No. 1, AtrcusT, 1920] PATHOLOGY 103 



few of the spots. Infection experiments proved the pathogenicity <>f the organism isolal 

 — Pseudomelia* proteamaculans n. sp. is given as the cause <>f the di Group numl ei 



221.1313023.) [See also next preced in ,756.] G. R. Bisby. 



758. Pbtch, T. Rubber diseases. Tropic. Agriculturist 52: 27 34. 1919. The 

 root disease (Porta hypobrunnea) occurs in Ceylon and Java, in limited areas. The i 

 cation of the disease is somewhat difficult but is unmistakable in young trees, where the top 

 root bears external mycelium which forms stout, red strands which sometimes unite in' 

 continuous red sheet. Internally the strands are white. The mycelium turns bro 

 finally black with age. The diseased wood of young trees is somewhat soft and friable and ; 

 meated with red sheets which often follow the annual rings. In older trees the entire m; 

 lium may be black. — The disease spreads largely from decaying stumps and logs of tree- killed 

 by the fungus. It is held somewhat in check by the careful removal of all felled tiers and 

 old stumps including all diseased lateral roots. — White stem blight and top canker are 

 described briefly. — R. G. Wiggans. 



759. Ramsbottom, J. K. Experiments on the control of narcissus eelworm in the field. 

 Jour. Roy. Hortic. Soc. 44: 6S-72. Fig. 18, 19. 1919. — Three series of experiments for the 

 control of Tylenchus devastatrix are reported. Applications of sulphate of potash alone and 

 in combination with sulphate of ammonia, superphosphate and bone meal did not decrease 

 the attacks. The same was true when various chemicals were applied to the soil. Follow ing 

 an affected crop of narcissus, rye, oats, clover, lucerne peas, broad beans, r3 r e grass, onions, 

 wheat, chives, buckwheat, and potatoes were planted, of which only onions became infested. 

 — J. K. Shaw. 



760. Reinking, O. A. Host index of diseases of economic plants in the Philippines. 

 Philippine Agric. 8: 38-54. 1919. — A host index is presented, showing diseases of about one 

 hundred economic plants in the Philippines. The hosts are arranged alphabetically, and 

 under each host are given the organisms (fungi and bacteria) associated with it and the names 

 of the diseases. In addition to known parasitic forms, saprophytic organisms are included. 

 —S. F. Trclease. 



761. Robson, R. Root-knot disease of tomatoes. Jour. Roy. Hortic. Soc. 44: 31 I 7. 

 Fig. 1 4.-17. 1919. — Root-knot of tomatoes (Heterodera radicicola) was controlled by apply- 

 ing 1,000 pounds cyanide of sodium (or of potassium) per acre to the subsoil. The application 

 of 300 pounds of mercuric chloride also controlled the nematode. The cost of treatment in 

 any of the above methods was approximately £50 per acre. No deleterious effect upon the 

 growing crops was noted as a result of applying the above compounds at the rates per acre 

 given. Mercuric chloride applied at the rate of 775 pounds per acre had a decided stunting 

 effect. — H. A. Jones. 



762. Rosexbaum, J., and Charles E. Sando. Correlation between size of the fruit ?.nd 

 the resistance of the tomato skin to puncture and its relation to infection with Macrosporium 

 tomato Cooke. Amer. Jour. Bot. 7: 78-82. 1920. — As tomatoes grow larger, their resistance 

 to infection by Macrosporium tomato greatly increases. This difference in immunity is appar- 

 ently not due to chemical differences between young and old fruit. Infection may be obtained 

 with fruits of all degrees of maturity when the skin is injured or removed previous to infec- 

 tion. Stomata or other natural openings in the skin are absent. As the fruit develops, the 

 cuticle increases markedly in thickness. Authors show that coincident ly with this, the skin 

 of the fruit becomes more resistant to mechanical puncture with a needle. They suggest 

 that ability to resist infection may be due to the ability of the skin to resist puncture by the 

 fungous filament. — E. W. Sinnott. 



763. Rumbold, Caroline. The injection of chemicals into chestnut trees. Amer. Jour. 

 Bot. 7: 1-20. 7 fig. 1920— See Bot. Absts. 5, Entry 964. 



