FUNGOID DISEASES OF PLANTS 141 



the futility of using the spray after the damage is done. 

 We must be there first, and then the delicate threads or 

 mycelia of the fungal growth cannot find their way into 

 the outer skin of the leaf. The celery seeds themselves 

 may have teleutospores, i.e; resting-spores, upon them, 

 whence it is advisable to steep them in a weak solution 

 of formaUn before sowing, which will kill the fungus 

 but not the seed. Bordeaux may be used for spraying 

 on the field, but as stated, everything depends upon the 

 word " before." (See Plate 32.) 



An alhed Leaf Spot disease also attacks Parsley, and 

 the above remarks will apply in this case also. 



We now pass to Clover Sickness. Here we have a 

 case of what looks Hke one disease arising from two 

 entirely different causes. The clover yellows and withers 

 away in patches, and this is brought about by (1) Eel- 

 worms (see Chapter IV under the head of Strawberry) 

 and (2) the fungus Schlerotina trifolium. (See page 93.) 



A closer examination of the affected plants will show 

 that the eelworm trouble is distinguished by a swelKng 

 of the stalks, whereas in the case of the fungus no such 

 swelling occurs, but dark-coloured excrescences will be 

 found on the roots. (See sketch.) The fungus itself is 

 shown also, cmiously hke so many small megaphones. 

 A spore-bearing myceUum is also indicated, containing 

 eight spores which will presently be released to " carry 

 on " elsewhere. (See Plates 20 and 34.) 



CarboHc emulsion or formahn solution would certainly 

 kill this fungus in the soil, but such treatment is not 

 feasible on a large scale. The Une of action, therefore, 

 is by way of starving the fungus out, in other words keep 

 infected land free from leguminous crops of aU kinds 

 for some years, putting in potatoes or corn instead, and 

 the soil will be freed. 



Wheat and other cereals are often attacked by Puccinia 

 graminis, or Black Rust, to which I have already referred. 

 It begins its curious history as a spore which is released 



