PLANT DISliASES IN I908. 7 



On the John Watson farm in Houlton a s.eries of alternate 

 half-acre plotst were treated by the application of 1000, 500 and 

 no lime per plot respectively, and stocked with clover and oats 

 in the spring of 1905, an untreated check plot lying between each 

 two limed plots. In 1907 a strip sufficiently wide to allow the 

 planting of 5 rows of potatoes was plowed across the middle of 

 these plots and at right angles to them. At maturity the potato 

 crop on these plots was harvested and carefully sorted for scab, 

 care being taken to avoid as far as possible, any cross infection 

 or mixing of soil in the difTerent plots. The results obtained 

 were as follows : — 



Treatment 1000 lbs. lime 500 lbs. lime no lime 

 Per cent of scab on crop 49 2.y 11 



The above results were so striking that it seemed worth 

 while to continue the experiment for another year by replanting 

 the same and also planting another equal strip, along side, which 

 was in grass last season. Therefore, one series of potato rows 

 running across the lime plots at right angles was on land which 

 since the application of lime had been one year in oats, one year 

 in grass and clover, and one year in potatoes fertilized with 1200 

 pounds of commercial fertilizer per acre and will be designated 

 as the second year potato crop. The other given below as first 

 year potato crop was on land adjoining and parallel to the first, 

 like it in every way as to soil and treatment except that it had 

 been one year in oats and two years in grass and clover since the 

 lime was applied. 



As in 1907, untreated, clean seed tubers were used for plant- 

 ing, and 1,200 pounds of high grade potato fertilizer applied 

 per acre. On' digging, the two rows at the junction of the potato 

 plots were rejected as was the crop on all the rows for about 15 

 feet on either side of the jimction of the limed with the check 

 plots in the original grass land. In sorting, all tubers showing 

 plainly marked scab spots were placed in that class. The follow- 

 ing is a summary of the result obtained. 



t In the previous report the plots were given, through error, as acre 

 plots, thus making the amount of lime per acre one-half what it really 

 vvras. 



