214 MAINE AGRICULTURAL EXPERIMENT STATION: I9II. 



dehyde solution. On the third plot were used small, inferior 

 potatoes sorted from the same source of supply as one and two 

 and given the same treatment as regards disinfection as in the 

 case of plot two. 



On July 7 only plots one and two were examined. At this 

 time the disease had not made much progress. No diseased 

 plants were found on a half acre of plot 2 but 2 were found 

 on an equal area of plot one. On July 19 a careful record was 

 made of the number of diseased plants o'n one-i'ourth acre of 

 each plot. Calculated in numbers of diseased ]olants per acre 

 this shows : 



Seed tubers untreated, not selected. Diseased plants per acre 24 

 Seed tubers treated (formaldehyde solution), not selected. 

 Diseased plants per acre 4 



Seed tubers treated (formaldehyde solution), small and inferior. 

 Diseased plants per acre 20 



No effort was made to have the plots of the same size in the 

 two different experiments which were located from one-third 

 to one-half of a mile apart. However, when the number of 

 diseased plants found on the two different plots where un- 

 treated tubers were used just as they came from the bin were 

 reduced to numbers per acre the results were found to be iden- 

 tical. Mr. Porter stated that the seed in each case came from 

 the same bin. 



The Good B^yeriment. 



Mr. Good's field consisted of about 50 acres partly of Green 

 Mountains and partly of Irish Cobblers on sod land on the 

 Donahue farm in Ludlow. The exj)eriment was conducted with 

 the CobT^lers. About 50 barrels of this variety were disinfected 

 by soaking in formaldehyde solution and the remainder planted 

 without treatment. The treatment was performed under Mr. 

 Good's supervision as was the seed cutting but on account of 

 the amount of seed used (250 barrels or more) it was impossi- 

 ble to obtain seed cutters who wo'uld reject entirely all unsound 

 seed. However, as will be noted below, even under these con- 

 ditions, over 90 percent of the disease was eliminated by the 

 treatment. 



The field was visited on July 6 but on account of not being 

 able to determine the exact boundary between the treated and 



