536 THE SMALL GRAINS 



when these are accidentally eaten in sufficient number, a 

 disease known as ergotism. Abortion in stock may be 

 caused if much of it is eaten. 



577. Blade blight of oats. For twenty-five or thirty 

 years, there has been observed a leaf blight of oats in the 

 Eastern area of the United States showing to some extent 

 every year, but apparently more prevalent during a wet 

 spring. There is a discoloration of the leaves, ranging 

 from yellow, through red to brown, but no disturbance in 

 the tissue to indicate the presence of any ordinary fungus. 

 The only critical study of this blight, until very recent 

 years, was made by Galloway and Southworth. In this 

 study 200 cultures were made, in a dozen different 

 media, and two bacteria were isolated, one of them 

 being very abundant. The disease was produced, in 50 

 or more cases, by inoculation with the more abundant 

 organism. After a long period of time, Manns (1909) 

 reopened the subject, called the disease blade blight 

 of oats, and attributed it to two species of bacteria. 

 Experiments showed that aphides are means of carry- 

 ing the disease. The chief weather conditions favorable 

 to the blight are rains, excessive humidity, and cloudi- 

 ness. The greatest loss to oats from the blade blight 

 is a lowered vitality caused by injury to the blades and 

 their final collapse. There is also a smaller loss resulting 

 from direct blasting of the panicles due to the contact 

 with them of sheath lesions. This occurs when the pan- 

 icle is emerging. A similar bacterial disease is said to oc- 

 cur on barley. 



578. Take-all or foot disease (Ophiobolus graminis, 

 Sacc.). This disease is not yet known to be prevalent 

 in this country, but has recently been observed, and may 

 soon become a serious trouble. It has been quite injurious 



