NEMATODE GALLS IN" MARKET WHEAT. 15 



to remain in the water for only as long as absolutely necessary for a 

 thorough removal of the galls or the germination will be affected. 



To summarize, clean seed obtained from outside sources, or seed 

 cleaned by means of floating the galls out of the infected wheat with 

 water, combined with crop rotation, seem to be the most effective 

 methods of controlling this disease at the present time. Experiments 

 in which the Bureau of Markets is cooperating are now being con- 

 ducted by the Bureau of Plant Industry on additional methods for 

 controlling this disease, the results of which will be reported in the 

 future. 1 



The disease propagates easily. This has been brought out several 

 tim^s from the investigations carried on throughout the infected 

 area. One method of propagation is the planting of infected seed 

 wheat. For example, one particular crop which contained these 

 galls was sold for seeding purposes. Without exception the next 

 season every farmer who purchased this seed had an infected crop 

 regardless of the fertile condition of the soil. Farmers who 

 planted their own infected seed harvested each year a greater pro- 

 portion of galls. The highest proportion of galls to sound wheat 

 coming to the attention of the Department of Agriculture was 25 

 per cent. 



Some of the mills which do a seed-cleaning business as a side line 

 return the screenings to the owners to be used for feed. If these 

 screenings contain nematode galls and are given to fowls and stock 

 for feeding purposes they constitute an important means of spread- 

 ing the disease. Feeding experiments 2 indicate that the gall is not 

 digested in all cases, but finds its way into the manure intact. When 

 this manure is spread over the land the land is thus inoculated with 

 these nematode galls, and if wheat is again planted two sources of 

 infection, the seed and manure, are acting to supply infectious ma- 

 terial for the young seedling. It is apparent that such screenings 

 should be burned even at chance of losing some feed. The material 

 removed from infected wheat by floating should also be burned as a 

 precaution against further distribution of this disease. 



Further experiments on this disease from a milling, grading, 

 and distribution standpoint are now being carried forward by the 

 Bureau of Markets in order that a better knowledge of the commer- 

 cial importance of this material as a foreign material in wheat may 

 be obtained. 



1 U. S. Dept. of Agriculture, Office of the Secretary, Circular 114. A Serious eelworm 

 or nematode disease of wheat. 1918. 



2 Marcinowski, K. Parasitica und semiparasitsch an Pnanzen lebende Nematoden. K. 

 Biol. anst. F. land un forstw. Arb. bd., 7 hft. 1, p. 1-192, pi. 1, Berlin, 1909. 



