16 BULLETIN 1347, U. S. DEPARTMENT OF AGRICULTURE 
varying degrees of success in controlling the disease. Even when 
successful, however, the expense of these disinfectants in many cases 
is considerable, and under the present conditions these methods are 
not recommended for extensive application in the field. Ferrous 
sulphate has been used with a considerable degree of success in Aus- 
tralia. It is claimed that when this chemical is applied to the soil 
at rates varying between 50 and 75 pounds per acre, the amount of 
take-all is materially reduced. 
Numerous cropping systems and methods of tillage have been pro- 
posed to combat take- all, but it appears that the details of such 
methods must be worked out for the particular climatic conditions 
confronting the grower. The bulk of evidence available indicates 
that summer fallow’ ing and clean cultivation of infested land tend 
to reduce take-all in the following wheat crop. It also is generally 
accepted that oats are a safe crop for rotation on infested soil. Take- 
all is not known to occur on maize or any of the sorghums or legumes, 
and it seems apparent that these are safe rotation crops, in spite of 
the claim of certain European investigators that legumes facilitate 
the growth of the fungus in the soil. Owing to the many grasses 
attacked by Ophiobolus g graminis, take-all can not be eradicated | by 
allowing infested land to lie in pasture. The burning of infested 
stubble “immediately after harvest is recommended widely in Aus- 
traha and is consider ed one of the best means of reducing infestation. 
When this practice is followed the stubble is usually left as long as 
possible or the wheat is not cut at all. The stubble is then rolled ‘and 
burned. 
Late fall sowing has been recommended by several foreign workers 
-as a means of reducing take-all, but owing to the many uncertain 
factors entering into this practice this method should not be recom- 
mended too strongly i in the United States until more is known about 
the influences of environmental factors on infection. 
Several European workers state that heavy seeding tends to in- 
crease the severity of the disease, and they have recommended he¢ht 
seeding on infested soils. However, preliminary experiments carried 
cut in this cor untry have not given results which permit a definite 
statement on this point. 
The use of resistant varieties has been recommended by several 
workers, but as far as can be determined from the literature no va- 
riety of wheat has been found which consistently shows outstanding 
resistance to take-all. Pridham (56) tested a considerable number of 
varieties of wheat under Australian field conditions and found several 
which were not attacked so severely by Ophiobolus graminis as were 
many others. He noted that early short-season varieties were dam- 
aged less by the disease than were the late long-season ones. These 
experiments were carried on for only a year, however, and it is not 
known whether the variations shown among the wheats were largely 
varietal in nature or due in part to other variables. McAlpine (47) 
points out that on some farms Dart’s Imperial wheat is compara- 
tively free from take-all, whereas on other farms this variety is 
severely attacked. The same irregularity is said to occur with the 
variety known as Queen’s Jubilee. Kirby (37), working under 
greenhouse conditions, reports that .the wheat varieties he tested 
showed but sight differences in susceptibility to take-all. Several 
Sedin Fud, eect 
