SPRAYING WITH FUNGICIDES. 41 



cheeked by spraying, there was much conflicting evidence at hand and 

 a great many unanswered questions. Most of the experiments made 

 were conducted for one year only. Many involved only a few trees, 

 and many others were conducted under unfavorable conditions. 



The bitter rot is a disease which has always appeared with varying 

 virulence from year to year, sometimes destroying whole crops, then 

 again attacking only a few apples. It has likewise made its appearance 

 in adjoining orchards atdifferent times in the same year. It is therefore 

 almost impossible to draw any definite conclusions from experiments 

 extending over one year only. Spraying in early summer may in 

 some years check the disease should it appear only a few wrecks after 

 the spraying, while spraying at exactly the same time the next year, 

 when the disease appears late in September, may have absolutely no 

 effect. In order to be of value for a disease dependent upon so many 

 varying factors as is bitter rot all spraying experiments must be con- 

 ducted under exactly the same conditions in the same localities for a 

 series of years without interruptions. Isolated tests may be and doubt- 

 less are of value in indicating what may be expected, but they are at 

 best simply single instances, the results of which can by no means be 

 taken as conclusive. Realizing that such was the case, a comprehen- 

 sive plan for conducting spraying operations was drawn up by Mr. 

 Waite of the Bureau of Plant Industry, U. S. Department of Agri- 

 culture, in the winter of 1900-1901, and this plan was carried out for 

 two years in Virginia, Illinois, and Missouri, one year in cooperation 

 with the Illinois Agricultural Experiment Station/' This plan was 

 stated as follows: The object of this experiment is to answer the fol- 

 lowing questions: (1) Can Bordeaux mixture by proper spraying be 

 made to protect apples from bitter rot? (2) Is winter treatment of 

 the dormant trees of any assistance in the process? (3) Is early 

 spraying more advantageous than late spraying in the treatment of 

 this disease? (4) Are any other fungicides superior to Bordeaux 

 mixture in the treatment of this special malady? To answer these 

 questions the following plan was followed. The parts of the orchards 

 experimented in were laid off in five plats, which were sprayed as 

 follows: 



Flat 1. Winter spraying only. — Spray plat and duplicate with Bor- 

 deaux mixture before the buds swell, applying the spray until the 

 trunk and buds are blue. In duplicates, with controls. 



Plat .'. Combined winter mid spring spraying. — First treatment, 

 winter spraying before buds push; second treatment, when cluster 

 buds are open and flower buds exposed; third treatment, when the 

 last of the petals are falling; fourth treatment, seven to ten days later. 

 In duplicate, with controls. 



«This plan was described in Circular No. 43 of the Illinois Agricultural Experi- 

 ment Station. 



