798 
Journal of Agricultural Research v 0 i. xxin. no. io 
Premature ripening or the development of “ white heads” is commonly 
found in take-all and footrot, but in the rosette disease, delayed ripening 
occurs in those plants which partially recover from the disease. 
The take-all and footrot type of trouble occurs in varieties of wheat 
known to resist the rosette disease. 
None of the fungi commonly associated with take-all and similar foot- 
rots have been found associated with the rosette disease. 
The rosette disease is diagnosed with greatest certainty in the spring 
before healthy plants reach the boot stage. 
The rosette disease behaves in many ways similar to the Fiji, Sereh, 
and mosaic diseases of sugar cane and the mosaic disease of com. 
The cause of the disease is unknown. 
Soil disinfection experiments made in the field show that a solution 
of 40 per cent formaldehyde and water (1 to 49) applied to infested soil 
will control the disease. The disease developed in nondisinfected plots 
of the same soil located directly adjacent to the disinfected soil. The 
same seed, Harvest Queen (white-chaffed Red Cross), was used in both 
cases. 
A similar experiment conducted using steam-sterilized soil gave the 
same results. 
The foregoing experiment together with winter temperature records 
proves that winter injury and temperature are not the prime causes for 
the rosette disease. This evidence, together with that obtained from 
fertilizer and fallowing experiments, indicates that nonparasitic soil 
factors probably are not the cause of the disease. 
The results from soil disinfection point most forcibly to an organism 
or perhaps a virus as being the causal factor of the disease. 
There is no indication that insects are the cause of the trouble. This 
view is maintained by a number of prominent entomologists. 
Certain unusual intracellular bodies have been found associated with 
wheat plants showing the very early stages of rosette. 
A number of fungi have been found associated with diseased plants 
during certain stages, but none has been found consistently associated 
with the trouble when it makes its first appearance in the spring. 
It has been proved that the disease is soil-borne. While experiments 
have not shown that the disease is seed-borne, certain field observations 
indicate that it possibly may be. 
The causal agent of the disease is known to persist in summer-fallowed 
soil for at least two years without apparent loss of its disease-producing 
powers. 
The disease is controlled through the use of resistant varieties. 
Only 6 per cent of the 150 varieties and selections used in experi¬ 
ments have shown definite susceptibility. 
Extremely late fall seeding with spring emergence of seedlings practi¬ 
cally controls the disease, but this method of control is not practicable. 
