134 ANNUAL REPORTS OP DEPARTMENT OF AGRICULTURE. 



ROOT-KNOT OF COTTON AND TRUCK CROPS. 



That the root-knot nematode is a larger factor in southern agri- 

 cultural operations than has heretofore been realized is shown by 

 the results of a survey made during the past year by which the actual 

 amount of loss due to this disease in one county in the cotton belt 

 and two counties in the southern trucking district was determined. 

 The average loss per acre from injury to the cotton crop was esti- 

 mated at $3.06. The total loss in this county, which produces on the 

 average 100,000 acres of cotton per annum, was estimated at $280,000 

 for last season. 



In the trucking district, where 2,113 acres of truck crops were 

 examined, the total loss due to root-knot was found to be over 

 $160,700, or an average loss per acre of about $77. Taking these 

 figures as a basis, the total loss in one county was estimated at $390,- 

 000. These results emphasize the economic importance of the root- 

 loiot nematode in the South. The disease is widespread, affecting a 

 great variety of crops and constituting a problem that is finidamental 

 to the agricultural prospects of all southern sandy soils. Satisfactory 

 rotations have been worked out for the cotton belt and are being put 

 into practice. A carefully conducted test to determine the value of 

 cyanogen in the control of the root-knot of dasheens showed that 

 its use is not practicable, as its cost when used in the quantity neces- 

 sary to control the disease is prohibitive. A very successful method 

 of controlling this disease, however, by treatment with hot water has 

 been worked out and thoroughly tested. 



DEMONSTRATIONS OF METHODS FOR THE CONTROL OF COTTON AND TRUCK 



CROP DISEASES. 



Particular attention has been given during the past year to the 

 organization of pathological extension work in the various States, in 

 cooperation with the State extension organizations, in order that the 

 methods of control already worked out for many diseases of cotton, 

 truck, and forage crops might be more clearly demonstrated to the 

 growers and put into actual practice in the infected sections. Plans 

 for the undertaking of such demonstrations in the States of Arkan- 

 sas, Florida, Georgia, New Jersey, South Carolina, Texas, and Ver- 

 mont have been completed and actual demonstrations started on the 

 control of cotton and sweet-potato diseases in some States. Programs 

 of work have been prepared for the wait, root-knot, and anthrac- 

 nose of cotton, for watermelon wilt, anthracnose, and stem-end rot, 

 for asparagus rust, and for sweet-potato diseases. These include 

 provisions for the breeding and propagation of disease-free and dis- 

 ease-resistant seed. Pathological advisers have been appointed for 

 both the northern and southern divisions. These pathologists in- 

 struct the county agents in the details of control methods and assist 

 them in carrying out demonstrations in the infected sections. 



WHEAT BACTERIOSIS. 



A new bacterial disease of wheat has been given very careful study. 

 This disease has been discovered in many States in the Middle West 

 from Texas to Minnesota and Montana, being most prevalent at the 

 present time in Kansas. This disease in favorable years is capable of 



