BUREAU OF PLANT INDUSTRY. 171 



A few clays later flag smut, a destructive disease of wheat in Aus- 

 tralia, was discovered in wheat fields in the same county, and in some 

 cases in the same fields as take-all. Pathologists of most of the 

 wheat-producing States, together with a number from the United 

 States Department of Agriculture, were inunediately called together 

 in Illinois in order to become personally familiar with these two dis- 

 eases in tlie field. A survey of wheat fields, not only in Illinois but 

 in many other States, was begim at once so as to determine whether 

 one or both these diseases had become established elsewhere in this 

 country. This survey resulted in the discovery of rather extensive 

 infection in Madison County, 111., with less extensive infection in 

 two other counties in that State and in three counties in Indiana. 



In cooperation with the Federal Horticultural Board and the au- 

 thorities of Illinois and Indiana, action has be^n taken designed to 

 prevent the spread of these two diseases and finally to eradicjite 

 them, if possible. The State officials have established quarantine 

 areas, including the infested fields and the fields which surround 

 them. 



THE NEMATODE OR EELWORM DISEASE OF WHEAT. 



The nematode disease of wheat has been found in Maryland, Vir- 

 ginia, West Virginia, and Georgia and has done considerable local 

 damage. Investigation has shown that the disease attacks rye 

 virulently ; also oats, emmer, and spelt to some extent. Experiments 

 have shown conclusively tliat the nematodes live over winter in the 

 soil. 



A wheat crop may become infected either from the seed or from 

 the soil. To escape infestation, fields should be sown with seed 

 wheat free from mematodes. Such seed wheat may be obtained 

 either from uninfested fields or by treating wheat infested with 

 nematode galls with a 20 to 25 per cent salt solution. In this brine 

 the sound wheat will sink and the nematode galls will float, when 

 they can be removed and destroyed. Experiments show conclusively 

 that sowing seed Avhoat containing nematode galls without such 

 treatment results in a heavily infected crop. Sowing clean seed 

 wheat on infested soil also results in a serious infection of the crop, 

 but clean seed wheat sown on clean land gives a clean crop, even 

 though adjacent to infested fields. 



CONTROL OF CEREAL SMUTS. 



In the fall of 1917 a campaign was started, in cooperation with the 

 extension services of the cereal-growing States, for the prevention of 

 cereal smuts controllable by seed treatment. This work was con- 

 tinued throughout the fiscal year 1919. Demonstrations of methods 

 of seed treatment were held in 28 States, a large number being given 

 in each State. Departmental field assistants addressed groups of 

 farmers and showed them the details of the methods of seed treat- 

 ment. As a result there was a great increase in the quantity of seed 

 grain treated in the last two years. Fully 25 per cent more farmers 

 treated seed for the 1918 crop than for the crop of 1917. The results 

 for the crop of 1919 are not yet compiled, but it is estimated tliat a 

 still larger increase took place in the percentage of seed treated. 



