36 Robert S. Kirby 



In order to determine further whether acidity of the soil was an influenc- 

 ing factor on the disease, a test plot at Ithaca- was laid out in which certain 

 substances were applied to the soil. There were six series of eleven rod- 

 rows each, which differed from one another only in the substance added. 

 In the first series lime was applied at the rate of 1500 pounds per acre; 

 in the second, sulfuric acid, 300 pounds per acre; in the third, lime, 500 

 pounds per acre; in the fourth, sulfuric acid, 100 pounds per acre; in the 

 fifth, sulfur, 1500 pounds per acre; and in the sixth, sulfuric acid, 50 pounds 

 per acre. The arrangement of the rod-rows in each series for testing each of 

 the above substances was as follows : 



No inoculum No substance added 



Pure culture of Ophiobolus cariceti No substance added 



Pure culture of Ophiobolus cariceti No substance added 



Pure culture of Ophiobolus cariceti No substance added 



Pure culture of Ophiobolus cariceti No substance added 



Pure culture of Ophiobolus cariceti Substance added 



Pure culture of Ophiobolus cariceti Substance added 



Pure culture of Ophiobolus cariceti Substance added 



No inoculum Substance added 



No inoculum Substance added 



No inoculum Substance added 



All rows were planted with No. 6 Junior wheat, and the inoculum and 

 acidifying substances were added on the day of planting. During July, 

 1922, the rows were harvested by digging up the plants and taking the 

 percentage of diseased plants, the degree of stunting, and the yields. 

 These data, summarized in table 4, show that the addition of lime increased 

 the yield of take-all-free plants, but that it increased the percentage of 

 infected and badly stunted plants to such an extent that the rows yielded 

 less than did those that received an application of acid. This was due 

 to the fact that the healthy plants in the rows growing in the very acid 

 soil yielded only half as much as did those in the very alkaline conditions. 



Date of planting 



Hori (1901) states that in Japan there is a close relationship between 

 the time of sowing and the severity of take-all, and cites several cases 

 in which barley sown between October 13 and October 27 was much more 

 heavily damaged than was that sown two or three weeks later. In order 

 to get data on the relation of the date of sowing to the amount of disease, 

 two rows each of No. 6 Junior and Forward wheats were sown in infested 

 soil on September 6 and September 29, 1921. The results which are 

 given in table 5, show that later planting decreases the percentage of 

 disease, but at the same time it decreases also the number of heads per 

 plant. 



