3IO MAINE AGRICULTURAL EXPERIMENT STATION. I907. 



seed was perhaps slightly slower to germinate, due to killing 

 back of the tender sprouts which had started, but soon after 

 the young plants appeared above the surface no difference could 

 be detected in the treated and untreated. The crop was har- 

 vested October 8 and the potatoes grown from the several kinds 

 of treated seed were then carefully sorted. Any tubers which 

 had one or more scab spots were placed with the scabby crop. 

 The results obtained are as follows : 



Yields of smooth and scabby potatoes from seed differently 



treated. 





Lbs. 

 smooth. 



Lbs. 

 scabby. 



Total lbs. 

 per plot. 



per cent 

 scabby . 



Formalin solution : 











Seed scabby, 

 " smooth, 



776 

 820.5 



5 

 6.5 



781 

 827 



O.6 

 8 



Formalin gas : 











Seed scabby, 

 " smooth, 

 Sodium benzoate : 



822.5 

 834 



9-5 

 3-7 



832 

 837-7 



I.I 

 O.4 



Seed scabby, 

 " smooth, 

 Untreated : 



849-5 



855-5 



10.6 

 15 



860.I 

 870.5 



1.2 



i-7 



Seed scabby, 

 " smooth, 



792 

 819 



55-i 

 36.7 



847.I 



855-7 



6-5 

 4-3 



DISCUSSION OF RESULTS. 



The trials of the present year confirm what has already been 

 shown on a smaller scale * that exposure to formaldehyde gas 

 is fully as effective a treatment for potato scab as soaking in 

 formalin solution. Moreover this treatment is much more 

 economical in time and labor when large quantities of seed 

 are to be treated. For example the seed for 25 acres of pota- 

 toes could be treated in the room described by using only 4 

 pounds of potassium permanganate and a little over a gallon 

 of formalin with less than 3 days' delay for the entire amount 

 of seed. 



* Vt. Sta. Rept. 18, p. 287. 



