i ?o 



A Cucumber Leaf Disease. 



cleansed, so that the start in spring may be as free from risk of 

 infection as possible. 



The remedy, as far as our present knowledge goes, seems 

 mainly to lie in a method of culture (i) by which the foliage is 

 rendered less soft and rank (specially before the plants come into 

 bearing), (2) by supplying more ventilation, as, speaking generally, 

 a good circulation of air not only hardens the foliage, but lessens 

 the chances of germination of spores and subsequent infection of 

 leaves. 



So far, the area in Great Britain infected by Dendryphium is 

 strictly limited. Leaflet No. 76 shews how the spread of 

 the cucumber leaf-blotch fungus, Cercospora, was discovered, 

 in one instance at least, to be due to empty packing cases. Cer- 

 cospora is now doing wholesale damage all over England. 

 Knowing therefore the ease and rapidity with which such fungus 

 diseases spread, it behoves growers to do everything in their 

 power to stamp out any newcomer, such as the subject of this 

 paper. 



Description of Figures. 



Fig. 1. — Cucumber leaf showing pale spots produced by 

 Dendryphium (slightly reduced in size). 



Fig. 2. — Vegetative hyphae of Dendryphium ( x 400). 



Fig. 3. — Section through portion of leaf attacked by the 

 fungus showing conidiophores projecting from lower surface 

 (diagrammatic x 180). 



Fig. 4. — Conidiophores and conidia ( x 400). 



Fig. 5. — Conidia (conidiospores) ( x 400). 



Fig. 6. — Conidia germinating in water alter 24 hours ( x 400). 

 Fig. 7. — Spores of Cercospora showing size as compared with 

 those of Dendryphium ( x 400), 



