EXPERIMENT STATION BULLETINS. 315 



THE BLACK-EOT OF THE GRAPE {Phyllosticta labruscce, Tham.) {Laestadia Bidwellii, (Ell). Via. 



and Eav.) 



In some seasons this disease has played havoc in the vineyards in the 

 southern part of the state, practically ruining the crops. The brown spot 

 disease of the foliage is the same as causes the rot upon the fruit, and, in 

 fact, it generally manifests itself there first. Upon the fruit it shows as 

 small, brown spots, which gradually enlarge until the entire berry has a rot- 

 ten appearance. Up to this time they generally retain their spherical form, 

 but the point first attacked soon begins to shrivel and finally the berry 

 dries away, until it consists of the seeds, covered by the dried pulp and ' 

 skin, the latter in folds and furrows that are always distinctive of the 

 disease. In the meantime small black pimples have appeared upon the 

 berries. These are the perithecia in which the winter spores are 

 developed. 



The fungus also has other reproductive bodies that are developed in great 

 numbers, especially if the weather is warm and moist, and as the same 

 conditions favor the rapid germination and development of the fungus, 

 the injury from the disease is greatly increased when these conditions are 

 present. 



Experiments have demonstrated that in sections where this disease is 

 troublesome it can be held in check by the judicious use of copper com- 

 pounds. If the vines are thoroughly sprayed in the spring before the 

 growth starts, with a strong solution of copper sulphate, and at intervals 

 of two or three weeks, using Bordeaux mixture up to the time the grapes 

 are half grown, and after that a weak solution of copper sulphate or 

 ammoniacal copper carbonate, there will be but little if any loss from this 

 disease, and other fungous diseases will be held in subjection by the same 

 applications. As a rule no application need be made later than the first 

 of August. 



ANTHRAGNOSE (Spaceloma ampelinum, De By). 



This disease is a comparatively new one in this locality and, so far as is 

 known, has appeared in but a few sections in Michigan, and there has done 

 but little harm, as it seems to confine itself to a few varieties, particularly 

 Champion and Vergennes. 



It attacks all new parts of the plants and may appear at any time during 

 the growing season. Upon the leaves, it appears as sunken, brown spots 

 with slightly raised rims. The spots -generally become elongated and the 

 dead tissues take on a white color. It has a similar appearance upon the 

 stems, but it may extend so deep as to practically girdle the branches 

 and cause the loss of both leaves and fruit. The fruit also is very likely 

 to be attacked, the spots at first showing with reddish-brown borders and 

 gray centers. The berries finally wither and dry up until only the skins 

 and seeds remain, but if the spots are small the portion free from disease 

 may keep on growing and, as a result, the berries will crack and expose the 

 seeds. When they wither in this way, they appear quite unlike those 

 attacked by black-rot, since they do not turn brown as in that disease, nor 

 do they take on the wrinkled and pimply appearance so characteristic of 

 black-rot. 



If this disease is allowed to get a start it is generally quite destructive 

 and not only should preventive measures be used, but if it makes its 

 appearance it will generally pay to cut away and burn the infected portions. 



