DISEASES OF CROPS 249 



slightly depressed. In advanced stages these spots are covered with a 

 dirty gray or pinkish powder which is the spores of the fungus. This 

 disease is carried in the seed and is the cause of heavy losses. 



Damping Off, Sore Shin, Seeding Rot. — These diseases may be due to 

 any one of several organisms. They attack the young plants at or just 

 below the surface of the ground, causing them to rot off and die. They are 

 sometimes the cause of heavy losses. 



There are a number of other diseases of the cotton. The most satis- 

 factory remedy for most diseases is the selection of seed from healthy 

 plants. Where growers experience much difficulty, they should consult 

 with the authorities at the state agricultural experiment station. 



FLAX 



Wilt (Fusarium lini, Bolley). — This is one of the most severe diseases 

 of the flax. Sometimes the organism causing this disease is so abundant 

 in the soil that it leads to the term " flax sick soil." The new plants affected 

 with this disease wilt and die and fields are very frequently seen in which 

 there are large bare spots due to the ravages of this disease. When the 

 older plants are attacked they wilt and gradually turn yellow and die. 



The grower who has any difficulty with this or other diseases should 

 consult with the state agricultural experiment station. 



REFERENCES 



"Diseases of Tropical Plants." Cooke. 



"Fungous Diseases of Plants. ' ; Duggar. 



"Spraying of Plants." Lodeman. 



"Minnesota Plant Diseases." Freeman. 



"Diseases of Economic Plants." Stevens and Hall. 



Michigan Expt. Station (Technical Bulletin 20). "Control of Root Knot Nematode. ' 



Ohio Expt. Station Bulletin 265. "Cob Rot of Corn." 



Pennsylvania Expt. Station Bulletin 136. " Collar-Blight and Related Forms of Fire 



Washington Expt. Station Bulletin 126. "Bunt or Smut of Wheat." 

 Canadian Dept. of Agriculture Bulletin 229. "Smuts and Rusts." 

 U. S. Dept. of Agriculture Bulletins: 



64. "Potato Wilt and Other Diseases." 



203. "Field Studies of the Crown Gall of Sugar Beets." 



216. "Rust of Grain in United States" (Bureau of Plant Industry). 

 Farmers' Bulletins, TJ. S. Dept. of Agriculture: 



333. "Cotton Wilt." 



507. "The Smuts of Wheat, Oats, Barley and Corn.' 



544. "Potato Tuber Diseases." 



555 "Cotton Anthracnose and Its Control." 



618 "Leaf Spot: A Disease of the Sugar Beet." 



625. " Cotton Wilt and Root Knot." 



648. "Thfi Control of Root KftPt," 



