184 THE BOOK OF THE ROSE CHAP. 
extremely well. Better no air at all than a cold 
draught when the sun is hot, I am sure. Sulphur 
upon the hot-water pipes is the well-known remedy, 
and for pot Roses I should use finger and thumb 
with sulphur or sulphur solution. 
Orange Fungus or Red Rust.—This fungus-pest is 
not so well known or so harmful as mildew; but it 
is more difficult to combat, either by preventive or 
remedial measures, for its growth is inside the leaves 
and stems of the Rose, and it is only when the spores 
are ready for dissemination, and scatter with a touch, 
that it bursts the membranes of the Rose plant and 
appears outside. 
The life-history of this fungus, known as Coleo- 
sporium pingue and several other names according 
to its different stages, is much the same as that of 
Rose-mildew. Orange fungus has, too, the resting 
stage of winter in small but visible black spots on 
the fallen leaves, the woven mass of mycelium of 
spring in the leaves or leaf-stalks attacked, and the 
summer spores which proceed from it. 
It can be recognised at once by its colour, which 
in the spring is a purple spot with a concave yellow 
centre on the upper part of the leaf and a convex 
bright orange spot underneath, sometimes red at 
midsummer, changing to simple black spots on the 
leaves, which fall quite early in August. In my 
own garden I see very little of the yellow or orange 
stages, but plenty of the last one. 
A considerable point in favour of this pest is that 
it very rarely makes its presence disagreeably and 
harmfully felt till the first bloom, the ‘‘ season ’”’ of 
exhibitors is over. August is the month of its 
power, and at that time whole rows of Roses of 
