76 Stinking Smut or Bunt in Wheat. 



from a crop also bunt free. Only two experiments were made with formalin. 

 In the one the seed was infected from balls soaked for five minutes in a solution 

 of strength 1 in 109 of water, and in the other the strength was 1 in 207 of 

 water. In the first case the plants were all clean, and in the second 48.-3 

 per cent, were bunty. But since the strength of formalin required to destroy 

 the infective power of the crushed bunt-balls probably killed 73 per cent. 

 of the plants treated, as shown by another experiment, it was evident that 

 such a strong solution could never be used in practice. Several experiments 

 were made with bluestone solution of various strengths, and they all showed 

 a high proportion of bunty plants, ranging from 61 to 90 per cent., even 

 although the balls had sometimes been soaked as long as 45 minutes. To 

 take one experiment in Avhich the strength used and the time taken was 

 reasonable : The seed was infected from balls soaked for five minutes in a 

 solution of 1 lb. bluestone in 4 gallons of water. The result was that 77 per 

 cent, of the plants were bunty. 



In the next series of experiments the treated and untreated bunt-balls 

 were placed in the soil at the time of seeding. Untreated bunt-balls w^ere 

 placed in the bottom of the drill, at 1 inch, | inch, and \ inch respectively 

 from each wheat seed, and on one side of it only. The result was that infection 

 occurred at the various distances, and the nearer the bunt-ball was to the 

 seed the greater the infection. This varied from 4 to 17 per cent., and in 

 one case there was no infection at all. 



Bunt-balls treated with formalin, as in the previous experiments, dried 

 and placed in the bottom of the drill, \ inch from each seed and only on one 

 side of it, produced no infection. When bluestone, however, was used, the 

 bunt-balls being soaked in a solution of 1 lb. to 4 gallons of water for five 

 minutes, then dried and placed in the bottom of drill, it was found that when 

 placed 1 inch from each seed there was 1^ per cent, of bunty plants, and when 

 ^ inch from each seed, a little over 6 per cent. These experiments show 

 that, if unbroken bunt-balls are contained in the seed after treatment, they 

 are liable to be broken subsequently and infect the grain, and even if unbroken 

 may infect adjacent untreated plants if sown with the grain. 



In 1900'^ these experiments were continued, but only one is recorded 

 relating to infection after treatment ; and it is very suggestive as to the 

 protective effect of bluestone solution. Minnesota Blue Stem was the variety 

 chosen. The grain was soaked for five minutes in bluestone solution of a 

 strength of 1 lb. in 4 gallons of water, then dried, and afterwards infected. 

 The result was that 1^ per cent, of the plants were bunty, while grain of the 

 same variety taken from the same bulk, infected without any treatment, 

 yielded 12 per cent, of bunty plants. The coating of bluestone on the seed 

 evidently prevents the germ-tube of the fungus penetrating inside to any 

 great extent. 



In 1901, further experiments were made, and Farrer^ records the results 

 of infections after treating different varieties of wheat with bluestone, and 

 then infecting the grains after drying. Purple Straw, Farmer's Friend, and 

 Allora Spring were tested, the grains of each being soaked for five minutes in 

 a 2 per cent, solution (1 in 50), then dried and infected. The percentage of 

 bunty plants varied for each variety. In Purple Straw there was no infection, 

 in Farmer's Friend nearly 2 per cent., and in Allora Spring nearly 9 per cent. 

 The date of planting for all of them was 10th July, and Allora Spring alone 

 was tried later, planting on 2nd August, and using a slightly stronger solution 

 of bluestone over .3 per cent. (1 in 30). Two different plots yielded as 

 nearly as possible the same percentage of bunted plants, viz., 19.74 and 

 19.77. The results here are rather discordant, and Farrer himself confesses 



