72 TENTH BIENNIAL REPORT 



appearing on the under side as a rust. The spores produced on 

 these, leaves are also yellow or orange in color, which in turn produce 

 another set, brownish in color, which pass to the pine and cause in- 

 fection. (See Fig. 3). Thus the cycle is kept up indefinitely. The 



FlKure 3. Under side of black currant leaf, showing- brown-hair or autumn stage 

 of disease. (Loaned by the courtesy of the Bureau of Plant Industry, U. S. Depart- 

 ment of Agriculture.) 



yellow or summer stage may be noticed on the leaves of wild and 

 cultivated currants and gooseberries from June 1st to the fall of the 

 leaves. The brown-hair or autumn stage (See Fig. 3) may be noticed 

 from about August Ist, often occurring on the same leaves which are 

 still bearing the summer stage. Special attention should be paid 

 to the cultivated black currant, as this is the most susceptible variety. 

 The orange-colored spores ui)on the currants and gooseberries enable 

 it to spread rapidly from bush to bush over a wide area. Some 

 recent evidence by Government pathologists shows that the disease can 

 winter-over on currants and gooseberries as well fis on white pine. 

 It is hazardous, therefore, to ship currant and gooseberry stock at any 



