4o6 THE FUNGUS PESTS OF GARDEN PLANTS 



There is also a Peronospora peculiar to the Pea tribe, another 

 on Spinach, one on Clover, one of the most destructive character 

 on Roses, and others on the many diverse plants of our fields 

 and gardens. We do not illustrate any of these, because 

 they all more or less resemble (though undoubtedly they are 

 quite distinct from) the fungus of the Potato plant. The 

 resting-spores are known in several instances, and where known 

 they fairly agree in size, colour, and general habit with each 

 other. 



PEA DISEASE. Although garden Peas often suffer badly from the 

 attacks of a Peronospora, yet the most deadly foe to Peas, especially 

 late Peas, is a fungus of a totally different character. To such an 

 extent does the Pea blight sometimes devastate the later Peas round 

 London in dry summers, that the whole crop is in some gardens 

 completely destroyed. The name of the fungus of the Pea blight is 

 Erysiphe Martii. Its attack is often made suddenly ; the leaves then 

 lose their natural green colour and become yellowish, and densely 



coated with a fine white bloom ; 

 this bloom becomes at length 

 dusted over with innumerable 

 minute black bodies, which 

 look, under a lens, like tiny 

 spider's-eggs in the web. These 

 little black bodies are filled 

 with extremely small transpa- 

 rent bladders, and each blad- 

 FUNGUS OF PEA MILDEW &vc contains from four to eight 



Erysiphe Martu spores or seeds. Our illustra- 



tion shows the Erysiphe en- 

 larged one hundred diameters, with the bladders containing the 

 spores removed from the globular spots and further enlarged. The 

 fungus of the Hop blight is a close ally of this ; its name is Spharo- 

 theca Castagnei. The Grass blight, Erysiphe gramims, is still nearer. 

 Many other species of fungi belonging to the same order attack our 

 fruit trees, vegetables, and garden flowers. It is, however, unneces- 

 sary to illustrate them, as they bear a more or less close resemblance 

 to the fungus of Pea blight. They all arise from an Oidium condi- 

 tion, similar to the Oidium or mildew of the Vine, and it is in this 

 condition alone, as in the case of the Vine, that they can be reached 

 by any preventive. 



