444 1*HE POTATO. 



Soon the remainder of the leaves become affected and the whole plant 

 eventually wilts and dies. 



At the first appearance if the plants are sprayed several times with 

 Bordeaux mixture its ravages will be prevented. 



A large number of the potato maladies of this country have until re- 

 cently been attributed to this fungus. Late investigations show that 

 there are other diseases that attack the potato, for which the Late Blight 

 has been held responsible. There is however one consoling fact whether 

 we are able to differentiate between this and other troubles or not, and 

 that is, that the remedy for this disease is likewise effective in those for 

 which it may be mistaken. 



!Barly Blight or I^eaf-Spot Disease. This disease which ap- 

 pears early in the summer is caused by the fungi called the macrospor- 

 ium solani. It .shows itself in the shape of small, brown brittle spots 

 which are .scattered over the leaf. If a careful study is made of the leaf 

 it will be found that their upper surfaces are somewhat roughened by 

 darker spots which are raised above the dead tissue which assumes a 

 gray color. These spots are at first small but they slowly increase in 

 size and finally run together and form large brown patches between 

 which is found the leaf becoming yellowish or sickly green in color. 

 The plant finally withers and dies before the tubers are half grown. 

 This fungus is difficult to study in the potato field, because the spores 

 are produced on only a portion of the affected plants. It winters over 

 in the spore stage on the dead vines. Potato vines should always be 

 burned, and if the disease has appeared one year give several early appli- 

 cations of Bordeaux mixture. Do not plant potatoes on the same field 

 the next season. 



Bacterial Blight. There is a potato disease due to bacteria. 

 Since it developes in the tissues that are attacke"d by the fungus just 

 described it is probable that the two have been confounded. There 

 seems to be this difference however, the bacterial blight developes in all 

 parts of the plant, and generally starts from the seed planted which rots 

 in the ground. This disease is most troublesome in warm climates and 

 is shown by the early death of the plants, they oftentimes suddenly 

 wilting and the young potatoes decay. 



Treatment of Diseases of the Potatoes. Experiments show 

 that these diseases may be prevented by spraying with the Bordeaux 

 mixture. Vines thus sprayed remain in a healthy condition long after 



