748 EXPERIMENT STATION RECORD, 



studies the author concludes that the above species are identical, but that the 

 genus should be Phomopsis, and the name P. vexans n. comb., is given it. 



Oxidases in healthy and in curly dwarf potatoes, H. H. Bunzel ( U. 8. Dept. 

 Agr., Jour. Agr. Research, 2 (1914), No. 5, pp. 3113-404, figs. 2i).— Summarizing 

 his investigations on the oxidase in potatoes, the author states that the oxidase 

 activity of the foliage of normally developed potato plants is greatest in the 

 early stages of development. It falls off with the growth of the plants and 

 rises again when the plant's growth about reaches a standstill. Curly dwarf 

 l>otato plants show a greater oxidase activity than healthy ones of the same 

 age, both in the juice of their tubers and in the juice of their foliage. The 

 oxidative activity of the different parts of the potato plant has been established 

 for 18 different reagents. 



A brief bibliography is given. 



A parasite of tomato (Bol. Min. Agr., Indus, e Com. [Brazil], 2 U913), No. 2, 

 p. 165). — A disease of tomato, noted in April. 1912, in northern Italy, is said 

 to be that due to Cladosporiiim fulvum violaccum (E. S. R., 30, p. 749). 



The plaster cast apple specimen, L. E. Melchers {Phytopathology, 4 (1914), 

 No. 2. pp. 113, 114, fiO- 1)- — The author describes a method for the preparation 

 of diseased materials of apple, pear, quince, and other fruits, in which, it is 

 claimed, the characteristics of the disease are completely retained and the 

 material kept readily available for permanent use. 



Apple powdery mildew and its control in the Pajaro Valley, W. S. Ballard 

 and W. H. VoLCK {U. 8. Dept. Agr. Bui. 120 {1914), PP- 26. pis. 6, figs. 5).— The 

 authors describe the powdery mildew of apples, which is caused by Podosphwra 

 leucotricha and P. oxyacanthce. 



In the Pajaro Valley, California, P. leucotricha is very common, attacking the 

 foliage and current year's twig growth. It often makes such rapid progress 

 during the spring and summer that by the end of the leaf-forming season It is 

 said to be difficult to find normal, healthy leaves on certain unsprayed varieties. 

 The fungus is described at some length and notes are given on the susceptibility 

 of different varieties, after which accounts are given of spraying experiments 

 for its control. 



It is claimed that the apple powdery mildew may be controlled by foliage 

 spraying with what the authors call iron-sulphid mixture (which consists of a 

 solution of iron sulphate and lime-sulphur solution), precipitated sulphur, or 

 sulphur In some other finely divided form. In addition winter pruning of the 

 trees so as to obtain stimulating effects and removing mildewed twigs, together 

 with winter spraying with some spray that has the effect of inducing vigorous 

 foliage growth in the spring, should be employed. 



The Jonathan spot rot, M. T. Cook and G. W. Martin {Phytopathology, 4 

 (1914), No. 2, pp. 102-105).— In a previous paper (E. S. R., 29, p. 847) the 

 authors expressed the belief that the Jonathan spot rot was probably caused by 

 species of Alternaria. Other investigators have claimed that it was a physio- 

 logical trouble, due to gas, etc. The authors give a brief account of further in- 

 vestigations to determine, if possible, the cause of this trouble. 



In 1913 a large number of apples were bagged during the growing season on 

 the supposition that if the disease was due to an Alternaria, protection from in- 

 fection would produce clean apples, while if it was due to physiological causes 

 the apples would develop spots the same as those unprotected. The fruit ma- 

 tured and was examined in November and January. 



It was found that the number of spots on the apples bagged previous to June 

 9 was much less than those bagged after that date. As a whole the bagged 

 apples showed less spots than those which were not bagged. Two forms of 

 spots were found, small nearly black Jonathan spots and rather large light 



