us EXPERIMENT STATION. [Jan. 



Potato Spraying Experiments. 



A large field of potatoes on the college farm was used for 

 experiments in spraying the past season. Tiie field was 

 located on the west sloj)e near the farm barn, and included 

 seven acres. The following varieties were planted: Early 

 Harvest, Early ]\Iicliigan, Carmen Number Three, Green 

 Mountain and Delaware. These were planted in rows run- 

 ning lengthwise of the field. The experiment was carefully 

 planned as regards varieties, conditions of the soil, etc., and 

 running parallel to each of the various treated rows were left 

 untreated ones for the purpose of comparison. 



As there was some delay in obtaining the spraying mix- 

 tures, the whole field, including the checked plants, was 

 sprayed once with Paris green for the potato beetle. In sub- 

 sequent sprayings the following mixtures were used: wet 

 Bordeaux containing Paris green, dry Bordeaux, copper 

 phosphate and a mixture termed "' 1 — 2 — 3." The wet 

 Bordeaux was made according to the standard formula 

 (4 — i — 50). The other mixtures were proprietary sub- 

 stances, and were furnished by the Bowker Insecticide Com- 

 pany, which to our personal knowledge has always taken 

 great pains to place on the market only the most reliable 

 fungicides and insecticides. The " 1 — 2 — 3 " contained 

 compounds of copper, arsenic and lime. The dates of the 

 three apj^lications were July 3, 7, and 12, no spraying being 

 done after the latter date, on account of the luxuriant growth 

 of the tops, which prevented access to the field without damage 

 to the crop. The copper phosphate, dry Bordeaux and 

 " 1 — 2 — 3 " are all dust sprays, and were applied early in 

 the morning with a dust sprayer, when dew covered the 

 foliage. The effects of spraying on this crop were carefully 

 observed by various members of the station staff, together 

 with Mr, Forristall, who supervised all the work, and made 

 most careful observations as to the effects of the different 

 sprays. 



At the close of the experiments corresponding rows of the 

 treated and untreated plants were dug, the potatoes carefully 

 weighed by Mr. Forristall, and the results tabulated. The 

 yields given by the various treatments are as follows : — 



