EXPERIMENT STATION BULLETINS. 261 



II. EXPERIMENT AT THE COLLEGE IN 1905. 



In the spring about 10 bushels of Eural New Yorker Potatoes were 

 procured. These were badly infected by scab (Oospora scabies), and 

 in many cases nearly the entire starch content of the tuber had been 

 exhausted by the parasite. The potatoes were treated with Formalin 

 for 90 minutes and planted. The ground selected was a fiat, low piece 

 of ground where an old plum orchard had been pulled out in the spring 

 and the land was unsuitable for potatoes. The tubers were planted 

 on the 16th of June in rows 3 feet apart and the seed 15 inches apart 

 in the row. Owing to the late planting, the unsuitable soil and the 

 devitalized condition of the seed the plants were nearly two weeks 

 in appearing above the ground and at first only a feeble growth was 

 made and the outlook was very poor for any kind of a crop. 



The field was divided into sections of six rows each. 



Rows 1-G were to be sprayed every four days with Bordeaux mix- 

 ture. 



Kows 7-12 were to be sprayed every 4 days with the milk of lime 

 alone, at the rate of 4 pounds of stone lime to 50 gallons of water. 



Rows 13-18 were to be sprayed every 10 days with Bordeaux mixture. 



Rows 19-21 were to be sprayed every 15 days with Bordaux mixture. 



Rows 25-30 were to be sprayed every 20 days with Bordeaux mixture. 



Rows 31-31 were to be spraved everv 14 davs with Paris green at the 

 rate of 1 pound to 75 gallons of water. 



Rows 35-41 were to be left unsprayed as a check. 



The plan outlined was carried out to the letter. The first spraying 

 on every plot was given on the 22d of July. The Bordeaux mixture 

 used was composed of 4 pounds Copper Sulphate, 4 pounds Lime and 50 

 gallons of water. 



When the tops were thoroughly dead the different plots were dug. 

 The four center rows only of each section were used in computing re- 

 sults in order that there might be no overlapping of spraying material. 

 The tubers on each plot were graded into merchantable and small, and 

 carefully weighed. 



The table below shows the relative time of dying of the tops and dig- 

 ging of the different plots. 



TABLE XO. 1. 



Manner of Treatment. Pronounced dead. Dug. 



Unsprayed Sept. 13 



Sprayed with Bordeaux every 20 days " 26 



Sprayed with Bordeaux every 15 days " 29 



Sprayed with Bordeaux every 10 days " 29 



Sprayed with Bordeaux every 4 days Oct. 4 



Sprayed with Lime every 4 days Sept. 17 



The blight was first noticed on the unsprayed rows about August 10th, 

 and was very conspicuous by the 15th. The 6 rows sprayed with Bor- 

 deaux every 4 days were but very little affected by the blight. 



