine mist on 

 the leaves. At Freehold and Robbinsville, the power spraying machine made by 

 the Bateman Manufacturing Company of Grenloch, New Jersey, gave the requisite 

 pressure of one hundred pounds, ensuring a uniform application of the fluid (Plate i). 

 In all cases the nozzles were adjusted so that four rows could be covered at one time 

 and were so arranged that they gave the " diamond " effect in their delivery of the 

 spray, a fact of the utmost importance, seeing that it is necessary to cover the 

 under as well as the upper surfaces of the leaves with the fungicide. 



In applying the dust mixtures of sulphur combined with gypsum, arsenite of 

 zinc and arsenate of lead, the Potato Duster (Plate ii), made by the Dust 

 Sprayer Manufacturing Company of Kansas City, Missouri, was used. Here it is 

 necessary to state that the original plan was not carried out in its entirety, and whereas 

 it was intended to apply treatments III and IV (see Table I) as dry powders, so much 



