158 FUNGOID PESTS OF CULTIVATED PLANTS. 



The same remedies are recommended as have been applied in the case 

 of the English vine mildew, and doubtless the persistent application of 

 sulphur will bring its reward. 



Grevillea, xv. 98 ; Sacc. Syll. x. 1571. 



BLACK ROT OF GKAPES. 

 Guignardia Bidwellii (Viala), PL XIII. fig. 9. 



Doubtless one of the most destructive of our American vine pests, 

 which manifests itself in variable forms, found its way into Europe in 

 1885 with imported vines. 



Young shoots and leaves are first attacked, under the form of small 

 brownish blotches. A fortnight later the fruit shows symptoms of 

 disease by the appearance of small blackish spots ; afterwards the fruit 

 turns black, shrivels, and becomes hard. At this stage the surface of the 

 patches is seen to be studded with little black points, indicating what are 

 termed the pycnidia form of the disease, or the summer fruits. These 

 receptacles contain innumerable minute bodies, or stylospores, which are 

 produced in the interior, and when mature ooze out through a pore at the 

 apex (7-8 p long). This is the condition which was first known, and was 

 then called Phoma uvicola. The stylospores, after their escape, are 

 carried about by moisture over the surface of healthy Grapes, where they 

 germinate at once, enter the tissues, form a diseased spot, and thus dis- 

 tribute the disease. 



Later on other forms of summer fruit supervene, until the final or 

 highest form of fruit appears on the diseased Grapes lying on the ground 

 during the winter. In this stage the sporidia are produced in cylindrical 

 cells, or asci, and come to maturity in the spring. They are almost 

 elliptical, without division, and colourless (12-17 x 4^-5 yu). 



In the United States spraying with Bordeaux mixture is much relied 

 upon. 



Gard. Chron. January26, 1895, p. 101, fig. 13 ; Mass. PL Dis. p. 105 ; 

 Thilm. Pilz. Wein. p. 156, f. 11 ; Tubeuf, Dis. p. 216. 



VINE SCLEROTINIA. 

 Sclerotinia Fuckeliana (De Bary), PL XIV. fig. 11. 



This vine pest appears also under two or three forms, the earliest 

 being that of a mould, representing the conidia, and not uncommon on 

 other plants as well as the vine. In days when it was regarded as a 

 complete or perfect fungus, it was called Botrytis cinerea, and that name 

 is found to be sometimes convenient now (pp. 71, 72). 



The conidia form appears in tufts of a greyish colour, sometimes in 

 large patches. The stems or threads are stout, erect, dingy-olive, some- 

 what branched in the upper portion, the tip of each branch bearing a 

 somewhat globose tuft or cluster of broadly elliptical conidia (8-9 x 6 yu). 



The mycelium of the mould traversing the tissues of the host becomes 

 compacted into numerous small black sclerotia, which pass a period of 

 rest and afterwards produce again the conidial fruit, or the cup-like form. 



The little fleshy cups, or Sclerotinia, resemble a very miniature wine- 



