322 MAINE AGRICULTURAI, EXPERIMENT STATION. I909. 



in some parts of the Province the rot has proven very trouble- 

 some in some seasons" and ''results show that there was less 

 rot on the potatoes on which Bordeaux mixture and Paris 

 Green were used" are not necessarily confusing. They might 

 be made with proj)riety in referring to the late blight of the 

 foliage and the infection and decay of the tuber by the samic 

 fungus resulting from spores being washed down into the soil 

 from the diseased leaves, and in no way be confused with the 

 bacterial trouble. 



To summarize, in no part of the United States has blackleg 

 as yet produced widespread and severe losses to the potato 

 crop. Such losses as have been experienced in Maine are 

 largely confined to the killing of the affected plants before the 

 tubers have reached merchantable size but the amount of this 

 loss appears to be increasing. Little or no loss from decay of 

 mature tubers by this disease has been observed in this state, 

 but much loss from tuber decay in Canada is credited to b. 

 solanisaprus. However, the distribution of the disease 

 is becoming quite general, and it may become a serious pest 

 under certain favorable conditions and in certain sections of 

 the country. In Maine while the losses from diminished crops 

 have not been and may not be great, the real danger is from 

 the possible loss of a valuable seed trade from certain sections 

 where the disease may assume more serious proportions than 

 it does in this state. 



Means oe Prevention. 

 The observations here recorded and the uncompleted bacte- 

 riological studies of the organisms associated with the disease 

 indicate that the introduction of blackleg into uninfected soils 

 can easily be prevented. The organisms are readily killed by 

 exposure to sunlight, even in December when the intensity of 

 the sun's rays is at its lowest ebb. They are also quite 

 susceptible to dessication. Young, active, vigorous cul- 

 tures spread upon small sterile, glass discs, allowed to dry 

 at room temperature were found to be dead in less than half 

 an hour after the moisture had disappeared from the surface 

 of the smear, and thus far no evidence of spore formation has 

 been observed in old cultures. They are, however, able to live 

 a long time in the presence of moisture. 



