19 



a solution of sulphate of copper one ounce in two 

 gallons of water. The surrounding soil should also 

 be similarly treated. 



It is very important to remember that this wash 

 should be applied during mid-winter, before the leaf -buds 

 begin to swell in the least, otherwise the foliage will be 

 destroyed. 



ROSE MILDEW (Sphcerotheca pannosa). 



This is undoubtedly the most destructive and, at the 

 same time, the most prevalent disease with which the 

 grower of Roses has to contend. Like most other para- 

 sitic fungi it is sporadic in its appearance ; during certain 

 seasons it assumes the proportions of an epidemic, 

 whereas on other occasions it does but little injury, but 

 it is never entirely absent. The waves of serious disease 

 are mainly due to neglect in not fighting the pest when 

 present in the smallest quantity, which means that it is 

 struggling against difficulties, and could much more 

 easily be overcome. 



The reason why mildew is so much more preva- 

 lent during some seasons than others depends almost 

 entirely on the host-plant, and not on the fungus, which 

 is always present in sufficient quantity to set up an 

 epidemic if conditions are favourable. Broadly speak- 

 ing, " soft " foliage favours the disease, whereas " hard " 

 foliage cannot be so readily infected. This statement is 

 not only true so far as relates to foliage affected by 

 weather conditions, but also as to the relatively hard or 

 soft foliage and shoots of different kinds of Roses. The 

 microscopic structure of the leaf of the " Crimson 



