38 



from which the sporos come, and are carried by the lightest breeze to 

 other berries and to other parts of the vine. 



It does r.ot attack the stalks of the clusters, as in anthracnose ; and 

 on the leaves it is found oiiginating between the veins, not on them, 

 and has minute pimples in a band near the edge of the affected part. 



Grapes are uearly or quite full grown when the disease appears. 

 The spots are first purplish-brown, the whole berry then becomes af- 

 fected and gradually turns black and the pimples make their appear- 

 ance. The grape at the same time shrivels, but does not fall off, and 

 the seeds are clearly seen under the skin which become drawn and 

 ridged. 



Treatment. — Bordeaux mixture should be used, first before the buds 

 open, a second time when the leaves are one-third grown, a third time 

 just before flowering, a fourth time two weeks later. The fifth appli- 

 cation two weeks later should be the ammoniacal copper carbonate solu- 

 tion, and a sixth application of the same may be necessary. If the 

 weather is dry, the number of sprayings m<>y he less. 



Downy Mildew, Brown Rot. 

 (Peronospora viticola, De Bary.) 



Description- — Although this downy mildew, attacks all parts of the 

 vine, the chief mischief is when the leaves are diseased, as then not 

 only the present, but next year's crop is in danger. 



The leaf first turns lighter green where diseased, then yellow, and 

 lastly brown, while if the under surface is examined when the upper 

 has begun to turn yellow, it will be found to be covered with minute 

 threads growing out from the substance of the leaf. 



The grapes are usually attacked before they are half-grown, first 

 turning brown (browu rot), and afterwards grayish (downy mildew). 



Treatment. — If the downy mildew is feared the shoots should be 

 first sprayed with Bordeaux mixture when they are only from six to 

 ten inches long, and afterwards on flowering and at intervals of from 

 2 to 4 weeks. 



Powdery Mildew. 



(Uncinula spiralis, B. & C. 



Desert j tion. — This fungus spreads only on the outside surface of the 

 vine though it sends suckers into the cells immediately below, feeding 

 on their contents and changing the green colour into brown. The 

 fmngus itself is of a grayish white colour, and easily rubs off the leaf, 

 shoot, or grape, when the destruction of the green colour is very no- 

 ticeable. It is generally found on the upper surface of the leaves, 

 which distinguishes it from the Downy Mildew. It develops best dur- 

 ing dry weather. 



Treatment. — As this is only a surface fungus, not penetrating be- 

 yond the outer cells, it is not so dangerous as those previously men- 

 tioned, and the vines do not require treatment for it, until it has ac- 

 tually made its appearance. 



•Sulphur is applied either dry or mixed with water, but this remedy 

 is not considered so valuable as spraying with carbonate of copper dis- 

 solved in ammonia. 



