MAINE .STATE COLLEGE 



nature of the disease is established the theories of mechanical 

 and chemical irritation, insect depredations, excess of moisture in 

 the soil, and the attacks of larger fungi must be discarded as 

 primary causes. It is well established by many observers and 

 many experiments, that rubbish, garbage, excess of vegetable 

 matter, fresh stable manure, saw dust, chip manure, ashes and 

 lime, excessive moisture in the soil and growing potatoes from 

 year to year on the same field aggravate the disease. Tt is there- 

 fore certain, that the agents and conditions before regarded as 

 primary causes are secondary, aggravating the disease by pro- 

 ducing conditions favorable to the growth of the parasites. The 

 investigations of Dr. Thaxter indicate that the fungus causing the 

 disease may be a form common in manure and other fermenting 

 organic matter and would be transferred to the soil in such 

 material and reach the potato tubers. Should this prove to be 

 true it would open the question how far diseases affecting farm 

 crops are due to the germs carried to the field in infested fertil- 

 izers and lead to the necessity of adopting means to sterilize fer- 

 tilizers. Certainly it would do but little good to select clean 

 potatoes for seed and plant them in a soil fertilized by material 

 teeming with the organism that causes potato scab. If tLe dis 

 is caused by vegetable parasites, as seems quite probable, then 

 scabby seed and infested fertilizers are the sources of the disease, 

 or the germs may live in the soil over winter. By selecting clean 

 seed and not planting successive seasons on the same ground, two 

 of the sources would be eliminated. This would leave the fertil- 

 izing material as the remaining source of infection. 



It would also be necessary to avoid all general conditions as 

 poorly drained soil, etc., that „ known to favor the develop- 

 ment of fungi. 



Although neither Mr. Bolley nor Dr. Thaxter have sug^ 

 any definite remedies, it is a long stride in the right direction to 

 know the cause of a disease, and as Mr- Bolley says, "The : 

 secuied must of necessity affect the future inv _ ns in the 

 line of prevention ; and the indications are very fav 

 belief that results in that direction may be reached which will 

 have a financial value . • grower.'' Those who wish to 



read the investigations of Mr. Bolley and 1 find 



articles by the former in Agric. Science, Knoxviile. Tenn., 



bt-r and Octol th latter in Conn. Exp t. Sta- 



tion Bub 5, Dec. i- 



Since the above was written Prof. Thaxt - - 3cessful 



