president’s address. 
11 
characterise our English winter. Possibly there may be places in 
Australia in which the temperature falls sufficiently to render the 
mildew spores capable of germination, but they must be few. On 
the other hand the cluster-cup stage is really unnecessary in that 
country for the perpetuation of the fungus, because, by reason of 
the absence of frost, there will always be more or less graminaceous 
foliage in a suitable condition for the rust stage to occur upon. 
If it be argued that since there are no mildew-spores capable of 
germination produced in Australia, therefore the cluster-cup stage 
can never occur, I would remark that European grown straw is not 
uncommonly used for packing, and that the unpacking of parcels 
is an operation very frequently performed in the gardens of private 
houses. 
Very little is known as to the predisposing causes operating upon 
the Wheat plant which are calculated to favour its attack by the 
parasite. We do know, however, that a crop which is over 
stimulated by too abundant a supply of nitrogenous manure is 
especially liable to the disease. It does not seem to matter whether 
the nitrogen be supplied in the form of natural or artificial manure. 
The result is the same — predisposition of the crop to mildew. 
In England, especially in Norfolk, we have long been familiar 
with the fact that a “gathering crop” — that is to say, one in which 
the Wheat plants are few and far between, and in which each plant 
increases by throwing out numerous lateral stems — is especially 
liable to become mildewed. In Australia the very opposite is the 
case — gathering crops suffer less from rust than others do. 
The Barberry mildew, although the most important Wheat-disease, 
oecomonically is not the only mildew affecting this crop. There is 
another whose cluster-cup stage is passed upon certain Boragin- 
aceous plants (Pucciiiia rubirjo-vera = P. d 'isperaa, Eriks, and ldenn.), 
as well as a third, P. r/lumannn, Schum. Special attention has 
recently been paid to these Wheat mildews by the Swedish botanist 
Eriksson, who has published a series of observations on their life 
history, from which it appears that the whole matter is much more 
complex than we have hitherto supposed. The Barberry mildew, 
as has been already stated, occurs not only on Wheat, but on certain 
