186 



for from five to seven hours in water at about 62 to 72° F. It is then 

 placed in small bags which can be readily handled, and immersed for one 

 minute in a tub of water heated to 110°-120° F. At the end of the 

 minute it is immersed for ten minutes in a tub of water heated to 129.2° 

 F. and kept at that temperature. The temperature of this tub must not 

 rise above 131° F. At the end of the ten-minute period the wheat is 

 cooled in a tub of cool water and spread out to dry. If the treatment 

 is carefully done, and an accurate thermometer used, there will be no 

 injury to the seed and practically perfect smut-prevention will be obtained. 



Flag Smut 

 Caused by Urocystis tritici Kcke. 



A third smut disease of wheat occurring in Illinois is Hag smut. It 

 attacks the leaves of the wheat plant and appears at first as lead-colored 

 stripes, and those eventually break open, disclosing a mass of smut spores. 

 Diseased plants are usually so deformed that they do not mature. Very 

 rarely does a diseased stalk bear grain. 



Flag smut was first found in Illinois (and in the United States) in 

 1919 in a few fields near Granite City in Madison county. In 1920 it 

 was found scattered over an area of about 2,500 acres in the same region. 

 Since that time, through the search made by the State Department of 

 Agriculture and the Natural History Survey, the disease has been found 

 to occur in the nine counties shown on Map 7. During 1923 it was also 

 found rather wide-spread in Missouri and Kansas. 



In Illinois this disease has been most abundant and most serious in 

 the soft-wheat region in the American Bottoms in Madison and St. Clair 

 counties. Here, in certain wheat fields in 1923, infections involving 

 more than 20 per cent of the stalks were seen. The area of infestation 

 in the seven contiguous counties shown on the map appears to be con- 

 tinuous. At present only a few fields in the southwestern part of Logan 

 county are known to be infested, and in Hancock county just one in- 

 fested field has been found. 



Flag smut is an extremely serious disease. Season by season the 

 limits of its known occurrence are being extended, and the farmers of 

 the state will do well to watch carefully for it in their fields. Once found, 

 every effort should be made to keep it under control. 



As a means of control two procedures are possible, and both should 

 be used. All seed wheat should be thoroughly treated with copper-car- 

 bonate dust before planting. The method used is that described for stink- 

 ing smut (see p. 181). Wherever possible, resistant varieties such as 

 Fulcaster, and the Turkey wheats should be used. 



Scab 



Caused by Gibbcrella saiibinctii (Mont.) Sacc. 



Scab is one of the very serious disea.ses of wheat in Illinois. Like 

 the other diseases which appear in epidemic form, its distribution appears 



