84 St'nikiiig Smut or Bunt in Wheat. 



a little, but not in sufficient quantity to injure the sale of the wheat. It is 

 generally stated that it is the heat of the sun in summer which kills the bunt 

 spores on self-sown wheat, but Farrer' showed that the rains and the dews 

 may also cause the spores to germinate, and having no germinating wheat 

 plants to penetrate, they soon perish. The heat of the sun and the dews at 

 night are likely to prevent the appearance of bunt in a self-sown crop, but if 

 the interval between the harvesting of the crop and the sowing of the next, 

 as well as between the ploughing of the land and the seeding is short, together 

 with cool and dry weather, there may be some danger of infection. In the 

 early days, many farmers used to expose on a cloth the wheat intended 

 for next year's seed. They found that the weather — dews, sunlight, and hot 

 dry winds — acting on the seed for a period of several weeks, killed the spores, 

 or rather, they discovered that it gave a comparatively clean crop, without 

 knowing the reason w^hy. 



7. Why is there more hunt from the same seed in one paddoch than another ? 

 There may be various reasons for this. The land may be fallowed in the 



one case and not in the other. It may also be more moist in one paddock 

 than another, and thus favour the germination of the spores at seeding time. 

 Actually wet soil would be inimical to germination. Whatever delays the 

 first growth of the wheat plant will be favorable to the increase of bunt. 



8. Does the date of seeding influence the amount of bunt in the crop ? 

 Different conditions at seeding time are hkely to affect the result. Bolley^ 



carried out experiments to test this, sowing the same kind of seed on various 

 dates of April, May, and June. He found that the untreated seed yielded 

 the heaviest growth of smut in the earhest date, viz., April. " It was also 

 observed, in all tests, that the number of smutted heads stayed quite approxi- 

 mately in proportion to the total number of heads, the best crop of wheat pro- 

 ducing the best crop of smut.'' I carried out an experiment with flag smut 

 which shows that the date of sowing has a very decided influence. The seed 

 was purposely sown on 24th April and 16th July, or nearly three months be- 

 tween, on land that had borne a crop badly affected with flag smut the pre- 

 vious season. The first was sown when the ground was dry, but there seems 

 to have been no germination until the rain came, which germinated both the 

 seed and the smut, for there were up to 14 per cent, of diseased plants. The 

 later sown was about a month after the rain, and the ground was in excel- 

 lent order, but the spores had evidently germinated and perished in the in- 

 terval, for there was only about 1 per cent, of crop affected. 



The weather and soil conditions enter so much into the result that a dry 

 or a moist seed bed at the time of sowing, or a spell of warmth, or of frost at 

 the time of germination, is bound to make a difference. 



9. Why are some varieties more liable to hunt than others ? 



As afterwards more fully discussed, this may be due to the fact that the 

 least liable variety germinates so rapidly that the smut plant is unable to 

 reach the growing point of the wheat, and so dies, or there may be some- 

 thing in the tissues of the variety unsuitable to the growth of the fungus, and 

 so the variety is said to have the hereditary or inherent quality of bunt re- 

 sistance. 



10. When all the grains are equally inoculated ivith spores, tvhy are some 

 plants bunted and others not ? 



It is quite a common occurrence for inoculated seed to be sown under 

 similar conditions, and yet a number of the plants escape infection. It is 

 not easy to answer the question, but a few considerations may help in this 

 direction. First of all, the young seedling must be at the right stage of 



