The Take-all Disease of Cereals and Grasses 



13 



by lake-all would be determined for each variety. However, in most 

 varieties few disease-free plants were found. Therefore it was impossible 

 to determine accurately the reduction in yield for individual varieties. 

 But the data when averaged for the ten varieties gave fairly accurate 

 figures, and showed that the yield of a take-all-infected plant which is 

 not stunted is reduced 50.2 per cent as compared with that of a healthy 

 plant; that the yield of a plant which is stunted less than half of its normal 

 height is reduced 90.77 per cent; and that the yield of a plant dwarfed 

 to more than half its normal height is reduced 99.39 per cent. The 

 percentage of plants of each variety in each of the above classes, and the 

 average yield in grams of one hundred plants of each variety, are given in 

 table 2. The data in this table show that there is a marked difference in 

 the degree of susceptibility of various wheat varieties. This difference 



TABLE 2. Relative Injury and Yields of Ten Wheat Varieties 



Forward 



Dawson 



Red Wave 



Golden Cross x New Columbia . 



Gold Coin (No. 6 Jr.) 



Currells Prolific x Fultz 



Fulcaster 



Red Rock 



Cosgrove 



P 1008Kanred 



Per cent of plants infected with 

 take-all 



Plants 



less than 



i 



2 



normal 

 height 



11.0 

 21.2 

 11.2 

 23.7 

 22.3 

 38.7 

 23.3 

 39.1 

 32.8 

 47.4 



Average . 



27.07 



Plants 



1 in J 



normal 

 height 



21.1 

 14.4 

 21.5 



22.8 

 28.1 

 18.1 

 22 

 18.9 

 41.4 

 23.0 



23.13 



Plants of 

 normal 

 height 



66.7 

 57.3 

 61.9 

 49.7 

 45.4 

 43.2 

 53.2 

 40.8 

 23.9 

 25.4 



Per cent 

 of plants 



not 

 infected 



1.2 

 7.1 

 5.4 

 3.8 

 4.2 



46.75 



1.5 

 1.2 

 1.9 

 4.2 



Average 

 yield 

 of 100 

 plants 



(grams) 



3.05 



135.4 

 118.0 

 103.6 

 112.9 

 92.3 

 70.4 

 74.78 

 68.50 

 40.40 

 30.00 



84.63 



seems to be constant, since practically every variety held the same relative 

 position of susceptibility in each of the plots. The experiment was 

 repeated in 1923, with duplicated plots. The results substantiated those 

 of 1922 concerning the relative susceptibility of the ten varieties previously 

 used. The testing of additional varieties showed that P 1066, Kanred 

 Ks. 2101, and Turkey, were similar to P 1068 in that they all were very 

 susceptible. Black Winter Emmer showed about the same degree of 

 resistance as Dawson, and Red Winter Speltz and White Beardless Speltz 

 showed greater resistance than any of the other wheats. 



