COPPEE SULPHATE (BLUE VITRIOL). 223 



TABLE XXXVI. — Showing Reduction in Germi?iative Capacity by Belay 

 Sowitig after Pickling with Blue Viti-iol. 



Grain. 



Untreated grain 



Treated grain sown Ist day after disinfection 



2nd „ 



3rd „ 



4th „ 

 „ 10th „ 



Loss Per Cent 



in Gei-in:7iative 



Capacity. 



!)5-7.5 



93-5 



910 



86-25 



81-25 



6()-6 



Total 



Germinaiion, 



Per Cent. 



98-6 



97-5 



i 7-25 



95-25 



95-75 



95-75 



Owing to the similarity between the smut diseases of different plants, 

 the methods found efficacious for smut of cereals may be employed in 

 all cases. 



Ustilago Panici-miliacei, Wint. (smut of millet). — The treatment of 

 the grain by Kuhn's method, one hour's steeping in a blue vitriol 

 solution of 0'5 per cent, followed by a 6 per cent milk of lime, pre- 

 vents the infection of the young plant (plantule) by spores adherent 

 to the seed. The same delay in germination was observed by Aderhold, 

 who also found that 86 per cent of the seeds treated germinated, show- 

 ing 04 per cent of rust against 90 per cent of the untr'ated seed with 

 7 45 per cent of rust. It is an excellent palliative, but it is better 

 still to roast the spores by letting them fall through a twig bi oom held 

 1 metre above a very light straw fire. 



Ustilago Maydis, Corda (smut of maize) cannot be avoided as surely 

 as all the other rusts, because the spores of this fungus are of them- 

 selves able to penetrate into the adult plant through the newly formed 

 leaf. In spite of this peculiarity blue vitriol is used with success, but 

 it does not prevent future infecdon of the plant. 



Urocystis Cepida, Frost (smut of the onion). — Although the disease 

 may be suppressed by rejecting all rusty stocks on transplanti g, Mohr 

 points out the good effect of spraying with a 3 per cent solution of blue 

 vitriol. 



Puccinia (rusts). — Three different species are found on grain 

 crops : Puccinia graminis, Pers. (common or linear rust) ; Puccinia 

 Bubigo-vera, Wint. (spotted mildew) ; Puccinia coronata, Cord, (rust 

 of oats). — The development of rust differs totally from the method 

 of propagation of smut and bunt. It is impossible to prevent rust 

 of corn in the same way and at the same timj as smut diseases by 

 simple disinfection of the seed-corn. Their methods of multiplica- 

 tion are so varied that it is, so to speak, impossible to create an obstacle 

 to the propagation of these diseases by chemical means so as to hope 

 for a radical effect, curative or preventive, by the means which render 

 such excellent service in combating other diseases. The means of 

 action are very limited, and direct attack is impossible. It is only 

 from an instructive point of view that the results obtained by spraying 

 with blue vitriol preparations are given. Wuthrich has shown that the 



