Grape* 



201 



of the foliage, and the entire plant suffers through lack of food, which 

 tells upon it the following season. Resting spores or winter fruit are 

 formed in abundance in the tissues of all diseased parts of the vine. These, 

 if not removed, germinate the following spring, and set up the infection 

 again. 



On the first indication of the disease, the Vines should be sprayed with 

 half-strength Bordeaux mixture, the spraying being repeated at intervals 

 .as required, until the berries are set. 



Black Rot OP Anthracnose. (Guigiiardia Bidwellii). This disease is 

 the scourge of American viticulturists, and has proved no less in Europe 

 .since its introduction along with American Vines, imported to replace those 

 destroyed by the Phylloxera. The fungus forms various kinds of fruit, one 

 of which was for a long time known as Phoma uvicola, a name which yet 

 crops up in many works on gardening. The point is to remember that this 

 name refers to the disease now said to be due to Guignardia. The general 

 features of the disease are well marked, and cannot be mistaken. The 

 leaves usually first show the disease under the form of irregularly circular 

 spots, w r hich often run into each other. These spots are sharply marked, 

 and soon become brown and dead, and are then covered with minute black 

 points, the Phoma fruit of the fungus. On 

 the tips of the young shoots the spots are 

 usually elongated, pale, and become more or 

 less sunk below the general surface of the 

 shoot. The berries usually suffer severely, 

 the entire bunch becoming shrivelled and 

 mummified, and covered with minute black 

 warts representing the Guignardia fruit of 

 the fungus. These shrivelled berries do not 

 fall, but hang on the vine for a considerable 

 time, unless removed, as they should be, along 

 with diseased shoots. 



Dr. C. L. Shear, an American plant path- 

 ologist, has paid especial attention to this 

 disease, and has found that by spraying with 

 half-strength Bordeaux mixture, commencing 

 when the shoots are 8 in. to 1 ft. in length, the 

 disease can be held in check. Five or six 

 sprayings, at intervals, are generally neces- 

 sary. If the disease is not checked before the 

 fruit is approaching maturity, then neutral 

 copper acetate, 1 Ib. to 50 gall, of water, 

 should be used, as it does not stain the fruit, 

 whereas Bordeaux mixture does at this stage. 



Brown Mildew of the Vine (Sclerotinia fuckeliana). Too frequently 

 in neglected vineries the leaves and bunches of berries are more or less 

 covered with a dense brown or mouse-coloured mould, often called Botrytis 



Fig. 393. Brown Vine Mildew (Sclerotinia 

 fuckeliana) 



1, Summer fruit on portion of a vine leaf 

 (reduced in size). 2, Summer fruit (natural 

 size). 3, Portion of summer fruit (magni- 

 fied 300). 4, Winter fruit springing from a 

 small black sclerotium (natural size). 5, 

 Mode of spore formation in winter fruit 

 (magnified 200). (Journal Royal Horticul- 

 tural Society.) 



