PLAN OF EXPERIMENT. 19 



THE PLAN OK THE EXPERIMENT. 



Ohjeci. — This expetiiiKMit Wiis (U'siuiuhI to dctcruiiiio (1) to wliat 

 extent bitter-rot could be controlled by .sprayin«>- with Bordeaux mix- 

 ture, (2) the tuuiibcr of applications required, and (3) the proper time 

 to make these applications. Owing to the inHuence of weather condi- 

 tions upon this disease it w^as not expected that answers to all these 

 questions could be obtained in a single season; but the season of 1905 

 was so favoral)le to bitter-rot, the disease appearing so early and con- 

 tinnino- with such force throuohout the season, that the results obtained 

 are believed to be a safe guide for almost any season, 



Sjyi'ai/ing scheme. — In order to solve the questions just enumerated 

 it was necessary to cover the entire season with a var3ang number of 

 applications, using a process of elimination in the plan as shown in 

 Table II (p. 23). As may be seen by reference to this table, the dates 

 of the successive applications were as follows: April 8, May 1, May 9, 

 June 12, June 27, July 1»>. July 25, August 7, August 22, and September 

 4. The first date was just after the cluster buds had opened, exposing 

 the blossom buds, ])ut before the latter had opened: the second just 

 after the petals had fallen, and the third apj^lication eight days later. 

 The fourth date was about six weeks after the petals had fallen, the 

 sul)sequent dates being at intervals of about two weeks. The object 

 of the first three applications was to combine the treatment of apple 

 scab with that of bitter-rot and to determine their etiect upon the latter. 

 As shown in Ta])le II, one group of plots (Nos. 1 to 5) receiving three 

 to nine applications had one or more of the late sprayings omitted. 

 From another group (Plots 9 to 12) the early applications for scab Avere 

 omitted. Plots 15, Iti, 17, and 12, receiving four ap\)lications each, were 

 designed to determine the period at which spraying gives the best 

 results. Plots 7 and S combine early and late spraying, leaving an early 

 midseason interval that proved in this case to be too long. Plot 6 was 

 sprayed just before the trees bloomed, as soon as the blossoms were 

 shed, and eight days later (the usual apple-scab treatment), and ever}' 

 two weeks from June 12 to September 4, receiving ten applications in 

 all. It was intended that Plot 9 should be sprayed at intervals qf two 

 weeks, beginning June 12, making the treatment for this plot the same 

 as No. 6, with the three early applications omitted; but the writer inad- 

 vertently overlooked the tirst date. Therefore, in order to avoid dupli- 

 cating No. 10, two more applications were dropped out of No. 9 later 

 in the season. The original scheme included Plots 13 and 14, which 

 were to have received the last three and the last two applications, 

 respectively; but when the time arrived for their treatment to begin 

 the crop on them was already destroyed by the rot and they were 

 therefore dropped. 



Each plot consisted of but two trees. There were, then, in the 

 experimental block fifteen treated plots of two trees each and tive 



