DISEASES OF PLANTS. 749 



in bligbt -infested tubers, entering in this case not only throngh the buds l)ut 

 through those parts of the sliin which had been damaged by the fungus. 



The results of the investigation indicated that the storage and cooking quali- 

 ties of the tubers were not injuriously affected by the treatment. 



Investigations on the root disease of sugar cane, J. It. Johnston {Porto 

 Rico Proy., 3 (1012), No. 10, pp. 11, j?5). — As a result of examinations of canes 

 diseased near the root, the author thinks that there are in Porto Rico various 

 types of root disease, only one of which, Marnsmius sdcchari, has been well 

 worked out. Some other forms found on diseased roots are Clathrus sp., 

 Asterostroma alhidocarneum, and perhaps, Corticium sp., some of which may be 

 important factors in the production of this condition. 



Report of comm^ittee on root gall to the American Association of Nursery- 

 men, E. A. Smith (Xat. Nurseryman, 20 (1912), No. 8, pp. 300, 301) —A pre- 

 liminary report is given of cooperative experiments that have been established 

 by a committee of the American Association of Nurserymen, the work having 

 been undertaken during 1011. The experiments, some of which are in coopera- 

 tion with experiment stations, are now in progress in 10 different States, the 

 object being to determine the cause and method of control of the different forms 

 of root gall on nursery stock. 



Apple blister canker and methods of treatment, W. O. Gloyeb (Ohio Sta. 

 Cire. 125. pp. I.'f9-161, figx. 7). — The author describes the blister canker of 

 apples due to the fungus Nummularia discreta, which is said to be quite preva- 

 lent in southern and eastern portions of Ohio. The fungus is said to be a wound 

 parasite, and is difficult to control when once it has attacked a tree. Except 

 in cases of slight attack the tree ultimately succumbs to the disease. 



To prevent infection from the blister canker fungus the author recommends 

 that precautions be taken to prevent the drying of the tissues following pruning 

 or other injury. This may be dune by covering the wounds with a suitable 

 dressing, such as asphaltum, grafting wax, etc. Proper orchard sanitation, 

 such as removal and destruction of diseased parts, is also recommended. 



Bitter pit in apples, A. J. Ewart (Proa. Roy. Soc. Victoria, n. ser., 2.'t 

 (1911), No. 2, pp. 367-JtW). — The author conducted a series of experiments to 

 test the theory of Miss White (E. S. R., 26, p. 55) that bitter pit of aiTples is due 

 to local poisoning. In his experiments a large number of inorganic, organic, 

 and gaseous poisons were tested on the pulp of apples under varying conditions. 



It was found that the ripe pulp cells of apples are more sensitive to various 

 poisons than any other known organisms, the limit of toxic action in the case of 

 mercuric chlorid being with a concentration of 1 to 10,000,000.000. The cuticle 

 and bloom of sound apples were found remarkably impermeable to poisons, but 

 when these were removed the poison penetrated readily. Yoimg apples were 

 found more easily penetrated by dissolved poisons than old ones, but their pulp 

 cells were more resistant. Hence a young apple may absorb sufficient poison to 

 kill a portion of its tissue when more mature, without any immediate toxic 

 effect being shown. 



Substances occurring normally in the soil, it is stated, may exercise a toxic 

 effect on the fruit when presented singly, but in mixtures their individual 

 poisonous action is decreased. The poisonous action of copper sulphate and 

 other soluble metallic substances may be decreased by the addition of sub- 

 stances which decrease the percentage of free ions, and in this way it is possible 

 to modify Bordeaux mixture and arsenate of lead without appreciably affect- 

 ing their value as insecticides and fungicides. Zinc arsenite was found less 

 poisonous than lead ar.senate and is considered equally effective as an insect 

 poison. Among the gases present in the air, ozone, ammonia, and nitric acid 

 were found able to produce surface pitting in apples, but only in amounts and 



