314 proceedings: botanical society 



The control of the disease in America presents three separate prob- 

 lems: (1) In the territory west of the Mississippi river the disease is 

 not known to occur. During the coming season an extensive survey 

 will be made of these states to determine whether the disease is or is 

 not present. If it has not been carried into this territory on nursery 

 stock, there is little possibility of its getting in by natural means. If 

 the disease should once become established under western forest con- 

 ditions, its control would be hopeless. All 5-needle pines of this area, 

 including the very valuable sugar pine and western white pine, are 

 subject to the disease, and many species of wild Ribes are common. 

 (2) In the states between the Mississippi and the Hudson River, there 

 is an area about 30 miles square in Minnesota and Wisconsin, northeast 

 of St. Paul, which is heavily infected. In Indiana, Ohio, Pennsylvania, 

 and New Jersey the disease has been found in a few nurseries and plan- 

 tations, and is now believed to have been eradicated. In New York 

 it has been found in both nurseries and plantations, and largely eradi- 

 cated. (3) In New England the infection is so general that the only 

 hope of successful growing of white pine in the future lies in the elim- 

 ination of the alternate host of the disease. Whether such elimination 

 can be made at a sufficiently low cost to be profitable has not been 

 determined. Probably in localities where Ribes occur sparsely, as in 

 Connecticut and Rhode Island, a great deal can be accomplished. 



Dr. Metcalf called attention to the larger problem of free trade in 

 plant . diseases and in insect pests. He questioned it as a sound 

 national policy and doubted if the entire importing nursery business is 

 worth as much to the country as the damage which it causes. Not a 

 single plant disease or insect pest that has once become established in 

 this country has been eradicated or is ever likely to be. No matter 

 how well controlled, it remains in every case a permanent tax against 

 our economic resources. To safeguard the country against further 

 invasions is therefore most important. 



Technique for the study of the white pine blister rust: R. H. Colley. 

 (Illustrated with lantern slides.) The study of the blister rust requires 

 a knowledge of the anatomy of the hosts and of the life history and 

 morphology of the fungus itself, since cultural studies are necessarily 

 confined to the host plants. The best available methods of killing, 

 embedding, and sectioning are being employed in working out the re- 

 lation of host and parasite. Flemming's killing solution followed bj r 

 Haidenhain's iron alum-haematoxylin and a counter stain of lichtgrun 

 or orange G have proved very satisfactory for both host and parasite 

 in both the pine and the currant stages. For quick sectioning of 

 doubtful specimens previous to diagnosis the freezing microtome has 

 been very satisfactory. Excellent preparations can be cut, stained, 

 and mounted in two hours. The most satisfactory stains seem to be 

 safranin and lichtgrun. When correctly handled, the hyphae and 

 haustoria of the rust are sufficiently characteristic to be of positive 

 diagnostic value, even before spores are formed. 



