Dec. 1895.1 



INJUKIOUS INSECTS AND FUNGI. 



323 



putridity, and quickly shrivels up. At this time the fungus 

 produces quantities of seeds, or spores, which are dispersed to 

 begin a new cycle of destruction. 



Mr. Worthington Smith states that the mycelium always 

 attacks the lowest part of the ear first and that he has never 

 noticed the upper part of the ear diseased while the lower part 

 was sound. On the other hand, it sometimes happens that the 

 upper part of an ear is not infected, although the lower part is 

 attacked. 



Oat plants are smutted by a kindred fungus described as 

 Ustilago avence, Persoon ; and barley plants by another styled 

 Ustilago hordei, Persoon. The life history and action of these 

 fungi are similar to those of Ustilago tritici. The oat is more 

 liable to smut than wheat, because the seed has a rough, some- 

 what loose husk, with breaks at the extremity whence the 

 stamen arises in which the spores of the fungus are readily 

 retained and sheltered. Barley is also more frequently smutted 

 than wheat, as the grain has a thick tegument with folds in 

 which spores may easily rest. Jensen states that there are two 

 distinct varieties of Ustilago which attack barley. He defines 

 them as Ustilago tecta and Ustilago niida. He shows that the 

 spores of these varieties are clearly distinct, and that their action 

 on the ears is slightly difi^erent. 



Methods of Prevention. 



Seed wheat should not be taken from an infected crop. Wheat 

 growers who sow seed of their own growth must be careful to avoid 

 taking seed from fields where smutted ears have been noticed. 

 The spores are so numerous that infection is widely spread in 

 various ways, and it would be better to buy seed wheat than to 

 run risks of perpetuating the disease and spreading it through- 

 out the farm. 



Seed wheat should be "pickled," or dressed, to destroy any 

 spores of fungi that may be upon it. This should always be 

 done as a matter of precaution, and especially where there is 

 any suspicion that there was smut in the crop from which it 

 came. 



Sulphate of copper dressings are those usually adopted, and 

 they are undoubtedly the best and most economical in the long 

 run. Sulphuric acid has been used in America, but the results 

 were not satisfactory. Sulphate of potassium has also been 

 tried in France and America with some degree of success. 



The ordinary mode of dressing seed wheat with sulphate of 

 copper in this country is to make a solution of from IJ to 

 2 lbs. of sulphate of copper dissolved in two or three gallons of 

 water, which is supposed to be sufficient for eight bushels of 

 wheat. This solution is ladled, or sprinkled over, the seed wheat, 

 which is turned several times, so that all the grains may be 

 wetted as far as possible ; and the seed is sown as soon as it 

 is dry. This is a rough and ready, and by no means a satisfac- 



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