2 BULLETIN 734, L\ S. DEPARTMENT OF AGRICULTURE. 



smut, live insects, and odors. The list of foreign material other than 

 dockage now is quite large, and any further addition must be viewed 

 with some concern on the part of the merchant or miller. 



A comparatively new source of foreign material not previously en- 

 countered in marketed wheat has lately come to the attention of the 

 Department of Agriculture; this, if not controlled, will figure con- 

 spicuously both as dockage and foreign material other than dockage 

 in grain. This is a black, misshapen gall resulting from the infection 

 of wheat heads by the nematode Tylenchus tritici (Steinbuch) Bastian. 

 This foreign material, as far as known, has not been recognized by 

 grain inspectors in the commercial grading of wheat. Investiga- 

 tions up to the present time indicate that the disease has a rather 

 limited distribution and there is as yet little evidence to indicate 

 whether it will prove to be a serious factor in wheat growing in other 

 parts of the country. 



On account of the number of places where this disease seems to be 

 established, it was thought necessary to bring the disease to the atten- 

 tion of merchants, millers, and wheat growers in order that they 

 might easily recognize it, have some knowledge of its present dis- 

 tribution, its importance as a factor in affecting market grades and 

 milling quality ; also to give some information concerning its control 

 in order that it may be eliminated efficiently and quickly as a serious 

 pest in wheat. 



PREVIOUS OCCURRENCE OF THE DISEASE. 



This disease has been known as a serious pest in Europe since 

 1745. Has been found in Australia, Austria-Hungary, Ger- 

 many, Holland, Sweden, Switzerland, and very recently in China. 

 Previous citations as to its occurrence in this country are few. 

 Bessey x has noted related forms in various grasses, but did not ob- 

 serve any form attacking wheat. Johnson 2 seems to have first noted 

 its distribution in this country, having found it near Modesto, Cal., 

 in May, 1909. He also reported finding it established in the States 

 of West Virginia, New York, and Georgia, Byars 3 and Fromme 4 

 have reported it from China and Virginia, respectively. 



PRESENT DISTRIBUTION. 



The importance of this disease as a factor in the marketing and 

 milling of wheat first came to the attention of the Bureau of Mar- 

 kets by a request for identification as a troublesome foreign material 



1 Bessey, Ernst, A. A nematode disease of grasses. Science N. S. 21, 391, 1905. 



2 Johnson, Edward C. Notes on a nematode disease in wheat. Science N. S. 30, 576, 

 1909. 



3 Byars, L. P. Tylenchus tritici on wheat. Phytopathology, vol. VII, 56-57, Feb., 1917. 

 * Fromme, F. D. Tylenchus tritici on wheat in Virginia. Phytopathology, vol. VII, 



152-453, Dec, 1917. 



