342 Report of the Horticulturist of the 



Diseases. 



Leaf Spot. — The worst of the diseases which attack the native 

 varieties of gooseberries is a leaf spot which is due to a fungus 

 parasite called Septoria Ribis, Desm. It causes small irregular or 

 circular dead spots to appear in the leaves and weakens them so 

 that they are apt to fall off. By midsummer or later the bushes 

 sometimes lose nearly all their leaves in this way, and whenever 

 this happens the vigor and productive power of such bushes 

 certainly is lessened. 



Pammel, who has treated this disease on black currants, finds* 

 that it may be controlled by five applications of Bordeaux mix- 

 ture, making the first treatment early in May. In treating goose- 

 berries this plan should be changed because the Bordeaux mix- 

 ture would stick to the fruit and show plainly enough to injure 

 its sale. Since the disease is most troublesome in this section of 

 the country after midsummer it seems best to make one spraying 

 before the fruit begins to grow and defer the rest of the treat- 

 ment till the fruit has been picked, but so far as I know, no 

 experiments have been made in treating bearing gooseberry 

 bushes to prevent the leaf spot. 



MildeiD. — This disease seldom troubles the native varieties, but 

 in this country is often destructive to European gooseberries 

 and their American grown seedlings. Its attacks have been so 

 severe as to largely prevent the cultivation of European goose- 

 berries in America in spite of the fact that some of these varie- 

 ties bear fruit of largest size, attractive in color and of excellent 

 quality. The mildew is a fungus which grows on the surface of 

 the green shoots, the foliage and the fruit, injuring the appear- 

 ance of the fruit and stunting the diseased shoots. At first it 

 has a white, frost-like appearance, but later it covers the affected 

 parts with brown, felt-like patches made up of the mildew 

 threads and thick-walled, dark spore cases. Figure 4, plate 

 XIII, illustrates a mildewed branch of the Industry. It is now 

 known that the mildew may be largely prevented by paying 



♦Treatment of Currants to prevent Spot Diseases, Bull. 30, Iowa Expt. Station : 289. 



