8 MAINi; AGRICULTURAL EXPERIMFCNT STATION. 1909. 



SECOND \EAR POTATO CROP. 



Treatment 1000 lbs. lime 500 lbs. lime no lime 

 Per cent of scab on crop 90 48 13.6 



FIRST YEAR POTATO CROP. 



Treatment 1000 lbs. lime 500 lbs. lime no lime 

 Per cent of scab on crop 52 37 6 



DISCUSSION OE RESULTS. 



As in the previous year the results were quite uniform as well 

 as clean cut and conclusive on the different plots, there being 

 very little variation in plots receiving the same treatment. 

 Taken together the figures obtained during both seasons seem to 

 point to the following definite conclusions with regard to the 

 development of scab on heavily limed Aroostook potato soils. 



First, that the effect of the lime on the amount of scab is fully 

 as great at the end of three years in grass as at the end of two 

 years. In fact the amount of scab on the plots receiving 1000 

 pounds per acre was 10 per cent greater on the land laid down 

 for three years compared with the results obtained' in 1907 on 

 similar adjoining land laid down for two years. Adjoining plots 

 receiving 2000 pounds of lime per acre, hoAvever, have practi- 

 cally the same results 49 per cent and 52 per cent of scab the 

 first year in potatoes, at the end of two and three years respect- 

 ively after liming. 



Second that, on limed soils, scab is largely increased by plant- 

 ing two successive crops of potatoes. In the present instance 

 where a ton of lime per acre was used the per cent of scab 

 increased from 49 per cent in 1907 to 90 per cent or almost 

 double, in 1908, and where one-half ton of lime was used the 

 per cent of scab increased from 27 per cent the first year to 48 

 per cent the second year on the same ground. 



In this connection it is interesting to note that on the unlimed 

 plots there was only a slight increase in the amount of scab the 

 second year in potatoes, and this fully within the limits of 

 experimental error. However, this should not be accepted as 

 conclusive evidence for it iS a matter of common observation 

 that tlite second crop in succession on infected ground is as a 

 rule more scabby than the first crop. 



