21G Report of the Department of Botany. 



the value of the results. In this experiment the quantity of potatoes 

 was slightly above ten pounds per cubic foot. The experiment 

 made by Jones and Morse 45 at the Vermont Station in 1905 gave 

 more decisive results, but in this experiment the quantity of potatoes 

 was somewhat less than 3.7 lbs. per cubic foot and the quantity of 

 formaldehyde more than twice that of the standard formula. Further 

 evidence that efficiency is not incompatible with safety is furnished 

 by the earlier experiments of Jones and Morse, but these, also, were 

 made with smaller quantities of potatoes and the gas was not 

 generated by the permanganate method. 



If, upon further investigation, it should be found (as we believe 

 it will be) that a moderate amount of lenticel spotting does not 

 injuriously affect germination or growth, the quantity of potatoes 

 may be safely lowered to 5 lbs. per cubic foot (83 bushels per 1000 

 cubic feet). 



As stated on a previous page, uniform results as regards safety 

 and efficiency can be obtained only by varying the quantity of chemicals 

 according to the quantity of potatoes per cubic foot. Further investi- 

 gation is needed to determine definitely the terms of this relation. 

 At present, it can only be said that with the standard formula of 

 3 pints of formaldehyde and 23 ounces of permanganate to 167 

 bushels of potatoes in 1000 cubic feet (10 lbs. per cubic foot) there 

 will be no injury to the tubers and, probably, scab will be fairly well 

 controlled. 46 No other proportions can be confidently recommended. 

 It is probable that doubling or halving the quantity of both chemicals 

 and potatoes will give similar results, but further experiments are 

 necessary to establish this. 



Aside from what is said above concerning the quantity of potatoes 

 per cubic foot of space we approve the directions for treatment 

 given by Morse in Maine Station Bulletins 141, 149 and 174 except, 

 perhaps, in one respect, viz., the advisability of exposing the tubers 

 in ordinary bushel crates. According to our observation the gas 

 does not readily penetrate to the interior of bushel crates. More 

 uniform results would be obtained if the tubers were exposed in 

 slatted bins only a few inches deep and so arranged that the gas 

 can circulate freely above and below them. 



45 Vt. Sta. Rpt. 18:287-291. 



46 This statement in regard to the efficiency of the treatment is based on the results 



of Morse's experiment at Houlton, Me. 



