The Take-all Disease of Cereals and Grasses 33 



Abnormally low temperatures and rainfall in the early spring, such as 

 occurred in 1923, seem to be very unfavorable to the development of the 

 disease. 



McKinney (1922) reports that the most favorable temperature for the 

 fungus to attack wheat seedlings is near 22° to 24° C. This explains why 

 take-all may be more destructive in the earlier-planted winter wheat. 

 After the time of early wheat planting the temperature is often above 

 22° C, but after the time of the late planting the temperature seldom 

 reaches this point. 



Soil fertility and acidity 



Several investigators have studied the relationship between the type of 

 soil and the severity of take-all. Hartmann (1914) and Gray (1914) 

 state that the disease is worse on sandy, light soils than on heavy, stiff, 

 clay soils; while Hori (1901) believes that in Japan the disease is worse 

 on clay or loamy clay than on sandy soils. Richardson (1911) states 

 that take-all occurs on all types of soil. 



Many workers have investigated the influence of various fertilizers and 

 other substances on the development of the disease. Rosen and Elliott 

 (1923) found that under Arkansas conditions commercial fertilizer almost 

 completely prevented the disease while manure decreased the percentage 

 of diseased plants to a considerable degree. Hori (1901), working in 

 Japan, found that the intensity of the damage apparently bears a close 

 relationship to the nature and amount of the fertilizer applied to the 

 soil. The greatest damage occurred when an excessive amount of nitro- 

 genous fertilizer was applied or when the three essential elements were 

 unbalanced. Lime has generally been reported as greatly increasing the 

 amount of disease (Hartmann, 1914, Brittlebank, 1920, and Rosen and 

 Elliott, 1923). Superphosphate of lime has been reported as increasing 

 (Brittlebank, 1920), as not checking (Mangin, 1902), and as decreasing 

 (Anonymous, 1913) the growth of the fungus. Copper sulfate in some 

 cases had no particular effect in the control of the pathogene (Foex, 1919 b), 

 while in other cases it caused a reduction in the amount of the disease 

 (Darnell-Smith, 1916, Foex 1919 b and Benoist and Bailly, 1922). Sul- 

 furic acid and chloride of potassium resulted in a marked reduction in 

 foot rot caused by Ophiobolus cariceti and Leptosphaeria herpotrichoides 

 (Benoist and Bailly, 1922). 



From these more or less conflicting reports there appear to be two 

 factors which decrease the amount of take-all: first, the type of soil 

 fertility which enables the plants to grow at a moderate rale, but not 

 with a profuse vegetative growth such as occurs when an excessive; amount 

 of nitrogen is present; and secondly, an acid condition of the soil. To 

 test the fertility factor in a preliminary way, the following experiment was 

 run in the greenhouse. Twenty-five 5-inch pots were filled with clean 

 soil and were inoculated at the same time and under the same conditions 



