330 BROOKLYN BOTANIC GARDEN MEMOIRS 



western white pine, are subject to the disease, and wild Ribes of many 

 species are abundant. No species or variety of Ribes yet tested is 

 immune to the disease. 



Second. From the Mississippi River to the Hudson River. There 

 is an area about 30 miles square in Minnesota and Wisconsin north- 

 west of St. Paul which is now known to be heavily infected. Probably 

 more infection will be found in Minnesota. In Michigan, Indiana, 

 Ohio, Pennsylvania, and New Jersey the disease has been found in a 

 few nurseries and plantations and is believed to have been eradicated 

 at these points. In New York west of the Hudson River it has been 

 found in both nurseries and plantations and largely eradicated, but 

 on account of the extensive planting of pine nursery stock in the 

 Adirondacks heavy infections are to be anticipated there. In general, 

 the commercial currant-growing sections, such as the region from 

 Rochester to Buffalo, may be expected to soon show general infection. 

 In Canada the Niagara Peninsula is already generally infected, and 

 at least scattering infections occur elsewhere in Ontario. This infec- 

 tion is of course a serious menace to Michigan. 



Third. East of the Hudson River. Here infection is so general 

 that the only hope of successful growing of white pine in the future 

 lies in the elimination of the alternate host of the disease; namely, 

 Ribes. Whether such elimination can be made at a suf^ciently low 

 cost to be profitable remains to be seen. Probably in localities where 

 Ribes occur sparsely, as in Connecticut and Rhode Island, a great 

 deal can be accomplished. However, in many sections of rough 

 country, where wild Ribes are too prevalent to be profitably eradicated, 

 white pine growing may be expected to become impracticable. 

 Throughout any section where the blister rust becomes prevalent, the 

 effect is to make the white pine a cultivated plant; that is, it can not 

 be profitably grown, or perhaps not grown at all, unless the ground is 

 kept free from Ribes by artificial means. 



There are certain difficulties which stand in the way of any general 

 campaign of disease control which involves wholesale eradication of 

 diseased and susceptible plants. It remains to be seen whether these 

 difficulties are or are not insurmountable. 



I. There is in the United States no central authority to act in 

 any matter involving destruction of diseased plant material or pre- 

 cautionary destruction of that which is not diseased. Whatever 

 destruction is undertaken must be undertaken in each state under the 

 separate legal authority of that state. The state laws are not uni- 

 form. In some states they are adequate and well supported by public 

 sentiment, in others they are wholly inadequate and apply only to 

 special cases. In general there are few states in which the laws are 



