DISEASES AND PESTS OF PLANTS. 43 



procedure, therefore, there is little that can be done, except to take every cure 

 against injuring the roots in transplanting. It has been suggested that the seed-bed 

 be done away with, and the seed " planted four to a hill and in hills 3 to 4 feet 

 apart in the field." When 5 or 6 inches high the plants are thinned out one to a 

 hill. Whether this would be of practical value under our conditions is doubtful, 

 although on an experimental scale it has been found to much reduce the loss. 



WHEAT. 



STINKING SMUT OR BUNT (Tilletia fcetens and T. tritlci). 



The life-history of this parasite is the same as that of the fungus causing smut 

 of oats, except in certain minute details. The effect on the crop, however, is much 

 more serious. In oat-smut, as a rule, the black spores and the damaged chaff are 

 blown away before harvest, so that, although the yield is reduced, the quality is not 

 impaired. In the case of bunt the fungus does not attack the chaff, but only the 

 interior of the kernel. This becomes filled with a dark-brown, greasy mass of spores 

 which has a very powerful and objectionable odour of putrid fish. Since these 

 affected kernels remain in the ear and are harvested and threshed with the sound 

 grain, they communicate their dark colour and disagreeable odour to the sample of 

 Hour made from such grain. Affected kernels are shorter and broader than normal 

 ones and cause the chaff to stand apart more. They are also lighter and can there- 

 fore be picked out by their broader appearance and more erect habit. As in the 

 case of oat-smut, and for a similar reason, if a plant is attacked at all, usually every 

 ear and each kernel in the ear will be affected. 



Control. The method given under oat-smut is satisfactory, but there is one 

 additional precaution necessary. The affected kernels or " smut-balls," as they are 

 commonly called, may go through harvesting, threshing, and seed-disinfection without 

 being broken. The disinfecting solution cannot penetrate these unbroken kernels 

 sufficiently to kill the contained spores. However, it is quite likely that some of 

 these balls may be broken subsequently in the operations connected with seeding, 

 thus contaminating the seed again with live spores and undoing the effects of the 

 treatment. It is therefore necessary to remove unbroken " smut-balls " before treat- 

 ment, if the sample is found to contain them. Most of them can be taken out with 

 the fanning-mill, but if any are left the grain should be put loose into a barrel or 

 other vessel of water and stirred vigorously. The smut-balls being lighter will rise 

 to the surface and can be skimmed off and burned. They should not be left around 

 or the spores may find their way again into the seed. If this method has to be 

 resorted to, it is better to follow it by immersion in the formalin rather than by 

 sprinkling. 



Bluestone Method. This is satisfactory for wheat, though not for oats. A 

 ^-per-cent. solution is commonly employed i.e., 1 Ib. in 20 gallons and the seed 

 soaked twelve hours. It is then taken out, drained for a few moments, and dipped 

 in lime-water (1 Ib. lime to 8 or 9 gallons of water). This is done to counteract 

 the injurious effect which the prolonged action of bluestone has on the germination 

 of the seed. The seed is then dried and sown. Drills and other implements must 

 also be disinfected. 



LOOSE SMUT (Ustilago tritici). 



This resembles in appearance the loose smut of oats, since it completely destroys 

 the kernels and chaff. By harvest-time nothing is left of the ear except the bare 

 stalk. The life-history of the fungus, however, is quite different. Spoies are blown 

 by the wind into the open flowers of near-by healthy ears. Here they germinate, 

 each spore producing a fungus-thread which enters the developing kernel and gives 

 rise to a rudimentary mycelium. This remains dormant in the germ of the seed 

 until such an infected seed is sown. When the germ becomes active and begins to 

 grow out into the seedling, the mycelium becomes active, too, and behaves from this 



