Nx 6. DEPARTMENT OF AGRICULTURE. 747 



alone lessens the liability of attack by the bliglit as the Bord'eaux 

 mixture forms a coating of copper over the foliage thus protect- 

 ing it." 



''Late Blight. — This is a fungous disease which is responsible for 

 the potato rot of the present season in New York State. Its ap- 

 pearance is well known and it has attracted far more attention than 

 has the early blight. The widespread famine in Ireland in 1846, was 

 largely due to the fact that the potato crop was destroyed by the late 

 blight. At the present time another famine is threatening in Ire- 

 land and due to the same cause. In our own country while the dis- 

 aster is not so great yet the loss this year has been enormous, and 

 it is a loss which might have been prevented. 



''This disease in an aggravated form is not difficult to recognize 

 as it may be perceived both by its appearance and disagreeable odor 

 which comes at first from the foliage and later from the decayed 

 tubers. 



''The fungus causing the common potato rot is an old offender. It 

 was undoubtedly introduced into Europe with some of the early im- 

 portations of the potato, and has in certain years proA^ed so destruc- 

 tive that famines have resulted from the entire loss of the potato 

 crop. Such occurences eventually lead to thorough study of the 

 organism. As early as 1846, the fungus causing the trouble was very 

 carefully described in an English publication, and since that time 

 other observers have given the disease much attention. It has 

 spread to many regions in which potatoes are extensively grown, 

 so that both scientists and farmers are very familiar with many of 

 its characteristics. 



"The most interesting feature connected with the fungus is un- 

 doubtedly the wonderful energy which it exhibits, under favorable 

 condntions. in the destruction ol the potato plants. It sometimes 

 spreads with such rapidity that a crop may be ruined in one or two 

 days; and unfavorable conditions, or the total destruction of the 

 plants, formerly appeared to be the only effectual agents in prevent- 

 ing or checking the spread of the dreaded disease. This rapid de- 

 cay of both the foliage and tubers is perhap's the most distinctive 

 of these characters wiiich are commonly brought forward for the 

 identification of the disease. It is almost invariably accompanied 

 by a strong, disagreeable odor which is easily recognized by all who 

 have once experienced it. TSTien large fields have been attacked, 

 the smell is particularly strong; it then arises entirely from the 

 foliage, and is not produced by the tubers. 



"The conditions which favor such rapid decay are, as a rule, not 

 generally present throughout this State. The fungus makes its 

 most rapid growth in a temperature of about seventy degrees Fah- 

 renheit, when much moisture is present in the atmosphere. Cloudy 



