This is believed to be primarily a gooseberry disease both in Europe and in America. It may, however, cause considerable injury to currant bushes, as was noted in July, 1915, on black currants in a New York State nursery. The disease was then found affecting the varieties Champion, Naples and Saunders, while red currants near by were resistant. The trouble has also been reported from Ohio, Nebraska, Washington and California.

The affected leaves and berries are covered with a brownish felt - like growth.

Although the causal fungus, Sphcerotheca mors-uvce, is morphologically the same as that causing gooseberry mildew, yet limited observations indicate that the pathogene on the currant is so specialized that it refuses to infect even the most susceptible varieties of gooseberries. Conversely, the fungus, even when abundant on gooseberries, is rarely found on currants growing in close proximity. (See Gooseberry, page 222.)

References On American Powdery Mildew

Anonymous. American gooseberry mildew on red currant bushes.

Gard. Chron. 3: 50: 473. 1911. Stewart, V. B. Mildew on black currants. Phytopath. 5:349.1915.

Armillaria Root Rot, Caused By Armillaria Mellea (Fries) Quel

Among the many plants affected by the Armillaria Root Rot is the currant. Severe injury is reported from the Pacific Northwest. Symptoms, cause and control are discussed under Apple, page 96.

Fomes Root Rot Caused by Fomes Ribis (Schum.) Fr.

This is a root disease which has been observed in New York and Minnesota. It probably occurs elsewhere in the United States, since it affects sassafras as well as currants. The fungus Fomes Ribis produces its fruiting bodies around the base of the bush. These are tough, woody, thin, rough, brownish punks, and measure one to two by two to six inches. The diseased roots are abnormally dark, and finally are killed. The destruction of affected plants is advised.

Silver Leap, Caused By Stereum Purpureum Fries

This disease, which is by far the most common on the plum, is sometimes found on the currant. As yet no considerable injury is reported on the latter host. (See Plum, page 368.)