\\heat Rust in Australia. 73 



tend to increase the amount of flag, and retard ripening, by affording an 

 excess of nitrogenous food, whereas phosphate of lime tends to induce 

 early maturity, and' thus enables the crop to escape the rust to a certain 

 extent. 



Treatment of Seed. This was thoroughly gone into, since ft is so often 

 stated that the disease is in the seed. No doubt appropriate treatment 

 destroys the spores entangled in the " brush," but inside the seed no 

 mycelium has been traced. A great variety of " steeps " have been used, 

 and I have myself experimented with over twenty, including the hot-water 

 treatment; but they were all of no practical benefit. Last season (1904) 

 two plots of Queen's Jubilee wheat were sown the same day and grown 

 alongside of each other, in one of which the seed was treated with 

 formalin, while the other was untreated. The rust was bad on both plots, 

 and although special attention was given to the matter in the field, I could 

 not say that treatment of the seed with formalin gave any advantage as 

 regards rust. 



Both sulphate of copper and formalin destroy the rust spores on the 

 seed-grains, and Dr. Hollrung, as the result of a series of experi- 

 ments, has recommended the latter as the best for this purpose. But since 

 infection chiefly takes place when the wheat plant is above ground, it is 

 evident that the formalin treatment does not prevent it, and the experience 

 of numerous farmers who have used formalin successfully for the treat- 

 ment of stinking smut (Tilletia tritici\ bears this out. 



The hot-water treatment of the seed is constantly being brought forward 

 as a remedy for rust, but in 1892 the seed for 118 plots, consisting of 

 different varieties of wheat, was treated with hot water at 55 deg. C., and 

 in some cases the rust was just as bad as if no treatment had been given. 



It was adopted as a conclusion at the last Rust-in-Wheat Conference 

 that the treatment of the seed is valueless for rust, and Dr. Cobb 10 

 one of the representatives of New South Wales, went so far as to say: 

 ' ' As for curing rust by treating the seed, the idea is ridiculous. It would 

 be just as reasonable to expect to prevent measles among mankind by 

 soaking babies in some sort of pickle." 



It has not been thought necessary to refer specially to spraying as a 

 means of combating the rust ; for although this method is practicable in an 

 orchard, and has been found successful in treating peach and plum rust, 

 still the mechanical difficulties to be overcome in spraying a wheat-fielH 

 are so great, that it is no longer regarded as of practical importance. 



So far it would seem as if the rust in wheat defied treatment, and the 

 only practical measures' to be recommended for mitigating its effects were 

 to sow early and to select early maturing varieties. In this way it is often 

 possible to escape the rust, or the crop is too far advanced to suffer 

 seriously. But in this, one is at the mercy of the weather, and the only 

 hopeful remedy i's to grow wheats which will be able successfully to 

 resist the rust, even when the weather favours its development. 



The question has been raised as to whether a wheat which resists one 

 kind of rust cam succumb to another in a different country, and this has 

 really been found to be the case. Professor Eriksson sent me ten varieties 

 of Swedish wheats which had been grown in the experimental plots, and 

 found to resist the rust which is prevalent in that part of the world, viz., 

 Golden Rust (Puccinia glumarum). When grown here these rust-resisting 

 Swedish' wheats became rotten with rust, although of a different kind ; and 

 this, along with other experiments, points to the possibility that a wheat may 

 resist a rust such as P. graminis in one country and succumb to it in another. 



Selection and Cross-breeding. - - As the result of numerous experi- 

 ments, and the trial of hundreds of varieties of wheat from all parts 



