310 Report of the Assistant Horticulturist of the 
Total No. Per cent, 
of tubers, scabby. 
Irrigated 1,658 48 
Unirrigated 1 , 868 31 
The number of scabby tubers in the product of the irrigated 
portion exceeds the number of scabby tubers in that unirrigated by 
17 per cent, which tends to indicate that excessive moisture favors 
the production of scab. This result coincides with the work of 
Nobbe.* 
Comparing the product of the scabby seed of the irrigated and the 
unirrigated portions with that of the smooth seed of the irrigated and 
unirrigated portions resulted as follows: 
Scabby Seed. 
Whole No. Per cent 
of tubers, scabby. 
Irrigated 823 57 
Unirrigated 961 32 
Smooth Seed. 
Whole No. Per cent, 
of tubers, scabby. 
Irrigated 835 44 
Unirrigated 907 29 
It appears that there were 25 per cent more scabby tubers in the 
irrigated portion planted with scabby seed than in the unirrigated, 
and 15 per cent more scabby tubers in the irrigated portion planted 
with smooth seed than in the unirrigated; or 10 per cent more scabby 
tubers from the scabby than from the smooth seed. 
The difference in the per cent of scabby tubers in the products of 
the smooth and the scabby seed does not appear striking, and does 
not in this case tend to disparage the use of scabby tubers for seed. 
Comparing the manured and unmanured portions, the following 
data are obtained: 
Unmanured. 
Whole No. Per cent 
of tubers, scabby. 
Irrigated 775 22 
Unirrigated 468 21 
* Nobbe found in the water culture of the potato that, from the first 
formation of the tubers grown in water, very small warts were produced by 
excessive local growth of cork. These were not found in the tubers grown 
in the air. Soraur's Handbuch der Pflanzen Krankheiten, p. 84, ed. 1874. 
■ 
