336 THE farmers' handbook. 



Until bunt-resisting varieties have been introduced and are in general 

 cultivation it is advisable, in order to ensure clear crops, to assume that 

 all seed is more or less smutty, and requires to be " pickled." The spores 

 are so minute that it is quite possible for enough to be present on the 

 seed-grain to cause considerable smut in the crop and yet to escape 

 detection. 



Experiments made in Italy have shown that a wheat seed which is 

 severely infected with the spores of Bunt does not necessarily give rise to a 

 plant which will be attacked by the disease. The factor which in this case 

 determines the susceptibility to the parasite is the temperature at the 

 time of sowing and during the days of the early phases of development. 

 The more rapidly the wheat grows the more certainly it escapes from the 

 attack of the parasite, and vice versa. The same seed can produce per 

 cent, of infected ears in the first case, as against 80 per cent, in the second. 

 These observations show that when it is wished to determine the efficacy 

 of a fungicide — a special method for Bunt control — the condition of the soil 

 and weather at the time of sowing and afterwards must be taken into 

 consideration. 



Effect of Formalin upon Germination of Wheat Grains. 



Formalin is sometimes used as a pickle at the rate of 1 lb. to 40 or 45 

 gallons of water, but of late years experience has established in many 

 quarters a decided objection to its use as a Bunt preventive, more 

 particularly under our drier Australian conditions. Some experiments 

 carried out by Dr. Darnell-Smith in conjunction with Mr. W. M. Carne* 

 on the use of formalin as a fungicide demonstrated that the principal 

 objection to the use of this fungicide lies in its inhibiting effect upon 

 germination. When formalin-treated grain is sown damp just after treat- 

 ment, the germination afterwards approaches closely to that of the untreated. 

 If kept for a few days, however, before sowing, the germination is much 

 slower and the total less. The formalin appears to have a hardening effect 

 upon the pericarp, rendering it difficult for the embryonic roots to develop 

 normally. Even when germinating, treated seed does not swell to the size 

 of untreated seed. Furthermore, germination is considerably delayed, and 

 when it does occur, in all cases the first root instead of rupturing the root- 

 sheath, breaks it away as a cap, or else never emerges. The first root, 

 instead of being the strongest, either does not develop or is much less 

 developed than the lateral second or third roots. The sowing of formalin- 

 treated grain in dry soil usually results in very poor germination. 



The Treatment of Seed Wheat for Bunt. 



Complaints are made from time to time of the efficacy of the bluestone treat- 

 ment, but when these are investigated, it is generally found that either the 

 bluestone was impure or the work had been carried out carelessly. To secure 

 good results, good bluestone must be used and the directions carefully followed. 



The bluestone treatment is favoured by the Department after many years 

 of testing with all kinds of specifics, the solution recommended being 1^ lb. 

 bluestone to 10 gallons of water. The wheat is immersed for three minutes 



* The Effect of Formalin on the Germination of Plants : G P. Darnell- Smith and 

 YV. M. Carne. Third Report of the New South Wales Government Bureau of 

 Microbiology, 1912. 



