FUNGOID DISEASES OF PLANTS 143 



in springtime from the straw on which it has been resting, 

 and this spore will only germinate on a barberry or bramble 

 leaf. Here it takes to itself a new appearance, that of 

 the "cluster-cup," and poses as a different plant, once 

 having claimed a different name, by way of showing 

 what a fungus can do if it tries. As the season advances, 

 these cluster-cups fructify, each producing a chain of 

 new orange-coloured spores. The latter are just as fas- 

 tidious about their chosen Hne of develojfment as their 

 predecessors, for they now abandon their old home on 

 the bramble-bush, and insist upon being promoted as 

 Com Rust, penetrating the blades in thin hnes and pro- 

 ducing orange-coloured spores once more, this time posing 

 as Uredo segetum. Finally, as the season is getting on, 

 and it is just possible that these fancy tricks may be 

 discovered, they think they would hke to go home to 

 roost again, so they put on their dark things and show 

 up as P. graminis once more, in the form of dark lines 

 along the ripe straw, all ready for business in another year. 

 Corn is attacked by several fungi in addition to the 

 foregoing, including Bunt and Smut, which appears hke 

 grains of soot in among the ears ; White-heads or Take- 

 all, where the corn assumes a bleached appearance ; 

 and " bhndness " of Barley and Oats, but there is 

 no space available for these. As regards treatment for 

 corn fungi, most farmers elect to face a certain percentage 

 of loss each year rather than lay out money on expedients 

 which may not save their cost. This is practical wisdom 

 as far as it goes, but wherever a fungus has had a serious 

 effect it would be as well to study the progress of the 

 disease from spore to spore again, and then launch an 

 offensive against it at the most hkely period. In the 

 case of Black Rust, for instance, the time for this, if worth 

 while, would be just when the bramble cluster-cups are 

 about to show up, when Bordeaux on all adjacent host- 

 plants should arrest the thing in time, A long rotation 

 also tends to discourage these fungi. (See Plate 34.) 



